Network Working Group J. Preuß Mattsson Internet-Draft G. Selander Updates: 6698 (if approved) Ericsson AB Intended status: Standards Track S. Raza Expires: 12 November 2026 University of Glasgow J. Höglund RISE AB M. Furuhed IN Groupe L. Liao NIO 11 May 2026 CBOR Encoded X.509 Certificates (C509 Certificates) draft-ietf-cose-cbor-encoded-cert-19 Abstract This document specifies a CBOR encoding of X.509 certificates. The resulting certificates are called C509 certificates. The CBOR encoding supports a large subset of RFC 5280 and common certificate profiles, and it is extensible. Two types of C509 certificates are defined. One type is an invertible CBOR re-encoding of DER-encoded X.509 certificates with the signature field copied from the DER encoding. The other type is identical except that the signature is computed over the CBOR encoding instead of the DER encoding, thereby avoiding the use of ASN.1. Both types of certificates have the same semantics as X.509 while providing comparable size reduction. This document also specifies CBOR-encoded data structures for certification requests and certification request templates, new COSE headers, as well as a TLS certificate type and a file format for C509. This document updates RFC 6698 by extending the TLSA selectors registry to include C509 certificates. About This Document This note is to be removed before publishing as an RFC. Status information for this document may be found at https://datatracker.ietf.org/doc/draft-ietf-cose-cbor-encoded-cert/. Preuß Mattsson, et al. Expires 12 November 2026 [Page 1] Internet-Draft C509 Certificates May 2026 Discussion of this document takes place on the CBOR Object Signing and Encryption Working Group mailing list (mailto:cose@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/cose/. Subscribe at https://www.ietf.org/mailman/listinfo/cose/. Source for this draft and an issue tracker can be found at https://github.com/cose-wg/CBOR-certificates. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 12 November 2026. Copyright Notice Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Notational Conventions . . . . . . . . . . . . . . . . . . . 6 3. C509 Certificate . . . . . . . . . . . . . . . . . . . . . . 6 3.1. Message Fields . . . . . . . . . . . . . . . . . . . . . 7 3.2. Encoding of subjectPublicKey and issuerSignatureValue . . 13 3.3. Encoding of Extensions . . . . . . . . . . . . . . . . . 13 3.4. C509 COSE Header Parameters . . . . . . . . . . . . . . . 20 Preuß Mattsson, et al. Expires 12 November 2026 [Page 2] Internet-Draft C509 Certificates May 2026 3.5. C509 COSE Header Algorithm Parameters . . . . . . . . . . 21 3.6. Private Key Structures . . . . . . . . . . . . . . . . . 22 3.7. Deterministic Encoding . . . . . . . . . . . . . . . . . 23 3.8. C509 Name in TLS and DTLS . . . . . . . . . . . . . . . . 24 4. C509 Certification Request . . . . . . . . . . . . . . . . . 24 4.1. Certification Request Types . . . . . . . . . . . . . . . 25 4.2. Subject Signature Algorithm . . . . . . . . . . . . . . . 26 4.3. Certification Request Attributes . . . . . . . . . . . . 27 4.4. Certification Request Template . . . . . . . . . . . . . 27 5. C509 Processing and Certificate Issuance . . . . . . . . . . 29 6. Operational Considerations . . . . . . . . . . . . . . . . . 30 6.1. Legacy Considerations . . . . . . . . . . . . . . . . . . 30 6.2. Expected Certificate Sizes . . . . . . . . . . . . . . . 31 7. Security Considerations . . . . . . . . . . . . . . . . . . . 32 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 33 8.1. Designated Expert Guidance . . . . . . . . . . . . . . . 33 8.2. C509 Certificate Types Registry . . . . . . . . . . . . . 34 8.3. C509 Certification Request Types Registry . . . . . . . . 34 8.4. C509 Private Key Types Registry . . . . . . . . . . . . . 35 8.5. C509 Certification Request Templates Types Registry . . . 35 8.6. C509 RDN Attributes Registry . . . . . . . . . . . . . . 36 8.7. C509 CR Attributes Registry . . . . . . . . . . . . . . . 40 8.8. C509 Extensions Registry . . . . . . . . . . . . . . . . 41 8.9. C509 Certificate Policies Registry . . . . . . . . . . . 45 8.10. C509 Policies Qualifiers Registry . . . . . . . . . . . . 49 8.11. C509 Information Access Registry . . . . . . . . . . . . 49 8.12. C509 Extended Key Usages Registry . . . . . . . . . . . . 51 8.13. C509 General Names Registry . . . . . . . . . . . . . . . 53 8.14. C509 Signature Algorithms Registry . . . . . . . . . . . 55 8.15. C509 Public Key Algorithms Registry . . . . . . . . . . . 59 8.16. COSE Header Parameters Registry . . . . . . . . . . . . . 62 8.17. COSE Header Algorithm Parameters Registry . . . . . . . . 62 8.18. Media Type Application Registry . . . . . . . . . . . . . 62 8.19. CoAP Content-Formats Registry . . . . . . . . . . . . . . 68 8.20. TLS Certificate Types Registry . . . . . . . . . . . . . 70 8.21. TLSA Selectors Registry . . . . . . . . . . . . . . . . . 70 8.22. EDHOC Authentication Credential Types Registry . . . . . 71 8.23. Relative Distinguished Name Attribute . . . . . . . . . . 71 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 71 9.1. Normative References . . . . . . . . . . . . . . . . . . 71 9.2. Informative References . . . . . . . . . . . . . . . . . 75 Appendix A. C509 Certificate Examples . . . . . . . . . . . . . 79 A.1. Example: RFC 7925 profiled X.509 Certificate . . . . . . 79 A.2. Example: IEEE 802.1AR profiled X.509 Certificate . . . . 84 A.3. Example: CAB Baseline ECDSA HTTPS X.509 Certificate . . . 88 A.4. Example: CAB Baseline RSA HTTPS X.509 Certificate . . . . 90 A.5. Example: Certificate with Extensions IPAddrBlocks and IPAddrBlocksV2 . . . . . . . . . . . . . . . . . . . . . 93 Preuß Mattsson, et al. Expires 12 November 2026 [Page 3] Internet-Draft C509 Certificates May 2026 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 97 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 97 1. Introduction One of the challenges with deploying a Public Key Infrastructure (PKI) for the Internet of Things (IoT) is the size and parsing of X.509 public key certificates [RFC5280], since those are not optimized for constrained environments [RFC7228]. Large certificate chains are also problematic in non-constrained protocols such as EAP- TLS [RFC9190] [RFC9191] where authenticators typically drop an EAP session after only 40–50 round-trips, QUIC [RFC9000] where the latency increases significantly unless the server sends less than three times as many bytes as received prior to validating the client address, and Resource Public Key Infrastructure (RPKI) [RFC6487] where a single certificate can be very large. More compact certificate representations are, therefore, desirable in many use cases. X.509 certificates are defined using Abstract Syntax Notation One (ASN.1) and encoded using the Distinguished Encoding Rules (DER) [X.690]. This document specifies an alternative encoding of X.509 certificates using the Concise Binary Object Representation (CBOR) [RFC8949], initially proposed in [X.509-IoT]. The use of a more compact encoding reduces certificate size, which has known performance benefits in terms of decreased communication overhead, power consumption, latency, and storage requirements. The re- encoding of X.509 is called C509, and the resulting certificates are termed C509 certificates. C509 is not a general CBOR encoding for ASN.1 data structures. CBOR is a data format designed for small code size and small message size in systems with very limited memory, processor power, and instruction sets. CBOR builds on the JSON data model but extends it by, for example, encoding binary data directly without base64 conversion. In addition to the binary CBOR encoding, CBOR also has a diagnostic notation that is human-readable and editable, which simplifies development and debugging. The Concise Data Definition Language (CDDL) [RFC8610] provides a way to express structures for protocol messages and APIs that use CBOR. [RFC8610] also extends the diagnostic notation. For a complete specification and examples, see [RFC8949], [RFC8610], and [RFC8742]. A tool for becoming familiar with CBOR, available at the time of publication, is the CBOR playground [CborMe]. The C509 encoding supports a large subset of [RFC5280] and all certificates profiled for [RFC7925], IEEE 802.1AR (DevID) [IEEE-802.1AR], CAB Baseline [CAB-TLS], [CAB-Code], RPKI [RFC6487], Preuß Mattsson, et al. Expires 12 November 2026 [Page 4] Internet-Draft C509 Certificates May 2026 Wi-SUN [Wi-SUN], and eUICC [GSMA-eUICC]. C509 is designed for small code size and compact encoding of certificates in constrained environments including certificates profiled specifically for IoT deployments, but can be applied to certificate-based authentication in general, for example, using TLS [RFC8446], QUIC [RFC9000], DTLS [RFC9147], COSE [RFC9052] and EDHOC [RFC9528]. This document does not specify a certificate profile. At the time of publication, there are several C509 implementations targeting, for example, in-vehicle and vehicle-to-cloud communication, Uncrewed Aircraft Systems (UAS), and Global Navigation Satellite System (GNSS) deployments. When used to re-encode DER- encoded X.509 certificates, the CBOR encoding can reduce the size of [RFC7925]-profiled certificates by more than 50%; see Appendix A. C509 is designed to be extensible to additional X.509 features, for example, support for new algorithms, including new Post-Quantum (PQ) algorithms, which can be registered in the IANA registry as they are specified; see Section 8.14. This document defines two types of C509 using the same CBOR encoding and differing only in what is being signed: 1. An invertible CBOR re-encoding of DER-encoded X.509 certificates [RFC5280], which can be reversed to obtain the original DER- encoded X.509 certificate, which can be verified using legacy certificate software. Due to the widespread deployment of X.509, it is necessary to allow backward compatibility. 2. Natively signed C509 certificates, where the signature is calculated over the CBOR encoding instead of the DER encoding. This removes the need for ASN.1 and DER parsing and the associated complexity, but such certificates are not backward compatible with implementations requiring DER-encoded X.509. Natively signed C509 certificates can be used in devices that are only required to authenticate to servers compatible with natively signed C509 certificates. This is not a major restriction in many IoT deployments in which the parties that issue and verify certificates are part of a restricted ecosystem. This document also specifies C509 Certification Requests; see Section 4. It further specifies COSE headers for use with C509 certificates in COSE; see Section 8.16; a TLS certificate type for use with C509 certificates in TLS and QUIC, with or without additional TLS certificate compression; see Section 8.20; and a C509 file format. By extending the TLSA selectors registry to include C509 certificates, this document updates [RFC6698]. Preuß Mattsson, et al. Expires 12 November 2026 [Page 5] Internet-Draft C509 Certificates May 2026 2. Notational Conventions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. This specification makes use of the terminology in [RFC2986], [RFC5280], [RFC7228], [RFC8610], and [RFC8949]. When referring to CBOR, this specification always refers to Deterministically Encoded CBOR as specified in Sections 4.2.1 and 4.2.2 of [RFC8949]. 3. C509 Certificate This section specifies the content and encoding of C509 certificates, with the objective of producing a compact representation that supports a large part of [RFC5280] and all of [RFC7925], [IEEE-802.1AR], RPKI [RFC6487], GSMA eUICC [GSMA-eUICC], and CAB Baseline [CAB-TLS] [CAB-Code]. In the CBOR encoding, static fields are elided, elliptic curve points and time values are compressed, OIDs are replaced with short integers or complemented with CBOR OID encoding [RFC9090], and redundant encoding is removed. Combining these techniques significantly reduces certificate size, which is not achievable with general- purpose compression algorithms; see Figure 5. A C509 certificate can be either a CBOR re-encoding of a DER-encoded X.509 certificate, in which case the signature is calculated on the DER-encoded ASN.1 data in the X.509 certificate, or a natively signed C509 certificate, in which case the signature is calculated directly on the CBOR-encoded data. In both cases, the certificate content adheres to the restrictions given in [RFC5280]. The re-encoding is known to work with DER-encoded certificates, but it might also work with other canonical encodings. The re-encoding does not work for BER-encoded certificates. In the encoding described below, the elements in arrays are always encoded in the same order as elements of the corresponding SEQUENCE or SET in the DER encoding. Preuß Mattsson, et al. Expires 12 November 2026 [Page 6] Internet-Draft C509 Certificates May 2026 3.1. Message Fields This section describes the X.509 fields and their CBOR encodings and uses them in the definition of C509 certificates; see Figure 1. While many of [RFC5280] encodings are supported, there are a few instances marked "not supported" for which no alternative is provided and, therefore, no C509 encoding can be generated. The following Concise Data Definition Language (CDDL) defines the CBOR array C509Certificate and the CBOR Sequence [RFC8742] TBSCertificate. The member names therefore have documentary value only. Applications that do not require a CBOR item MAY represent C509 certificates using the CBOR sequence ~C509Certificate (unwrapped C509Certificate). Examples are given in the appendices; see, for example, Appendix A.1. Preuß Mattsson, et al. Expires 12 November 2026 [Page 7] Internet-Draft C509 Certificates May 2026 C509Certificate = [ TBSCertificate, issuerSignatureValue : any, ] ; The elements of the following group are used in a CBOR Sequence: TBSCertificate = ( c509CertificateType: int, certificateSerialNumber: CertificateSerialNumber, issuerSignatureAlgorithm: AlgorithmIdentifier, issuer: Name / null, validityNotBefore: ~time, validityNotAfter: ~time / null, subject: Name, subjectPublicKeyAlgorithm: AlgorithmIdentifier, subjectPublicKey: Defined, extensions: Extensions, ) CertificateSerialNumber = ~biguint Name = [ * RDNAttribute ] / SpecialText RDNAttribute = ( ( attributeType: int, attributeValue: SpecialText ) // ( attributeType: ~oid, attributeValue: bytes ) ) AlgorithmIdentifier = int / ~oid / [ algorithm: ~oid, parameters: bytes ] Extensions = [ * Extension ] / int Extension = ( ( extensionID: int, extensionValue: Defined ) // ( extensionID: ~oid, extensionValue: bytes / [ bytes ] ) ) SpecialText = text / bytes / tag Defined = any .ne undefined tag = #6 Figure 1: CDDL for C509Certificate. C509 certificates are defined in terms of DER-encoded X.509 certificates [RFC5280] as detailed in the following subsections. Preuß Mattsson, et al. Expires 12 November 2026 [Page 8] Internet-Draft C509 Certificates May 2026 3.1.1. version The 'version' field is encoded in the 'c509CertificateType' CBOR int. The field 'c509CertificateType' also indicates the type of the C509 certificate. Two types are defined in this document: natively signed C509 certificates, following X.509 v3 (c509CertificateType = 2); and CBOR re-encoded X.509 v3 DER certificate (c509CertificateType = 3), see Section 8.2. The number of elements in TBSCertificate is fixed and determined by the type. Additional types may be added in the future. 3.1.2. certificateSerialNumber The 'certificateSerialNumber' INTEGER value field is encoded as the unwrapped CBOR unsigned bignum (~biguint) 'CertificateSerialNumber'. Any leading 0x00 byte (to indicate that the number is not negative) is therefore omitted. 3.1.3. signature The 'signature' field, containing the signature algorithm including parameters, is encoded as a CBOR int (see Section 8.14) or as an array with an unwrapped CBOR OID tag [RFC9090] optionally followed by the parameters encoded as a CBOR byte string. 3.1.4. issuer In the general case, the sequence of 'RDNAttribute' is encoded as a CBOR array consisting of RDNAttribute elements. RelativeDistinguishedName with more than one AttributeTypeAndValue is not supported. Each RDNAttribute is CBOR-encoded as (type, value), either as an (int, SpecialText) pair or as a (~oid, bytes) tuple. Preuß Mattsson, et al. Expires 12 November 2026 [Page 9] Internet-Draft C509 Certificates May 2026 In the former case, the absolute value of the int encodes the attribute type (see Figure 10) and the sign is used to represent the character string type in the X.509 certificate; positive for utf8String, negative for printableString. Attribute values which are always of type IA5String are unambiguously represented using a non- negative int. Examples include emailAddress and domainComponent (see [RFC5280]). In CBOR, all text strings are UTF-8 encoded and in natively signed C509 certificates all CBOR ints SHALL be non- negative. Text strings SHALL still adhere to any [RFC5280] restrictions. The value of the attributes serialNumber and countryName SHALL contain only characters from the 74-character ASCII subset permitted by PrintableString. Additionally, the value of the countryName attribute SHALL have length 2. CBOR encoding is allowed for IA5String (if this is the only allowed type, e.g., emailAddress), printableString and utf8String, whereas the string types teletexString, universalString, and bmpString are not supported. The text strings are further optimized as follows: * If the text string has an even length of at least 2 and contains only the symbols '0'-'9' or 'a'-'f', it is encoded as a CBOR byte string. * If the text string contains an EUI-64 of the form "HH-HH-HH-HH-HH- HH-HH-HH" where each 'H' is one of the symbols '0'-'9' or 'A'-'F', it is encoded as a CBOR tagged MAC address using the CBOR tag 48, see Section 2.4 of [RFC9542]. If of the form "HH-HH-HH-FF-FE-HH- HH-HH", it is encoded as a 48-bit MAC address, otherwise as a 64-bit MAC address. See example in Appendix A.1. * Otherwise, it is encoded as a CBOR text string. The final encoding of the attribute value may therefore be text, bytes, or tag, i.e., SpecialText. If Name contains a single 'common name' attribute with attributeType = +1, it is for compactness encoded as just the SpecialText containing the single attribute value. In natively signed C509 certificates, bytes and tag 48 do not correspond to any predefined text string encoding and may also be used for other attribute types. If the 'issuer' field is identical to the 'subject' field, e.g., in case of self-signed certificates, then the 'issuer' field MUST be encoded as the CBOR simple value null (0xf6). Preuß Mattsson, et al. Expires 12 November 2026 [Page 10] Internet-Draft C509 Certificates May 2026 3.1.5. validity The 'notBefore' and 'notAfter' fields are encoded as unwrapped CBOR epoch-based date/time (~time) where the tag content is an unsigned integer. In POSIX time [POSIX], leap seconds are ignored, with a leap second having the same POSIX time as the second before it. Compression of X.509 certificates with the time 23:59:60 UTC is therefore not supported. Note that RFC 5280 mandates encoding of dates through the year 2049 as UTCTime, and later dates as GeneralizedTime. The value "99991231235959Z" (no expiration date) is encoded as the CBOR simple value null. 3.1.6. subject The 'subject' field is encoded exactly like issuer, except that the CBOR simple value null is not a valid value. 3.1.7. subjectPublicKeyInfo The 'AlgorithmIdentifier' field including parameters is encoded as the CBOR int 'subjectPublicKeyAlgorithm' (see Section 8.15) or as an array with an unwrapped CBOR OID tag [RFC9090] optionally followed by the parameters encoded as a CBOR byte string. In general, the 'subjectPublicKey' BIT STRING value field is encoded as a CBOR byte string, but may be encoded as a CBOR item of any type except undefined (see Section 4.4). This specification assumes the BIT STRING has zero unused bits, and the unused bits byte is omitted. For rsaEncryption and id-ecPublicKey, the encoding of subjectPublicKey is further optimized as described in Section 3.2. 3.1.8. issuerUniqueID Not supported. 3.1.9. subjectUniqueID Not supported. 3.1.10. extensions The 'extensions' field is encoded either as a CBOR array or as a CBOR int. An omitted 'extensions' field is encoded as an empty CBOR array. Each 'extensionID' in the CBOR array is encoded either as a CBOR int (see Section 8.8) or as an unwrapped CBOR OID tag [RFC9090]. Preuß Mattsson, et al. Expires 12 November 2026 [Page 11] Internet-Draft C509 Certificates May 2026 * If 'extensionID' is encoded as a CBOR int, it is followed by a CBOR item of any type except undefined (see Section 4.4), and the sign of the int is used to encode if the extension is critical: Critical extensions are encoded with a negative sign and non- critical extensions are encoded with a positive sign. If the CBOR array contains exactly two ints and the absolute value of the first int is 2 (corresponding to keyUsage, see Section 3.3), the CBOR array is omitted and the 'extensions' field is encoded as a single CBOR int with the absolute value of the second int and the sign of the first int. * If extensionID is encoded as an unwrapped CBOR OID tag, it is followed by the DER-encoded extnValue encoded in the following way: - if the extension is non-critical, the extnValue OCTET STRING value field is encoded as a CBOR byte string; - if the extension is critical, the extnValue OCTET STRING value field is encoded as a CBOR byte string and further wrapped in a CBOR array consisting of only this element. The processing of critical and non-critical extensions is specified in Section 4.2 of [RFC5280]. The currently defined extension values for which there is CBOR int encoded 'extensionID' are specified in Section 3.3. The extensions mandated to be supported by [RFC7925] and [IEEE-802.1AR] are given special treatment. More details about extensions in Section 3.3. 3.1.11. signatureAlgorithm The 'signatureAlgorithm' field is always the same as the 'signature' field and therefore omitted from the CBOR encoding. 3.1.12. signatureValue In general, the 'signatureValue' BIT STRING value field is encoded as the CBOR byte string issuerSignatureValue. This specification assumes that the BIT STRING has zero unused bits, and the unused bits byte is omitted. For natively signed C509 certificates, the signatureValue is calculated over the CBOR sequence TBSCertificate. For ECDSA, the encoding of issuerSignatureValue is further optimized as described in Section 3.2. Preuß Mattsson, et al. Expires 12 November 2026 [Page 12] Internet-Draft C509 Certificates May 2026 3.2. Encoding of subjectPublicKey and issuerSignatureValue 3.2.1. Encoding of subjectPublicKey For RSA public keys (rsaEncryption), the SEQUENCE and INTEGER type and length fields are omitted, and the two INTEGER value fields (modulus, exponent) are encoded as an array of two unwrapped CBOR unsigned bignum (~biguint), i.e., [ modulus : ~biguint, exponent : ~biguint ]. If the exponent is 65537, the array and the exponent are omitted and subjectPublicKey consists of only the modulus encoded as an unwrapped CBOR unsigned bignum (~biguint). For elliptic curve public keys in Weierstrass form (id-ecPublicKey), keys may be point-compressed as defined in Section 2.3.3 of [SECG]. Native C509 certificates with Weierstrass form keys use the octets 0x02, 0x03, and 0x04 as defined in [SECG]. If a DER-encoded certificate with an uncompressed public key of type id-ecPublicKey is CBOR-encoded with point compression, then the octet 0xfe is used instead of 0x02 to represent an even y-coordinate, and the octet 0xfd is used instead of 0x03 to represent an odd y-coordinate. 3.2.2. Encoding of issuerSignatureValue ECDSA signatures are encoded in the same way as in Section 2.1 of [RFC9053]. For example, for P-256, the number of bytes for each integer is 32. The resulting byte string is encoded as a CBOR byte string. 3.3. Encoding of Extensions The 'extensions' field is encoded as specified in Section 3.1.10 with further details provided in this section. For some extensions, the CBOR int encoded extensionID is only supported for commonly used values of the extension. In case of extension values for which the CBOR int encoded extensionID is not supported, the extension MUST be encoded using the unwrapped CBOR OID tag encoded extensionID. A note on extensionID naming: in existing OID databases, the same OID can be found in versions with and without an 'id-pe' or 'id-ce' prefix. We have excluded the prefix for the commonly used extensions defined in [RFC5280] and included them for extensions defined elsewhere. CBOR encoding of the following extension values is fully supported: Preuß Mattsson, et al. Expires 12 November 2026 [Page 13] Internet-Draft C509 Certificates May 2026 * Subject Key Identifier (subjectKeyIdentifier). In natively signed certificates, KeyIdentifier can, for example, be composed of the leftmost 160 bits of the SHA-256 hash of the CBOR encoded subjectPublicKey. Other methods of generating unique numbers can be used. The extensionValue is encoded as follows: KeyIdentifier = bytes SubjectKeyIdentifier = KeyIdentifier * Key Usage (keyUsage). The 'KeyUsage' BIT STRING is interpreted as an unsigned integer in network byte order and encoded as a CBOR int. See Section 3.1.10 for special encoding in case keyUsage is the only extension present. KeyUsage = uint * Policy Mappings (policyMappings). extensionValue is encoded as follows: PolicyMappings = [ + (issuerDomainPolicy: int/~oid, subjectDomainPolicy: int/~oid) ] * Basic Constraints (basicConstraints). If 'cA' = false then extensionValue = -2, if 'cA' = true and 'pathLenConstraint' is not present then extensionValue = -1, and if 'cA' = true and 'pathLenConstraint' is present then extensionValue = pathLenConstraint. BasicConstraints = int * Policy Constraints (policyConstraints). extensionValue is encoded as follows: PolicyConstraints = [ requireExplicitPolicy: uint / null, inhibitPolicyMapping: uint / null, ] * Extended Key Usage (extKeyUsage). extensionValue is encoded as an array of CBOR ints (see Section 8.12), or unwrapped CBOR OID tags [RFC9090], where each int or OID encodes a key usage purpose. If the array contains a single KeyPurposeId, the array is omitted. KeyPurposeId = int / ~oid ExtKeyUsageSyntax = [ 2* KeyPurposeId ] / KeyPurposeId Preuß Mattsson, et al. Expires 12 November 2026 [Page 14] Internet-Draft C509 Certificates May 2026 * Inhibit anyPolicy (inhibitAnyPolicy). extensionValue is encoded as follows: InhibitAnyPolicy = uint * IPAddrBlocks (id-pe-ipAddrBlocks). The X.509 extension IPAddrBlocks is specified in [RFC3779]. The ASN.1 BIT STRING value of IPAddress is converted to a byte sequence defined as: unusedBits || value where unusedBits is a single octet indicating the number of unused bits in the final octet of the BIT STRING, and value is the sequence of octets containing the BIT STRING value. This byte sequence preserves the exact information contained in the ASN.1 BIT STRING. For each IPAddressFamily, the representation is selected as follows: - If inherit is present, null SHALL be used. - Otherwise, if the byte sequence of any IPAddress (including addressPrefix, and the min and max fields of addressRange) exceeds 8 octets in length, the IPAddressChoice representation SHALL be used. - Otherwise, the IntIPAddressChoice representation SHALL be used. For IntIPAddressChoice, IntAddressPrefix and the min and max values of IntAddressRange SHALL be encoded as big-endian integers representing the following byte sequence: (unusedBits + 1) || value The first byte is encoded as (unusedBits + 1) instead of unusedBits in order to guarantee a non-zero value. With the exception of the first IPAddress, each subsequent IPAddress SHALL be encoded as a CBOR integer representing the difference from the previous IPAddress. As specified in [RFC3779], the IPAddressFamily element contains an Address Family Identifier (AFI) and, optionally, a Subsequent Address Family Identifier (SAFI). AFIs and SAFIs are defined in [IANA-AFI] and [IANA-SAFI], respectively. The limitations specified in [RFC3779] apply here as well. Preuß Mattsson, et al. Expires 12 November 2026 [Page 15] Internet-Draft C509 Certificates May 2026 IntAddressPrefix = int IntAddressRange = [ min: int, max: int ] IntIPAddressOrRange = IntAddressPrefix / IntAddressRange IntIPAddressChoice = [ + IntIPAddressOrRange ] AddressPrefix = bytes AddressRange = [ min: bytes, max: bytes ] IPAddressOrRange = AddressPrefix / AddressRange IPAddressChoice = [ + IPAddressOrRange ] IPAddressFamily = (AFI: uint, SAFI: uint / null, IntIPAddressChoice / IPAddressChoice / null) IPAddrBlocks = [ + IPAddressFamily ] * IPAddrBlocks v2 (id-pe-ipAddrBlocks-v2). The X.509 extension IPAddrBlocks v2 is specified in [RFC8360]. The extension value is encoded exactly like in the extension "IPAddrBlocks". * OCSP No Check (id-pkix-ocsp-nocheck). The CBOR encoded extensionValue is the value null. * TLS Features (id-pe-tlsfeature). The extensionValue is encoded as an array of integers, where each integer represents a TLS extension. TLSFeatures = [* feature: uint] CBOR encoding of the following extension values are partly supported: * Subject Alternative Name (subjectAltName). If the subject alternative name only contains general names registered in Section 8.13 the extension value can be CBOR encoded. extensionValue is encoded as an array of (int, any) pairs where each pair encodes a general name (see Section 8.13). If subjectAltName contains exactly one dNSName, the array and the int are omitted and extensionValue is the dNSName encoded as a CBOR text string. In addition to the general names defined in [RFC5280], the otherName values with type-id id-on- hardwareModuleName, id-on-SmtpUTF8Mailbox and id-on-MACAddress have been given their own ints; such otherName values are encoded as follows: - For id-on-hardwareModuleName, the value is a CBOR array [ hwType: ~oid, hwSerialNum: bytes ] as specified in [RFC4108]. - For id-on-SmtpUTF8Mailbox, the value is a CBOR text as specified in [RFC9598]. Preuß Mattsson, et al. Expires 12 November 2026 [Page 16] Internet-Draft C509 Certificates May 2026 - For id-on-MACAddress, the value is a CBOR byte string containing 6 octets for EUI-48 and 8 octets for EUI-64 as specified in [I-D.ietf-lamps-macaddress-on]. GeneralName = ( GeneralNameType : int, GeneralNameValue : any ) GeneralNames = [ + GeneralName ] SubjectAltName = GeneralNames / text * Issuer Alternative Name (issuerAltName). extensionValue is encoded exactly like subjectAltName. IssuerAltName = GeneralNames / text * CRL Distribution Points (cRLDistributionPoints). If all DistributionPoint elements contain the distributionPoint with fullName choice of uniformResourceIdentifier, optional reasons, and optional cRLIssuer with one directoryName, the extension value can be CBOR-encoded. The 'reasons' BIT STRING is interpreted as an unsigned integer in network byte order and encoded as a CBOR uint. If the CRLDistributionPoints consists of only one DistributionPointName, which in turn has only the fullName field of type CBOR text, it is encoded as CBOR text; otherwise it is encoded as a CBOR array. DistributionPointName = [ fullName: [ 2 * text ] / text, reasons: uint / null, cRLIssuer: Name / null, ] CRLDistributionPoints = [ + DistributionPointName ] / text * Freshest CRL (freshestCRL). extensionValue is encoded exactly like cRLDistributionPoints. FreshestCRL = CRLDistributionPoints * Authority Information Access (authorityInfoAccess). If all the GeneralNames in authorityInfoAccess are of type uniformResourceIdentifier, the extension value can be CBOR- encoded. Each accessMethod is encoded as a CBOR int (see Section 8.11) or an unwrapped CBOR OID tag [RFC9090]. The uniformResourceIdentifiers are encoded as CBOR text strings. AccessDescription = ( accessMethod: int / ~oid , uri: text ) AuthorityInfoAccessSyntax = [ + AccessDescription ] Preuß Mattsson, et al. Expires 12 November 2026 [Page 17] Internet-Draft C509 Certificates May 2026 * Subject Information Access (subjectInfoAccess). Encoded exactly like authorityInfoAccess. SubjectInfoAccessSyntax = AuthorityInfoAccessSyntax * Authority Key Identifier (authorityKeyIdentifier). If the authority key identifier contains all of keyIdentifier, authorityCertIssuer, and authorityCertSerialNumber, or if only keyIdentifier is present, the extension value can be CBOR-encoded. If all three are present, a CBOR array is used. If only keyIdentifier is present, the array is omitted: KeyIdentifierArray = [ keyIdentifier: KeyIdentifier, authorityCertIssuer: GeneralNames, authorityCertSerialNumber: CertificateSerialNumber, ] AuthorityKeyIdentifier = KeyIdentifierArray / KeyIdentifier * Certificate Policies (certificatePolicies). If noticeRef is not used and any explicitText values are encoded as UTF8String, the extension value can be CBOR-encoded. OIDs registered in Section 8.9 are encoded as an int. The policyQualifierId is encoded as a CBOR int (see Section 8.10) or an unwrapped CBOR OID tag [RFC9090]. PolicyIdentifier = int / ~oid PolicyQualifierInfo = ( policyQualifierId: int / ~oid, qualifier: text, ) CertificatePolicies = [ + ( PolicyIdentifier, [ * PolicyQualifierInfo ] ) ] * Name Constraints (nameConstraints). If the name constraints only contain general names registered in Section 8.13, the extension value can be CBOR-encoded. C509 uses the same additions and restrictions as defined in Section 2.2 of [RFC9549]. Note that the minimum and maximum fields are not used and are therefore omitted. For IPv4 addresses, the iPAddress field MUST contain five octets, and for IPv6 addresses, the field MUST contain 17 octets. In both cases the last octet indicates the number of bits in the prefix. As an example, the address block 192.0.2.0/24 is encoded as C0 00 02 00 18 instead of C0 00 02 00 FF FF FF 00 as in the DER encoding. Preuß Mattsson, et al. Expires 12 November 2026 [Page 18] Internet-Draft C509 Certificates May 2026 GeneralSubtrees = [ + GeneralName ] NameConstraints = [ permittedSubtrees: GeneralSubtrees / null, excludedSubtrees: GeneralSubtrees / null, ] * Subject Directory Attributes (subjectDirectoryAttributes). Encoded as attributes in issuer and subject with the difference that there can be more than one attributeValue. RDNAttributes = ( ( attributeType: int, attributeValue: [ + SpecialText] ) // ( attributeType: ~oid, attributeValue: [+ bytes] ) ) SubjectDirectoryAttributes = [ + RDNAttributes ] * AS Identifiers (id-pe-autonomousSysIds). The X.509 extension AS Identifiers is specified in [RFC3779]. If 'rdi' is not present, the extension value can be CBOR-encoded. Each ASId is encoded as a CBOR uint. With the exception of the first ASId, each subsequent ASId is encoded as the difference from the previous ASId. ASIdOrRange = uint / [min:uint, max:uint] ASIdentifiers = [ + ASIdOrRange ] / null * AS Identifiers v2 (id-pe-autonomousSysIds-v2). The X.509 extension AS Identifiers v2 is specified in [RFC8360]. The extension value is encoded exactly like in the extension "AS Identifiers". 3.3.1. Example Encoding of Extensions The examples below use values from Section 8.8, Section 8.12, and Section 8.13: * A critical basicConstraints ('cA' = true) without pathLenConstraint is encoded as the two CBOR ints -4, -1. * A non-critical keyUsage with digitalSignature (0), nonRepudiation (1), keyEncipherment (2) and keyAgreement (4) asserted is encoded as the two CBOR ints 2, 23 (2^0 + 2^1 + 2^2 + 2^4 = 23). * A non-critical extKeyUsage containing id-kp-codeSigning and id-kp- OCSPSigning is encoded as the CBOR int 8 followed by the CBOR array [ 3, 9 ]. Preuß Mattsson, et al. Expires 12 November 2026 [Page 19] Internet-Draft C509 Certificates May 2026 * A non-critical subjectAltName containing only the dNSName example.com is encoded as the CBOR int 3 followed by the CBOR text string "example.com". Thus, the extension field of a certificate containing all of the above extensions in the given order would be encoded as the CBOR array [ -4, -1, 2, 23, 8, [ 3, 9 ], 3, "example.com" ]. 3.4. C509 COSE Header Parameters The formatting and processing for c5b, c5c, c5t, and c5u, defined in Table 1 below, are similar to x5bag, x5chain, x5t, x5u defined in [RFC9360] except that the certificates are C509 instead of DER- encoded X.509 and use a COSE_C509 structure instead of COSE_X509. The COSE_C509 structure used in c5b, c5c, and c5u is defined as: COSE_C509 = C509CertData / [ 2* C509CertData ] C509CertData = bytes .cborseq C509Certificate C509CertData thus includes the unwrapped CBOR sequence, ~C509Certificate. The byte string encoding includes the length of each certificate, which simplifies parsing. See Appendix A.1.5 for an example. The COSE_C509 item has media type application/cose-c509-cert, see Section 8.18.1. Different CoAP Content-Formats are defined depending on "usage" = "chain" or not, see Section 8.19. Stored file formats are defined for the cases with/without ("usage" = "chain") with "magic numbers" TBD8/TBD6 using the reserved CBOR tag 55799 and the corresponding Content-Formats TBD15/TBD3, enveloped as described in Section 2.2 of [RFC9277]. The value type of c5t is the COSE_CertHash structure defined in [RFC9360], which contains the hash value of the C509 certificate calculated over ~C509Certificate. Thus, C509CertData contains all data necessary to calculate the thumbprint c5t. c5u provides an alternative way to identify an untrusted certificate chain by reference with a URI [RFC3986], encoded as a CBOR text string (media type application/cbor and CoAP Content-Format 60). The referenced resource is a COSE_C509 item served with the application/ cose-c509-cert media type ("usage" = "chain"), as described above. Preuß Mattsson, et al. Expires 12 November 2026 [Page 20] Internet-Draft C509 Certificates May 2026 As the contents of c5b, c5c, c5t, and c5u are untrusted input, the header parameters can be in either the protected or unprotected header bucket. The trust mechanism MUST process any certificates in the c5b, c5c, and c5u parameters as untrusted input. The presence of a self-signed certificate in the parameter MUST NOT cause the update of the set of trust anchors without appropriate authorization. +======+=======+===============+=============================+ | Name | Label | Value Type | Description | +======+=======+===============+=============================+ | c5b | 24 | COSE_C509 | An unordered bag of C509 | | | | | certificates | +------+-------+---------------+-----------------------------+ | c5c | 25 | COSE_C509 | An ordered chain of C509 | | | | | certificates | +------+-------+---------------+-----------------------------+ | c5t | 22 | COSE_CertHash | Hash of a ~C509Certificate | +------+-------+---------------+-----------------------------+ | c5u | 23 | uri | URI pointing to a COSE_C509 | | | | | containing an ordered chain | | | | | of certificates | +------+-------+---------------+-----------------------------+ Table 1: C509 COSE Header Parameters Certificates can also be identified with a 'kid' header parameter by storing the 'kid' value and the associated bag or chain in a dictionary. 3.5. C509 COSE Header Algorithm Parameters This section defines the COSE header parameters used for identifying or transporting the sender's key for static-static key agreement algorithms corresponding to Section 3 of [RFC9360], see Table 2. * c5c-sender contains the chain of certificates starting with the sender's key exchange certificate. The structure is the same as 'c5c'. * c5t-sender contains the hash value for the sender's key exchange certificate. The structure is the same as 'c5t'. * c5u-sender contains a URI for the sender's key exchange certificate. The structure and processing are the same as 'c5u'. Preuß Mattsson, et al. Expires 12 November 2026 [Page 21] Internet-Draft C509 Certificates May 2026 +======+==========+=============+===============+==================+ | Name|Algorithm | Label | Type | Description | +======+==========+=============+===============+==================+ | c5c-|ECDH- | -30 | COSE_C509 | An ordered chain | |sender|SS+HKDF- | (suggested) | | of C509 | | |256, ECDH-| | | certificates | | |SS+HKDF- | | | | | |512, ECDH-| | | | | |SS+A128KW,| | | | | |ECDH- | | | | | |SS+A192KW,| | | | | |ECDH- | | | | | |SS+A256KW | | | | +------+----------+-------------+---------------+------------------+ | c5t-|ECDH- | -31 | COSE_CertHash | Hash of a | |sender|SS+HKDF- | (suggested) | | ~C509Certificate | | |256, ECDH-| | | | | |SS+HKDF- | | | | | |512, ECDH-| | | | | |SS+A128KW,| | | | | |ECDH- | | | | | |SS+A192KW,| | | | | |ECDH- | | | | | |SS+A256KW | | | | +------+----------+-------------+---------------+------------------+ | c5u-|ECDH- | -32 | uri | URI pointing to | |sender|SS+HKDF- | (suggested) | | a COSE_C509 | | |256, ECDH-| | | containing an | | |SS+HKDF- | | | ordered chain of | | |512, ECDH-| | | certificates | | |SS+A128KW,| | | | | |ECDH- | | | | | |SS+A192KW,| | | | | |ECDH- | | | | | |SS+A256KW | | | | +------+----------+-------------+---------------+------------------+ Table 2: Static ECDH Algorithm Values 3.6. Private Key Structures Certificate management also makes use of data structures including private keys; see, e.g., [RFC7468]. This section defines the following CBOR-encoded structures: Preuß Mattsson, et al. Expires 12 November 2026 [Page 22] Internet-Draft C509 Certificates May 2026 C509PrivateKey = [ C509PrivateKeyType: int, subjectPrivateKeyAlgorithm: AlgorithmIdentifier, subjectPrivateKey: any, ] The field 'C509PrivateKeyType' indicates the type of the C509 private key. Different types of C509 Private Key Structures can be defined, see Section 8.4. Currently, two types are defined. When C509PrivateKeyType = 0, the subjectPrivateKey is the CBOR byte string encoding of the PrivateKey OCTET STRING value field defined in [RFC5958]. When C509PrivateKeyType = 1, the subjectPrivateKey is a COSE_KEY structure containing a private key as defined in [RFC9052]. Note that COSE_KEY might not be possible to use with all algorithms that have a C509 AlgorithmIdentifier defined. The C509PrivateKey item is served with the application/cose- c509-privkey media type, see Section 8.18.4, with corresponding CoAP Content-Format defined in Section 8.19. A stored file format is defined with "magic number" TBD12 using the reserved CBOR tag 55799 and the Content-Format TBD10, enveloped as described in Section 2.2 of [RFC9277]. C509PEM = [ C509PrivateKey, COSE_C509 / null, ] The C509PEM item is served with the application/cose-c509-pem media type, see Section 8.18.5, with corresponding CoAP Content-Format defined in Section 8.19. A stored file format is defined with "magic number" TBD13 using the reserved CBOR tag 55799 and the Content- Format TBD11, enveloped as described in Section 2.2 of [RFC9277]. 3.7. Deterministic Encoding In some use cases it is desirable to be able to specify a unique C509 representation of a given X.509 certificate. Although this specification requires the use of Deterministically Encoded CBOR (see Section 2), it is still possible to represent certain X.509 certificate fields in different ways. This is a consequence of the extensibility of the C509 format, in which new encodings can be defined, for example, to optimize extensions for which no special CBOR encoding has previously been defined. Preuß Mattsson, et al. Expires 12 November 2026 [Page 23] Internet-Draft C509 Certificates May 2026 Where both a specific and a generic CBOR encoding are supported, the specific CBOR encoding MUST be used. For example, when a specific CBOR encoding of an extension is defined in Section 3.3 and the C509 Extensions Registry, that specific encoding MUST be used. In particular, when a specific otherName encoding is available, identified by a negative integer value in the C509 General Names Registry, it MUST be used. Native C509 certificates MUST use only specific CBOR-encoded fields. However, when decoding non-native C509 certificates, the decoder may need to support, for example, the (extensionID: ~oid, extensionValue: bytes / [bytes]) encoding of an extension for which an (extensionID: int, extensionValue: Defined) encoding exists. One reason is that the certificate might have been issued before the specific CBOR extension was registered. 3.8. C509 Name in TLS and DTLS In TLS and DTLS, the subject of a trusted authority may be sent to the peer to help it select the certificate chain, as in the CertificateAuthoritiesExtension in [RFC8446], in the certificate_authorities field of CertificateRequest in [RFC5246], or in the TrustedAuthorities in [RFC6066]. For such usage in TLS and DTLS, the C509 name is wrapped in a distinguished name [X.501] with exactly one RelativeDistinguishedName, which in turn contains exactly one AttributeTypeAndValue with the attribute C509Name. The attribute value is the raw byte string of the encoded C509 Name as specified in Section 3.1.6. The attribute for C509 Name has the following structure: id-rdna-c509Name OBJECT IDENTIFIER ::= { 1 3 6 1 5 5 7 25 TBD30 } c509Name ATTRIBUTE ::= { WITH SYNTAX C509Name SINGLE VALUE TRUE ID id-rdna-c509Name } C509Name ::= OCTET STRING 4. C509 Certification Request This section defines the format of a C509 Certification Request based on [RFC2986]. It reuses the encodings of C509 certificates defined in Section 3. A Certification Request is commonly referred to as a Certificate Signing Request (CSR). Preuß Mattsson, et al. Expires 12 November 2026 [Page 24] Internet-Draft C509 Certificates May 2026 The CDDL for the C509 Certification Request is shown in Figure 2. The fields have the same encoding as the corresponding fields of the C509 Certificate, see Section 3.1. C509CertificationRequest = [ TBSCertificationRequest, subjectSignatureValue: any, ] ; The elements of the following group are used in a CBOR Sequence: TBSCertificationRequest = ( c509CertificationRequestType: int, subjectSignatureAlgorithm: AlgorithmIdentifier, subject: Name, subjectPublicKeyAlgorithm: AlgorithmIdentifier, subjectPublicKey: Defined, attributes: CRAttributes, ) CRAttributes = [ * CRAttribute ] CRAttribute = (( attributeType: int, attributeValue: Defined ) // ( attributeType: ~oid, attributeValue: bytes )) Figure 2: CDDL for C509CertificationRequest. After verifying subjectSignatureValue, the Certification Authority (CA) MAY transform the C509CertificationRequest into a [RFC2986] CertificationRequestInfo for compatibility with existing procedures and implementations. The media type of C509CertificationRequest is application/cose- c509-pkcs10, see Section 8.18.2, with corresponding CoAP Content- Format defined in Section 8.19. The "magic number" TBD9 is defined using the reserved CBOR tag 55799 and the Content-Format TBD4, enveloped as described in Section 2.2 of [RFC9277]. 4.1. Certification Request Types Two types of C509 Certification Requests are defined. Both use the same CBOR encoding and differ only in what is being signed; see Section 8.3. A C509 Certification Request is either an invertible CBOR re-encoding of a DER-encoded certification request [RFC2986] or a natively signed request in which the signature is calculated over the CBOR encoding instead of the DER encoding. Preuß Mattsson, et al. Expires 12 November 2026 [Page 25] Internet-Draft C509 Certificates May 2026 * c509CertificationRequestType = 2. This type indicates that the C509 Certification Request is natively signed, i.e., that subjectSignatureValue contains the signature over the CBOR Sequence TBSCertificationRequest; see Figure 2. This encoding removes the need for ASN.1 and DER parsing and for re-encoding by the requesting party. * c509CertificationRequestType = 3. This type indicates that the C509 Certification Request is a CBOR re-encoded [RFC2986] certification request, as defined in Section 4. This encoding is backward compatible with legacy RFC 2986 certification requests and reduces transport overhead. The type of certificate issued in response to the request is determined by the application. For C509, the default is c509CertificateType = c509CertificationRequestType. An implementation MAY only support certain values of c509CertificationRequestType. 4.2. Subject Signature Algorithm subjectSignatureAlgorithm can be a signature algorithm or a non- signature proof-of-possession algorithm, for example, as defined in [RFC6955]. In the case of [RFC6955], the signature is replaced by a MAC and requires a public Diffie-Hellman key of the verifier to be distributed out of band. Both signature algorithms and non-signature proof-of-possession algorithms are listed in the C509 Signature Algorithms Registry; see Section 8.14. The non-signature proof-of- possession algorithms with SHA-2 and HMAC-SHA2 (see values 14-16 in Section 8.14) require a signature value with syntax DhSigStatic, defined as follows: DhSigStatic = MessageDigest / DhSigStaticType MessageDigest = bytes DhSigStaticType = [ issuer: Name, certificateSerialNumber: CertificateSerialNumber, hashValue: MessageDigest, ] Note that a key agreement key pair may be used with a signature algorithm in a certification request, see Appendix A.1.3. Preuß Mattsson, et al. Expires 12 November 2026 [Page 26] Internet-Draft C509 Certificates May 2026 4.3. Certification Request Attributes The 'attributes' field specifies the attributes contained in a certification request. The 'attributes' field with no GeneralAttribute SHALL be encoded as an empty CBOR array. The remainder of this section specifies CBOR-encoded attributes for Certification Requests. 4.3.1. Extension Request The X.509 attribute "Extension Request" is defined in [RFC2985]. The 'attributeValue' field has type Extensions as in Section 3.1. An empty CBOR array indicates no extensions. 4.3.2. Challenge Password The X.509 attribute "Challenge Password" is defined in [RFC2985]. The 'attributeValue' field has type ChallengePassword. A UTF8 String is encoded as CBOR text, and a Printable String is tagged with number 121 (alternative 0 as defined in [IANA-CBOR-TAGS]). All other string types are not supported. For certification request type 2, only UTF8 String is allowed. ChallengePassword = text / #6.121(text) 4.3.3. Private Key Possession Statement The X.509 attribute "Statement of Possession of a Private Key" is defined in [RFC9883]. The 'attributeValue' field has type PrivateKeyPossessionStatement. PrivateKeyPossessionStatement = [ issuer: Name, certificateSerialNumber: CertificateSerialNumber, cert: C509Certificate / null, ] 4.4. Certification Request Template Enrollment over Secure Transport (EST, [RFC7030]) defines, and [RFC9908] clarifies, how an EST server can specify what it expects the EST client to include in a subsequent Certification Request. Alternatively to the unstructured mechanism specified in [RFC7030], Appendix B of [RFC8295] describes an approach using a Certification Request Template in response to a GET /csrattrs request by the EST client. The EST server thus returns a Certification Request-like object with various fields filled out, and other fields waiting to be Preuß Mattsson, et al. Expires 12 November 2026 [Page 27] Internet-Draft C509 Certificates May 2026 filled in and a signature to be added by the EST client. The approach of [RFC8295] is also followed for C509. The C509CertificationRequestTemplate is based on TBSCertificationRequest of the C509CertificationRequest, see Figure 2, but excludes the subjectSignatureValue field from the template since that needs no further specification. The C509 Certification Request Template is shown in Figure 3. C509CertificationRequestTemplate = [ c509CertificationRequestTemplateType: int, c509CertificationRequestType: [+ int] / undefined, subjectSignatureAlgorithm: [+ AlgorithmIdentifier] / undefined, subject: NameTemplate / undefined, subjectPublicKeyAlgorithm: [+ AlgorithmIdentifier] / undefined, subjectPublicKey: undefined, extensionsRequest: ExtensionsTemplate / undefined, ] NameTemplate = [ * RDNAttributeTemplate ] RDNAttributeTemplate = ( ( attributeType: uint, minOccurs: uint, maxOccurs: uint, attributeValue: SpecialText / undefined ) // ( attributeType: ~oid, minOccurs: uint, maxOccurs: uint, attributeValue: bytes / undefined ) ) ExtensionsTemplate = [ * ExtensionTemplate ] ExtensionTemplate = ( ( extensionID: uint, optional: bool, extensionValue: any ) // ( extensionID: ~oid, optional: bool, extensionValue: bytes / undefined ) ) Figure 3: CDDL for C509CertificationRequestTemplate. Except as specified in this section, the fields have the same encoding as the corresponding fields of the TBSCertificationRequest, see Figure 2. The specification of the template makes use of the CBOR simple value undefined (0xf7) to indicate fields to fill in. Consistent with this rule, note that the subjectPublicKey field always has the value undefined in the template. Preuß Mattsson, et al. Expires 12 November 2026 [Page 28] Internet-Draft C509 Certificates May 2026 Different types of Certification Request Templates can be defined (see Section 8.5), distinguished by the c509CertificationRequestTemplateType integer. Each type may have its own CDDL structure. The presence of a Defined (non-undefined) value in a C509CertificationRequestTemplate indicates that the server expects the client to use that value in the certification request. If multiple AlgorithmIdentifier or c509CertificationRequestType values are present, the server expects the client to select one of them for use in the Certification Request. The presence of an undefined value indicates that the client is expected to provide an appropriate value for that field. For example, if the server includes a subjectAltName with a GeneralNameType iPAddress and a GeneralNameValue empty byte string, this means that the client SHOULD fill in a corresponding GeneralNameValue. For RDNAttributeTemplate, the minOccurs and maxOccurs fields specify the minimal and maximal occurrences of attributes of the given attributeType; maximal shall not be less than minimal, and maximal shall be positive. Negative attributeType is not allowed. For ExtensionTemplate, the field "optional" specifies whether an extension of the given extensionID is optional. Negative extensionID is not allowed. The media type of C509CertificationRequestTemplate is application/ cose-c509-crtemplate, see Section 8.18.3, with corresponding CoAP Content-Format defined in Section 8.19. The "magic number" TBD18 is defined using the reserved CBOR tag 55799 and the Content-Format TBD19, enveloped as described in Section 2.2 of [RFC9277]. 5. C509 Processing and Certificate Issuance It is straightforward to integrate the C509 format into legacy X.509 processing during certificate issuance. C509 processing can be performed as an isolated function of the CA, or as a separate function trusted by the CA. The Certification Request format defined in Section 4 follows the PKCS#10 format to enable a direct mapping to the certification request information, see Section 4.1 of [RFC2986]. The CA can make use of a Certification Request Template defined in Section 4.4, for simplified configuration. Preuß Mattsson, et al. Expires 12 November 2026 [Page 29] Internet-Draft C509 Certificates May 2026 When a certification request is received, the CA, or function trusted by the CA, needs to perform some limited C509 processing and verify the proof-of-possession corresponding to the public key, before normal certificate generation can take place. In the reverse direction, in case c509CertificateType = 3 was requested, a separate C509 processing function can perform the conversion from a generated X.509 certificate to C509 as a bump-in- the-wire. In case c509CertificateType = 2 was requested, the C509 processing needs to be performed before signing the certificate, in which case a tighter integration with the CA may be needed. 6. Operational Considerations 6.1. Legacy Considerations C509 certificates can be deployed with legacy X.509 certificates and CA infrastructure. An existing CA can continue to use its existing procedures and code for PKCS#10, and DER-encoded X.509 and only implement C509 as a thin processing layer on top. When receiving a C509 Certification Request, the CA transforms it into a DER-encoded CertificationRequestInfo [RFC2986] and uses that with existing processes and code to produce an RFC 5280 DER-encoded X.509 certificate. The DER-encoded X.509 is then transformed into a C509 certificate. At any later point, the C509 certificate can be used to recreate the original X.509 data structure needed to verify the signature. For protocols like TLS/DTLS 1.2, where certificates are sent unencrypted, the actual encoding and compression can be done at different locations depending on the deployment setting. For example, the mapping between C509 certificate and standard X.509 certificate can take place in a 6LoWPAN border gateway, which allows the server side to stay unmodified. This case gives the advantage of the low overhead of a C509 certificate over constrained wireless links. The conversion to X.509 within a constrained IoT device will incur a computational overhead. However, measured in energy, this is likely to be negligible compared to the reduced communication overhead. For the setting with constrained server and server-only authentication, the server only needs to be provisioned with the C509 certificate and does not perform the conversion to X.509. This option is viable when client authentication can be asserted by other means. Preuß Mattsson, et al. Expires 12 November 2026 [Page 30] Internet-Draft C509 Certificates May 2026 For protocols like IKEv2, TLS/DTLS 1.3, and EDHOC, where certificates are encrypted, the proposed encoding needs to be done fully end-to- end, through adding the encoding/decoding functionality to the server. 6.2. Expected Certificate Sizes The CBOR encoding of the sample certificate chains given in Appendix A results in the numbers shown in Figures 4 and 5. COSE_X509 is defined in [RFC9360] and COSE_C509 is defined in Section 8.16. After [RFC7925] profiling, most duplicated information has been removed, and the remaining text strings are minimal in size. Therefore, the further size reduction reached with general compression mechanisms such as Brotli [RFC7932] will be small, mainly corresponding to making the ASN.1 encoding more compact. CBOR encoding can however significantly compress RFC 7925 profiled certificates. In the examples with HTTPS certificate chains (www.ietf.org (ECDSA) and cabforum.org (RSA)) both C509 and Brotli perform well complementing each other. C509 uses dedicated information to compress individual certificates, while Brotli can compress duplicate information in the entire chain. Note that C509 certificates of type 2 and 3 have the same size. For Brotli, the Rust crate Brotli 3.3.0 was used with compression level 11 and window size 22. In the examples using FN-DSA and ML-DSA certificate chains, the largest portion of the certificate size consists of the public keys and signatures, which are essentially random. As a result, both Brotli and C509 achieve only very limited size reduction. However, C509 still performs slightly better. +----------------------------------------+-----------+-----------+ | Description (number of certs) | COSE_X509 | COSE_C509 | +----------------------------------------+-----------+-----------+ | RFC 7925 profiled IoT Certificate (1) | 319 | 142 | +----------------------------------------+-----------+-----------+ | RPKI Certificate (1) | 20981 | 11523 | +----------------------------------------+-----------+-----------+ | ECDSA HTTPS Certificate Chain (2) | 1644 | 1012 | +----------------------------------------+-----------+-----------+ | RSA HTTPS Certificate Chain (2) | 2909 | 2240 | +----------------------------------------+-----------+-----------+ | FN-DSA-512 HTTPS Certificate Chain (2) | 4417 | 3897 | +----------------------------------------+-----------+-----------+ | ML-DSA-65 HTTPS Certificate Chain (2) | 11863 | 11318 | +----------------------------------------+-----------+-----------+ Preuß Mattsson, et al. Expires 12 November 2026 [Page 31] Internet-Draft C509 Certificates May 2026 Figure 4: Comparing Sizes of Certificate Chains in COSE. Number of bytes (length of certificate chain). +-----------------------+-------+---------+-------+--------+ | Description | X.509 | X.509 + | C509 | C509 + | | (number of certs) | | Brotli | | Brotli | +-----------------------+-------+---------+-------+--------+ | RFC 7925 profiled | 325 | 317 | 149 | 158 | | IoT Certificate (1) | | | | | +-----------------------+-------+---------+-------+--------+ | RPKI Certificate (1) | 20987 | 9109 | 11529 | 7020 | +-----------------------+-------+---------+-------+--------+ | ECDSA HTTPS | 1651 | 1181 | 1019 | 930 | | Certificate Chain (2) | | | | | +-----------------------+-------+---------+-------+--------+ | RSA HTTPS | 2656 | 2195 | 2071 | 1913 | | Certificate Chain (2) | | | | | +-----------------------+-------+---------+-------+--------+ | FN-DSA-512 HTTPS | 4437 | 4026 | 3917 | 3776 | | Certificate Chain (2) | | | | | +-----------------------+-------+---------+-------+--------+ | ML-DSA-65 HTTPS | 11869 | 11420 | 11325 | 11148 | | Certificate Chain (2) | | | | | +-----------------------+-------+---------+-------+--------+ Figure 5: Comparing Sizes of Certificate Chains with TLS 1.3. Number of bytes (length of certificate chain). X.509 and C509 are Certificate messages. X.509 + Brotli and C509 + Brotli are CompressedCertificate messages. 7. Security Considerations The CBOR encoding of X.509 certificates does not change the security assumptions needed when deploying standard X.509 certificates. The same security procedures applies as for X.509. For example the same certificate path validation as defined in Section 6 of [RFC5280] MUST be performed on C509 certificates before they can be considered trusted. The security considerations of [RFC5280] apply. The use of natively signed C509 certificates removes the need for ASN.1 encoding, which is a rich source of security vulnerabilities. Conversion between the certificate formats can be made in constant time to reduce risk of information leakage through side channels. Preuß Mattsson, et al. Expires 12 November 2026 [Page 32] Internet-Draft C509 Certificates May 2026 The mechanism in this document does not reveal any additional information compared to X.509. Because of the difference in size, it will be possible to detect that this profile is used. The gateway solution described in Section 6.1 requires unencrypted certificates which may violate identity protection and is not recommended. Any issues with decoding or parsing a C509 certificate should be handled exactly as how such errors would be handled for the corresponding X.509 certificate. For example, a non-critical extension MAY be ignored if it is not recognized, see Section 4.2 of [RFC5280]. As stated in Section 3.4, the contents of the COSE Header Parameters c5b, c5c, c5t, c5u is untrusted input that potentially may be verified using existing trust anchors or other trust establishment mechanism out of scope of this document. Similar security considerations as x5bag, x5chain, x5t and x5u apply, see [RFC9360]. Security considerations of the COSE protected and unprotected headers are discussed in [RFC9052]. The specification makes no recommendations on the use of algorithms, paddings, or other security constructs applied in the encoding of a certificate. In particular, an IANA registration does not imply a recommendation. For example, some deprecated algorithms are assigned code points only for backward compatibility to enable CBOR encoding of existing certificates. 8. IANA Considerations This document creates several new registries in the new registry group "CBOR Encoded X.509 (C509)". For all items, the 'Reference' field points to this document. Editor's note: Add informative reference to the newly created IANA registries and updated existing registries. 8.1. Designated Expert Guidance Reviewers are encouraged to get sufficient information for registration requests to ensure that the usage is not going to duplicate one that is already registered and that the point is likely to be used in deployments. Experts should take into account the expected usage of entries when approving point assignment. The length of the encoded value should be weighed against the number of code points left that encode to that size and how constrained the systems it will be used on are. Values in the interval [-24, 23] have a 1-byte encoding, other values in the interval [-256, 255] have a 2-byte encoding, and the remaining values in the interval [-65536, Preuß Mattsson, et al. Expires 12 November 2026 [Page 33] Internet-Draft C509 Certificates May 2026 65535] have a 3-byte encoding. All assignments according to "IETF Review with Expert Review" are made on an "IETF Review" basis per Section 4.8 of [RFC8126] with "Expert Review" additionally required per Section 4.5 of [RFC8126]. The procedure for early IANA allocation of "standards track code points" defined in [RFC7120] also applies. When such a procedure is used, IANA will ask the designated expert(s) to approve the early allocation before registration. In addition, working group chairs are encouraged to consult the expert(s) early during the process outlined in Section 3.1 of [RFC7120]. 8.2. C509 Certificate Types Registry IANA has created a new registry titled "C509 Certificate Types" under the registry group "CBOR Encoded X.509 (C509)". The fields of the registry are Value, Description, and Reference, where Value is an integer, and the other columns are text strings. It is mandatory to specify content in all columns. For values in the interval [-24, 23], the registration procedure is "IETF Review with Expert Review". For all other values, the registration procedure is "Expert Review". The initial contents of the registry are (see Section 3.1.1): +-------+-------------------------------------------+ | Value | Description | +=======+===========================================+ | 0 | Reserved | +-------+-------------------------------------------+ | 1 | Reserved | +-------+-------------------------------------------+ | 2 | Natively Signed C509 Certificate | +-------+-------------------------------------------+ | 3 | CBOR Re-encoded X.509 v3 Certificate | +-------+-------------------------------------------+ Figure 6: C509 Certificate Types 8.3. C509 Certification Request Types Registry IANA has created a new registry titled "C509 Certification Request Types" under the new registry group "CBOR Encoded X.509 (C509)". The fields of the registry are Value, Description, and Reference, where Value is an integer, and the other columns are text strings. All columns are mandatory. For values in the interval [-24, 23] the registration procedure is "IETF Review with Expert Review". For all other values the registration procedure is "Expert Review". The initial contents of the registry are: Preuß Mattsson, et al. Expires 12 November 2026 [Page 34] Internet-Draft C509 Certificates May 2026 +-------+-----------------------------------------------------------+ | Value | Description | +=======+===========================================================+ | 0 | Reserved | +-------+-----------------------------------------------------------+ | 1 | Reserved | +-------+-----------------------------------------------------------+ | 2 | Natively Signed C509 Certification Request. | +-------+-----------------------------------------------------------+ | 3 | CBOR re-encoding of RFC 2986 certification request. | +-------+-----------------------------------------------------------+ Figure 7: C509 Certification Request Types 8.4. C509 Private Key Types Registry IANA has created a new registry titled "C509 Private Key Types" in the new registry group "CBOR Encoded X.509 (C509)". The fields of the registry are Value, Comments, subjectPrivateKey, and Reference, where Value is an integer, and the other columns are text strings. The subjectPrivateKey describes the encoding of the subject private key, see Section 3.6. All columns are mandatory. For values in the interval [-24, 23] the registration procedure is "IETF Review with Expert Review". For all other values the registration procedure is "Expert Review". The initial contents of the registry are: +-------+-----------------------------------------------------------+ | Value | Private Key | +=======+===========================================================+ | 0 | Comments: Asymmetric Key Package (RFC 5958) | | | subjectPrivateKey: PrivateKey OCTET STRING encoded as | | | CBOR byte string | +-------+-----------------------------------------------------------+ | 1 | Comments: COSE Key Object (RFC 9052) | | | subjectPrivateKey: COSE_Key containing a private key | +-------+-----------------------------------------------------------+ Figure 8: C509 Private Key Types 8.5. C509 Certification Request Templates Types Registry IANA has created a new registry titled "C509 Certification Request Templates Types" under the new registry group "CBOR Encoded X.509 (C509)". The columns of the registry are Value, Description, and Reference, where Value is an integer, and the other columns are text strings. All columns are mandatory. For values in the interval [-24, 23] the registration procedure is "IETF Review with Expert Review". For all other values the registration procedure is "Expert Preuß Mattsson, et al. Expires 12 November 2026 [Page 35] Internet-Draft C509 Certificates May 2026 Review". The initial contents of the registry are: +-------+-----------------------------------------------------------+ | Value | Description | +=======+===========================================================+ | 0 | Simple C509 Certification Request Template | +-------+-----------------------------------------------------------+ Figure 9: C509 Certification Request Templates Types 8.6. C509 RDN Attributes Registry IANA has created a new registry titled "C509 RDN Attributes" in the new registry group "CBOR Encoded X.509 (C509)". The fields of the registry are Value, Name, Identifiers, OID, DER, Comments and Reference, where Value is a non-negative integer, and the other columns are text strings. Name and Identifiers are informal descriptions. The fields Name, OID, and DER are mandatory. For RDN Attributes specified only for CBOR encoded certificates where no OID is defined, the OID and DER fields are marked "N/A". If there is an OID defined, the OID is given in dotted decimal representation, and the DER column contains the hex string of the DER-encoded OID [X.690]. If it is not expected to be understood from the other information (e.g. the OID), then the Comments field must contain a reference to where the RDN Attribute is described. For values in the interval [0, 23] the registration procedure is "IETF Review with Expert Review". Values ≥ 32768 are reserved for Private Use. For all other values the registration procedure is "Expert Review". The initial contents of the registry are: +-------+-----------------------------------------------------------+ | Value | RDN Attribute | +=======+===========================================================+ | 0 | Name: Email Address | | | Identifiers: emailAddress, e-mailAddress | | | OID: 1.2.840.113549.1.9.1 | | | DER: 06 09 2A 86 48 86 F7 0D 01 09 01 | | | Comments: RFC 2985 | +-------+-----------------------------------------------------------+ | 1 | Name: Common Name | | | Identifiers: commonName, cn | | | OID: 2.5.4.3 | | | DER: 06 03 55 04 03 | | | Comments: X.520 | +-------+-----------------------------------------------------------+ | 2 | Name: Surname | | | Identifiers: surname, sn | Preuß Mattsson, et al. Expires 12 November 2026 [Page 36] Internet-Draft C509 Certificates May 2026 | | OID: 2.5.4.4 | | | DER: 06 03 55 04 04 | | | Comments: X.520 | +-------+-----------------------------------------------------------+ | 3 | Name: Serial Number | | | Identifiers: serialNumber | | | OID: 2.5.4.5 | | | DER: 06 03 55 04 05 | | | Comments: X.520 | +-------+-----------------------------------------------------------+ | 4 | Name: Country | | | Identifiers: countryName, c | | | OID: 2.5.4.6 | | | DER: 06 03 55 04 06 | | | Comments: X.520 | +-------+-----------------------------------------------------------+ | 5 | Name: Locality | | | Identifiers: localityName, locality, l | | | OID: 2.5.4.7 | | | DER: 06 03 55 04 07 | | | Comments: X.520 | +-------+-----------------------------------------------------------+ | 6 | Name: State or Province | | | Identifiers: stateOrProvinceName, st | | | OID: 2.5.4.8 | | | DER: 06 03 55 04 08 | | | Comments: X.520 | +-------+-----------------------------------------------------------+ | 7 | Name: Street Address | | | Identifiers: streetAddress, street | | | OID: 2.5.4.9 | | | DER: 06 03 55 04 09 | | | Comments: X.520 | +-------+-----------------------------------------------------------+ | 8 | Name: Organization | | | Identifiers: organizationName, o | | | OID: 2.5.4.10 | | | DER: 06 03 55 04 0A | | | Comments: X.520 | +-------+-----------------------------------------------------------+ | 9 | Name: Organizational Unit | | | Identifiers: organizationalUnitName, ou | | | OID: 2.5.4.11 | | | DER: 06 03 55 04 0B | | | Comments: X.520 | +-------+-----------------------------------------------------------+ | 10 | Name: Title | | | Identifiers: title | Preuß Mattsson, et al. Expires 12 November 2026 [Page 37] Internet-Draft C509 Certificates May 2026 | | OID: 2.5.4.12 | | | DER: 06 03 55 04 0C | | | Comments: X.520 | +-------+-----------------------------------------------------------+ | 11 | Name: Business Category | | | Identifiers: businessCategory | | | OID: 2.5.4.15 | | | DER: 06 03 55 04 0F | | | Comments: X.520 | +-------+-----------------------------------------------------------+ | 12 | Name: Postal Code | | | Identifiers: postalCode | | | OID: 2.5.4.17 | | | DER: 06 03 55 04 11 | | | Comments: X.520 | +-------+-----------------------------------------------------------+ | 13 | Name: Given Name | | | Identifiers: givenName | | | OID: 2.5.4.42 | | | DER: 06 03 55 04 2A | | | Comments: X.520 | +-------+-----------------------------------------------------------+ | 14 | Name: Initials | | | Identifiers: initials | | | OID: 2.5.4.43 | | | DER: 06 03 55 04 2B | | | Comments: X.520 | +-------+-----------------------------------------------------------+ | 15 | Name: Generation Qualifier | | | Identifiers: generationQualifier | | | OID: 2.5.4.44 | | | DER: 06 03 55 04 2C | | | Comments: X.520 | +-------+-----------------------------------------------------------+ | 16 | Name: DN Qualifier | | | Identifiers: dnQualifier | | | OID: 2.5.4.46 | | | DER: 06 03 55 04 2E | | | Comments: X.520 | +-------+-----------------------------------------------------------+ | 17 | Name: Pseudonym | | | Identifiers: pseudonym | | | OID: 2.5.4.65 | | | DER: 06 03 55 04 41 | | | Comments: X.520 | +-------+-----------------------------------------------------------+ | 18 | Name: Organization Identifier | | | Identifiers: organizationIdentifier | Preuß Mattsson, et al. Expires 12 November 2026 [Page 38] Internet-Draft C509 Certificates May 2026 | | OID: 2.5.4.97 | | | DER: 06 03 55 04 61 | | | Comments: X.520 | +-------+-----------------------------------------------------------+ | 19 | Name: Jurisdiction Locality Name | | | Identifiers: jurisdictionLocalityName | | | OID: 1.3.6.1.4.1.311.60.2.1.1 | | | DER: 06 0B 2B 06 01 04 01 82 37 3C 02 01 01 | | | Comments: Proprietary Microsoft Attribute | +-------+-----------------------------------------------------------+ | 20 | Name: Jurisdiction State or Province | | | Identifiers: jurisdictionStateOrProvinceName | | | OID: 1.3.6.1.4.1.311.60.2.1.2 | | | DER: 06 0B 2B 06 01 04 01 82 37 3C 02 01 02 | | | Comments: Proprietary Microsoft Attribute | +-------+-----------------------------------------------------------+ | 21 | Name: Jurisdiction Country Name | | | Identifiers: jurisdictionCountryName | | | OID: 1.3.6.1.4.1.311.60.2.1.3 | | | DER: 06 0B 2B 06 01 04 01 82 37 3C 02 01 03 | | | Comments: Proprietary Microsoft Attribute | +-------+-----------------------------------------------------------+ | 22 | Name: Domain Component | | | Identifiers: domainComponent, dc | | | OID: 0.9.2342.19200300.100.1.25 | | | DER: 06 0A 09 92 26 89 93 F2 2C 64 01 19 | | | Comments: RFC 4524 | +-------+-----------------------------------------------------------+ | 25 | Name: Name | | | Identifiers: name | | | OID: 2.5.4.41 | | | DER: 06 03 55 04 29 | | | Comments: X.520 | +-------+-----------------------------------------------------------+ | 26 | Name: Telephone Number | | | Identifiers: telephoneNumber | | | OID: 2.5.4.20 | | | DER: 06 03 55 04 14 | | | Comments: X.520 | +-------+-----------------------------------------------------------+ | 27 | Name: Directory Management Domain Name | | | Identifiers: dmdName | | | OID: 2.5.4.54 | | | DER: 06 03 55 04 36 | | | Comments: X.520 | +-------+-----------------------------------------------------------+ | 28 | Name: userid | | | Identifiers: uid | Preuß Mattsson, et al. Expires 12 November 2026 [Page 39] Internet-Draft C509 Certificates May 2026 | | OID: 0.9.2342.19200300.100.1.1 | | | DER: 06 0A 09 92 26 89 93 F2 2C 64 01 01 | | | Comments: RFC 4524 | +-------+-----------------------------------------------------------+ | 29 | Name: Unstructured Name | | | Identifiers: unstructuredName | | | OID: 1.2.840.113549.1.9.2 | | | DER: 06 09 2A 86 48 86 F7 0D 01 09 02 | | | Comments: RFC 2985 | +-------+-----------------------------------------------------------+ | 30 | Name: Unstructured Address | | | Identifiers: unstructuredAddress | | | OID: 1.2.840.113549.1.9.8 | | | DER: 06 0A 2A 86 48 86 F7 0D 01 09 08 | | | Comments: RFC 2985 | +-------+-----------------------------------------------------------+ Figure 10: C509 RDN Attributes 8.7. C509 CR Attributes Registry IANA has created a new registry titled "C509 CR Attributes" under the registry group "CBOR Encoded X.509 (C509)". The fields of the registry are Value, Name, Identifiers, OID, DER, Comments, attributeValue, and Reference, where Value is an integer, and the other columns are text strings. Name and Identifiers are informal descriptions. The fields Name, OID, and DER are mandatory. For CR Attributes specified only for CBOR encoded certificates where no OID is defined, the OID and DER fields are marked "N/A". If OID is present, the OID is given in dotted decimal representation, and the DER column contains the hex string of the DER-encoded OID [X.690]. If it is not expected to be understood from the other information (e.g. the OID), then the Comments field must contain a reference to where the CR Attribute is described. For values in the interval [-24, 23] the registration procedure is "IETF Review with Expert Review". Values ≥ 32768 are reserved for Private Use. For all other values the registration procedure is "Expert Review". The initial contents of the registry are: Preuß Mattsson, et al. Expires 12 November 2026 [Page 40] Internet-Draft C509 Certificates May 2026 +-------+-----------------------------------------------------------+ | Value | CR Attribute | +=======+===========================================================+ | 0 | Name: Extension Request | | | Identifiers: extensionRequest | | | OID: 1.2.840.113549.1.9.14 | | | DER: 06 09 2A 86 48 86 F7 0D 01 09 0E | | | Comments: RFC 2985 | | | attributeValue: Extensions | +-------+-----------------------------------------------------------+ | 1 | Name: Challenge Password | | | Identifiers: challengePassword | | | OID: 1.2.840.113549.1.9.7 | | | DER: 06 09 2A 86 48 86 F7 0D 01 09 07 | | | Comments: RFC 2985 | | | attributeValue: ChallengePassword | +-------+-----------------------------------------------------------+ | 2 | Name: Private Key Possession Statement | | | Identifiers: privateKeyPossessionStatement | | | OID: 1.3.6.1.4.1.22112.2.1 | | | DER: 06 0A 2B 06 01 04 01 81 AC 60 02 01 | | | Comments: RFC 9883 | | | attributeValue: PrivateKeyPossessionStatement | +-------+-----------------------------------------------------------+ Figure 11: C509 CRAttributes 8.8. C509 Extensions Registry IANA has created a new registry titled "C509 Extensions" under the new registry group "CBOR Encoded X.509 (C509)". The fields of the registry are Value, Name, Identifiers, OID, DER, Comments, extensionValue, and Reference, where Value is a positive integer, and the other columns are text strings. The fields Name, OID, DER, and extensionValue are mandatory. For all other values the registration procedure is "Expert Review". For Extensions specified only for CBOR encoded certificates where no OID is defined, the OID and DER fields are marked "N/A". If it is not expected to be understood from the other information (e.g. the OID), then the Comments field must contain a reference to where the Extension is described. For values in the interval [1, 23] the registration procedure is "IETF Review with Expert Review". Values ≥ 32768 are reserved for Private Use. The initial contents of the registry are: Preuß Mattsson, et al. Expires 12 November 2026 [Page 41] Internet-Draft C509 Certificates May 2026 +-------+-----------------------------------------------------------+ | Value | Extension | +=======+===========================================================+ | 1 | Name: Subject Key Identifier | | | Identifiers: subjectKeyIdentifier | | | OID: 2.5.29.14 | | | DER: 06 03 55 1D 0E | | | Comments: RFC 5280 | | | extensionValue: SubjectKeyIdentifier | +-------+-----------------------------------------------------------+ | 2 | Name: Key Usage | | | Identifiers: keyUsage | | | OID: 2.5.29.15 | | | DER: 06 03 55 1D 0F | | | Comments: RFC 5280 | | | extensionValue: KeyUsage | +-------+-----------------------------------------------------------+ | 3 | Name: Subject Alternative Name | | | Identifiers: subjectAltName | | | OID: 2.5.29.17 | | | DER: 06 03 55 1D 11 | | | Comments: RFC 5280 | | | extensionValue: SubjectAltName | +-------+-----------------------------------------------------------+ | 4 | Name: Basic Constraints | | | Identifiers: basicConstraints | | | OID: 2.5.29.19 | | | DER: 06 03 55 1D 13 | | | Comments: RFC 5280 | | | extensionValue: BasicConstraints | +-------+-----------------------------------------------------------+ | 5 | Name: CRL Distribution Points | | | Identifiers: cRLDistributionPoints | | | OID: 2.5.29.31 | | | DER: 06 03 55 1D 1F | | | Comments: RFC 5280 | | | extensionValue: CRLDistributionPoints | +-------+-----------------------------------------------------------+ | 6 | Name: Certificate Policies | | | Identifiers: certificatePolicies | | | OID: 2.5.29.32 | | | DER: 06 03 55 1D 20 | | | Comments: RFC 5280 | | | extensionValue: CertificatePolicies | +-------+-----------------------------------------------------------+ | 7 | Name: Authority Key Identifier | | | Identifiers: authorityKeyIdentifier | | | OID: 2.5.29.35 | Preuß Mattsson, et al. Expires 12 November 2026 [Page 42] Internet-Draft C509 Certificates May 2026 | | DER: 06 03 55 1D 23 | | | Comments: RFC 5280 | | | extensionValue: AuthorityKeyIdentifier | +-------+-----------------------------------------------------------+ | 8 | Name: Extended Key Usage | | | Identifiers: extKeyUsage | | | OID: 2.5.29.37 | | | DER: 06 03 55 1D 25 | | | Comments: RFC 5280 | | | extensionValue: ExtKeyUsageSyntax | +-------+-----------------------------------------------------------+ | 9 | Name: Authority Information Access | | | Identifiers: authorityInfoAccess | | | OID: 1.3.6.1.5.5.7.1.1 | | | DER: 06 08 2B 06 01 05 05 07 01 01 | | | Comments: RFC 5280 | | | extensionValue: AuthorityInfoAccessSyntax | +-------+-----------------------------------------------------------+ | 24 | Name: Subject Directory Attributes | | | Identifiers: subjectDirectoryAttributes | | | OID: 2.5.29.9 | | | DER: 06 03 55 1D 09 | | | Comments: RFC 5280 | | | extensionValue: SubjectDirectoryAttributes | +-------+-----------------------------------------------------------+ | 25 | Name: Issuer Alternative Name | | | Identifiers: issuerAltName | | | OID: 2.5.29.18 | | | DER: 06 03 55 1D 12 | | | Comments: RFC 5280 | | | extensionValue: IssuerAltName | +-------+-----------------------------------------------------------+ | 26 | Name: Name Constraints | | | Identifiers: nameConstraints | | | OID: 2.5.29.30 | | | DER: 06 03 55 1D 1E | | | Comments: RFC 9549 | | | extensionValue: NameConstraints | +-------+-----------------------------------------------------------+ | 27 | Name: Policy Mappings | | | Identifiers: policyMappings | | | OID: 2.5.29.33 | | | DER: 06 03 55 1D 21 | | | Comments: RFC 5280 | | | extensionValue: PolicyMappings | +-------+-----------------------------------------------------------+ | 28 | Name: Policy Constraints | | | Identifiers: policyConstraints | Preuß Mattsson, et al. Expires 12 November 2026 [Page 43] Internet-Draft C509 Certificates May 2026 | | OID: 2.5.29.36 | | | DER: 06 03 55 1D 24 | | | Comments: RFC 5280 | | | extensionValue: PolicyConstraints | +-------+-----------------------------------------------------------+ | 29 | Name: Freshest CRL | | | Identifiers: freshestCRL | | | OID: 2.5.29.46 | | | DER: 06 03 55 1D 2E | | | Comments: RFC 5280 | | | extensionValue: FreshestCRL | +-------+-----------------------------------------------------------+ | 30 | Name: Inhibit anyPolicy | | | Identifiers: inhibitAnyPolicy | | | OID: 2.5.29.54 | | | DER: 06 03 55 1D 36 | | | Comments: RFC 5280 | | | extensionValue: InhibitAnyPolicy | +-------+-----------------------------------------------------------+ | 31 | Name: Subject Information Access | | | Identifiers: subjectInfoAccess | | | OID: 1.3.6.1.5.5.7.1.11 | | | DER: 06 08 2B 06 01 05 05 07 01 0B | | | Comments: RFC 5280 | | | extensionValue: SubjectInfoAccessSyntax | +-------+-----------------------------------------------------------+ | 32 | Name: IPAddrBlocks | | | Identifiers: id-pe-ipAddrBlocks | | | OID: 1.3.6.1.5.5.7.1.7 | | | DER: 06 08 2B 06 01 05 05 07 01 07 | | | Comments: RFC 3779 | | | extensionValue: IPAddrBlocks | +-------+-----------------------------------------------------------+ | 33 | Name: AS Identifiers | | | Identifiers: id-pe-autonomousSysIds | | | OID: 1.3.6.1.5.5.7.1.8 | | | DER: 06 08 2B 06 01 05 05 07 01 08 | | | Comments: RFC 3779 | | | extensionValue: ASIdentifiers | +-------+-----------------------------------------------------------+ | 34 | Name: IPAddrBlocks v2 | | | Identifiers: id-pe-ipAddrBlocks-v2 | | | OID: 1.3.6.1.5.5.7.1.28 | | | DER: 06 08 2B 06 01 05 05 07 01 1C | | | Comments: RFC 8360 | | | extensionValue: IPAddrBlocks | +-------+-----------------------------------------------------------+ | 35 | Name: AS Identifiers v2 | Preuß Mattsson, et al. Expires 12 November 2026 [Page 44] Internet-Draft C509 Certificates May 2026 | | Identifiers: id-pe-autonomousSysIds-v2 | | | OID: 1.3.6.1.5.5.7.1.29 | | | DER: 06 08 2B 06 01 05 05 07 01 1D | | | Comments: RFC 8360 | | | extensionValue: ASIdentifiers | +-------+-----------------------------------------------------------+ | 36 | Name: OCSP No Check | | | Identifiers: id-pkix-ocsp-nocheck | | | OID: 1.3.6.1.5.5.7.48.1.5 | | | DER: 06 09 2B 06 01 05 05 07 30 01 05 | | | Comments: RFC 6960 | | | extensionValue: null | +-------+-----------------------------------------------------------+ | 38 | Name: TLS Features | | | Identifiers: id-pe-tlsfeature | | | OID: 1.3.6.1.5.5.7.1.24 | | | DER: 06 08 2B 06 01 05 05 07 01 18 | | | Comments: RFC 7633 | | | extensionValue: TLSFeatures | +-------+-----------------------------------------------------------+ Figure 12: C509 Extensions 8.9. C509 Certificate Policies Registry IANA has created a new registry titled "C509 Certificate Policies" under the registry group "CBOR Encoded X.509 (C509)". The fields of the registry are Value, Name, Identifiers, OID, DER, Comments, and Reference, where Value is an integer, and the other columns are text strings. The fields Name, OID, and DER are mandatory. For all other values the registration procedure is "Expert Review". For Certificate Policies specified only for CBOR encoded certificates where no OID is defined, the OID and DER fields are marked "N/A". If it is not expected to be understood from the other information (e.g. the OID), then the Comments field must contain a reference to where the Certificate Policy is described. For values in the interval [-24, 23] the registration procedure is "IETF Review with Expert Review". Values ≥ 32768 are reserved for Private Use. The initial contents of the registry are: +-------+-----------------------------------------------------------+ | Value | Certificate Policy | +=======+===========================================================+ | 0 | Name: Any Policy | | | Identifiers: anyPolicy | | | OID: 2.5.29.32.0 | | | DER: 06 04 55 1D 20 00 | Preuß Mattsson, et al. Expires 12 November 2026 [Page 45] Internet-Draft C509 Certificates May 2026 | | Comments: RFC 5280 | +-------+-----------------------------------------------------------+ | 1 | Name: Domain Validation (DV) | | | Identifiers: domain-validated | | | OID: 2.23.140.1.2.1 | | | DER: 06 06 67 81 0C 01 02 01 | | | Comments: CA/Browser Forum | +-------+-----------------------------------------------------------+ | 2 | Name: Organization Validation (OV) | | | Identifiers: organization-validated | | | OID: 2.23.140.1.2.2 | | | DER: 06 06 67 81 0C 01 02 02 | | | Comments: CA/Browser Forum | +-------+-----------------------------------------------------------+ | 3 | Name: Individual Validation (IV) | | | Identifiers: individual-validated | | | OID: 2.23.140.1.2.3 | | | DER: 06 06 67 81 0C 01 02 03 | | | Comments: CA/Browser Forum | +-------+-----------------------------------------------------------+ | 4 | Name: Extended Validation (EV) | | | Identifiers: ev-guidelines | | | OID: 2.23.140.1.1 | | | DER: 06 05 67 81 0C 01 01 | | | Comments: CA/Browser Forum | +-------+-----------------------------------------------------------+ | 7 | Name: Resource PKI (RPKI) | | | Identifiers: id-cp-ipAddr-asNumber | | | OID: 1.3.6.1.5.5.7.14.2 | | | DER: 06 08 2B 06 01 05 05 07 0E 02 | | | Comments: RFC 3779 | +-------+-----------------------------------------------------------+ | 8 | Name: Resource PKI (RPKI) (Alternative) | | | Identifiers: id-cp-ipAddr-asNumber-v2 | | | OID: 1.3.6.1.5.5.7.14.3 | | | DER: 06 08 2B 06 01 05 05 07 0E 03 | | | Comments: RFC 8360 | +-------+-----------------------------------------------------------+ | 24 | Name: Remote SIM Provisioning Role | | | Certificate Issuer | | | Identifiers: id-rspRole-ci | | | OID: 2.23.146.1.2.1.0 | | | DER: 06 07 67 81 12 01 02 01 00 | | | Comments: GSMA SGP.22 | +-------+-----------------------------------------------------------+ | 25 | Name: Remote SIM Provisioning Role | | | eUICC v2 | | | Identifiers: id-rspRole-euicc-v2 | Preuß Mattsson, et al. Expires 12 November 2026 [Page 46] Internet-Draft C509 Certificates May 2026 | | OID: 2.23.146.1.2.1.1 | | | DER: 06 07 67 81 12 01 02 01 01 | | | Comments: GSMA SGP.22 | +-------+-----------------------------------------------------------+ | 26 | Name: Remote SIM Provisioning Role | | | eUICC | | | Identifiers: id-rspRole-euicc | | | OID: 2.23.146.1.2.1.0.0.0.0.0 | | | DER: 06 0B 67 81 12 01 02 01 00 00 00 00 00 | | | Comments: GSMA SGP.22 | +-------+-----------------------------------------------------------+ | 27 | Name: Remote SIM Provisioning Role | | | eUICC Manufacturer v2 | | | Identifiers: id-rspRole-eum-v2 | | | OID: 2.23.146.1.2.1.2 | | | DER: 06 07 67 81 12 01 02 01 02 | | | Comments: GSMA SGP.22 | +-------+-----------------------------------------------------------+ | 28 | Name: Remote SIM Provisioning Role | | | eUICC Manufacturer | | | Identifiers: id-rspRole-eum | | | OID: 2.23.146.1.2.1.0.0.0 | | | DER: 06 09 67 81 12 01 02 01 00 00 00 | | | Comments: GSMA SGP.22 | +-------+-----------------------------------------------------------+ | 29 | Name: Remote SIM Provisioning Role | | | SM-DP+ TLS v2 | | | Identifiers: id-rspRole-dp-tls-v2 | | | OID: 2.23.146.1.2.1.3 | | | DER: 06 07 67 81 12 01 02 01 03 | | | Comments: GSMA SGP.22 | +-------+-----------------------------------------------------------+ | 30 | Name: Remote SIM Provisioning Role | | | SM-DP+ TLS | | | Identifiers: id-rspRole-dp-tls | | | OID: 2.23.146.1.2.1.0.0.1.0 | | | DER: 06 0A 67 81 12 01 02 01 00 00 01 00 | | | Comments: GSMA SGP.22 | +-------+-----------------------------------------------------------+ | 31 | Name: Remote SIM Provisioning Role | | | SM-DP+ Authentication v2 | | | Identifiers: id-rspRole-dp-auth-v2 | | | OID: 2.23.146.1.2.1.4 | | | DER: 06 07 67 81 12 01 02 01 04 | | | Comments: GSMA SGP.22 | +-------+-----------------------------------------------------------+ | 32 | Name: Remote SIM Provisioning Role | | | SM-DP+ Authentication | Preuß Mattsson, et al. Expires 12 November 2026 [Page 47] Internet-Draft C509 Certificates May 2026 | | Identifiers: id-rspRole-dp-auth | | | OID: 2.23.146.1.2.1.0.0.1.1 | | | DER: 06 0A 67 81 12 01 02 01 00 00 01 01 | | | Comments: GSMA SGP.22 | +-------+-----------------------------------------------------------+ | 33 | Name: Remote SIM Provisioning Role | | | SM-DP+ Profile Binding v2 | | | Identifiers: id-rspRole-dp-pb-v2 | | | OID: 2.23.146.1.2.1.5 | | | DER: 06 07 67 81 12 01 02 01 05 | | | Comments: GSMA SGP.22 | +-------+-----------------------------------------------------------+ | 34 | Name: Remote SIM Provisioning Role | | | SM-DP+ Profile Binding | | | Identifiers: id-rspRole-dp-pb | | | OID: 2.23.146.1.2.1.0.0.1.2 | | | DER: 06 0A 67 81 12 01 02 01 00 00 01 02 | | | Comments: GSMA SGP.22 | +-------+-----------------------------------------------------------+ | 35 | Name: Remote SIM Provisioning Role | | | SM-DS TLS v2 | | | Identifiers: id-rspRole-ds-tls-v2 | | | OID: 2.23.146.1.2.1.6 | | | DER: 06 07 67 81 12 01 02 01 06 | | | Comments: GSMA SGP.22 | +-------+-----------------------------------------------------------+ | 36 | Name: Remote SIM Provisioning Role | | | SM-DS TLS | | | Identifiers: id-rspRole-ds-tls | | | OID: 2.23.146.1.2.1.0.0.2.0 | | | DER: 06 0A 67 81 12 01 02 01 00 00 02 00 | | | Comments: GSMA SGP.22 | +-------+-----------------------------------------------------------+ | 37 | Name: Remote SIM Provisioning Role | | | SM-DS Authentication v2 | | | Identifiers: id-rspRole-ds-auth-v2 | | | OID: 2.23.146.1.2.1.7 | | | DER: 06 07 67 81 12 01 02 01 07 | | | Comments: GSMA SGP.22 | +-------+-----------------------------------------------------------+ | 38 | Name: Remote SIM Provisioning Role | | | SM-DS Authentication | | | Identifiers: id-rspRole-ds-auth | | | OID: 2.23.146.1.2.1.0.0.2.1 | | | DER: 06 0A 67 81 12 01 02 01 00 00 02 01 | | | Comments: GSMA SGP.22 | +-------+-----------------------------------------------------------+ Preuß Mattsson, et al. Expires 12 November 2026 [Page 48] Internet-Draft C509 Certificates May 2026 Figure 13: C509 Certificate Policies 8.10. C509 Policies Qualifiers Registry IANA has created a new registry titled "C509 Policies Qualifiers" under the registry group "CBOR Encoded X.509 (C509)". The fields of the registry are Value, Name, Identifiers, OID, DER, Comments, and Reference, where Value is an integer, and the other columns are text strings. The fields Name, OID, and DER are mandatory. If it is not expected to be understood from the other information (e.g. the OID), then the Comments field must contain a reference to where the Policy Qualifier is described. For values in the interval [-24, 23] the registration procedure is "IETF Review with Expert Review". Values ≥ 32768 are reserved for Private Use. For all other values the registration procedure is "Expert Review". The initial contents of the registry are: +-------+-----------------------------------------------------------+ | Value | Policy Qualifier | +=======+===========================================================+ | 1 | Name: Certification Practice Statement | | | Identifiers: id-qt-cps, cps | | | OID: 1.3.6.1.5.5.7.2.1 | | | DER: 06 08 2B 06 01 05 05 07 02 01 | | | Comments: RFC 5280 | +-------+-----------------------------------------------------------+ | 2 | Name: User Notice | | | Identifiers: id-qt-unotice, unotice | | | OID: 1.3.6.1.5.5.7.2.2 | | | DER: 06 08 2B 06 01 05 05 07 02 02 | | | Comments: RFC 5280 | +-------+-----------------------------------------------------------+ Figure 14: C509 Policies Qualifiers 8.11. C509 Information Access Registry IANA has created a new registry titled "C509 Information Access" under the registry group "CBOR Encoded X.509 (C509)". The fields of the registry are Value, Name, Identifiers, OID, DER, Comments, and Reference, where Value is an integer, and the other columns are text strings. The fields Name, OID, and DER are mandatory. If it is not expected to be understood from the other information (e.g. the OID), then the Comments field must contain a reference to where the Information Access is described. For values in the interval [-24, 23] the registration procedure is "IETF Review with Expert Review". For all other values the registration procedure is "Expert Review". Preuß Mattsson, et al. Expires 12 November 2026 [Page 49] Internet-Draft C509 Certificates May 2026 The initial contents of the registry are: +-------+-----------------------------------------------------------+ | Value | Information Access | +=======+===========================================================+ | 1 | Name: OCSP | | | Identifiers: id-ad-ocsp, id-pkix-ocsp | | | OID: 1.3.6.1.5.5.7.48.1 | | | DER: 06 08 2B 06 01 05 05 07 30 01 | | | Comments: RFC 5280 | +-------+-----------------------------------------------------------+ | 2 | Name: CA Issuers | | | Identifiers: id-ad-caIssuers, caIssuers | | | OID: 1.3.6.1.5.5.7.48.2 | | | DER: 06 08 2B 06 01 05 05 07 30 02 | | | Comments: RFC 5280 | +-------+-----------------------------------------------------------+ | 3 | Name: Time Stamping | | | Identifiers: id-ad-timeStamping, timeStamping | | | OID: 1.3.6.1.5.5.7.48.3 | | | DER: 06 08 2B 06 01 05 05 07 30 03 | | | Comments: RFC 3161 | +-------+-----------------------------------------------------------+ | 5 | Name: CA Repository | | | Identifiers: id-ad-caRepository | | | OID: 1.3.6.1.5.5.7.48.5 | | | DER: 06 08 2B 06 01 05 05 07 30 05 | | | Comments: RFC 5280 | +-------+-----------------------------------------------------------+ | 10 | Name: RPKI Manifest | | | Identifiers: id-ad-rpkiManifest | | | OID: 1.3.6.1.5.5.7.48.10 | | | DER: 06 08 2B 06 01 05 05 07 30 0A | | | Comments: RFC 6487 | +-------+-----------------------------------------------------------+ | 11 | Name: Signed Object | | | Identifiers: id-ad-signedObject | | | OID: 1.3.6.1.5.5.7.48.11 | | | DER: 06 08 2B 06 01 05 05 07 30 0B | | | Comments: RFC 6487 | +-------+-----------------------------------------------------------+ | 13 | Name: RPKI Notify | | | Identifiers: id-ad-rpkiNotify | | | OID: 1.3.6.1.5.5.7.48.13 | | | DER: 06 08 2B 06 01 05 05 07 30 0D | | | Comments: RFC 8182 | +-------+-----------------------------------------------------------+ Preuß Mattsson, et al. Expires 12 November 2026 [Page 50] Internet-Draft C509 Certificates May 2026 Figure 15: C509 Information Accesses 8.12. C509 Extended Key Usages Registry IANA has created a new registry titled "C509 Extended Key Usages" under the registry group "CBOR Encoded X.509 (C509)". The fields of the registry are Value, Name, Identifiers, OID, DER, Comments, and Reference, where Value is an integer, and the other columns are text strings. The fields Name, OID, and DER are mandatory. For Extended Key Usage specified only for CBOR encoded certificates where no OID is defined, the OID and DER fields are marked "N/A". If it is not expected to be understood from the other information (e.g. the OID), then the Comments field must contain a reference to where the Extended Key Usage is described. For values in the interval [-24, 23] the registration procedure is "IETF Review with Expert Review". Values ≥ 32768 are reserved for Private Use. For all other values the registration procedure is "Expert Review". The initial contents of the registry are: +-------+---------------------------------------------------------+ | Value | Extended Key Usage | +=======+=========================================================+ | 0 | Name: Any Extended Key Usage | | | Identifiers: anyExtendedKeyUsage | | | OID: 2.5.29.37.0 | | | DER: 06 04 55 1D 25 00 | | | Comments: RFC 5280 | +-------+---------------------------------------------------------+ | 1 | Name: TLS Server authentication | | | Identifiers: id-kp-serverAuth | | | OID: 1.3.6.1.5.5.7.3.1 | | | DER: 06 08 2B 06 01 05 05 07 03 01 | | | Comments: RFC 5280 | +-------+---------------------------------------------------------+ | 2 | Name: TLS Client Authentication | | | Identifiers: id-kp-clientAuth | | | OID: 1.3.6.1.5.5.7.3.2 | | | DER: 06 08 2B 06 01 05 05 07 03 02 | | | Comments: RFC 5280 | +-------+---------------------------------------------------------+ | 3 | Name: Code Signing | | | Identifiers: id-kp-codeSigning | | | OID: 1.3.6.1.5.5.7.3.3 | | | DER: 06 08 2B 06 01 05 05 07 03 03 | | | Comments: RFC 5280 | +-------+---------------------------------------------------------+ | 4 | Name: Email protection (S/MIME) | Preuß Mattsson, et al. Expires 12 November 2026 [Page 51] Internet-Draft C509 Certificates May 2026 | | Identifiers: id-kp-emailProtection | | | OID: 1.3.6.1.5.5.7.3.4 | | | DER: 06 08 2B 06 01 05 05 07 03 04 | | | Comments: RFC 5280 | +-------+---------------------------------------------------------+ | 8 | Name: Time Stamping | | | Identifiers: id-kp-timeStamping, timestamping | | | OID: 1.3.6.1.5.5.7.3.8 | | | DER: 06 08 2B 06 01 05 05 07 03 08 | | | Comments: RFC 3161 | +-------+---------------------------------------------------------+ | 9 | Name: OCSP Signing | | | Identifiers: id-kp-OCSPSigning | | | OID: 1.3.6.1.5.5.7.3.9 | | | DER: 06 08 2B 06 01 05 05 07 03 09 | | | Comments: RFC 5280 | +-------+---------------------------------------------------------+ | 10 | Name: Kerberos PKINIT Client Auth | | | Identifiers: id-pkinit-KPClientAuth | | | OID: 1.3.6.1.5.2.3.4 | | | DER: 06 07 2B 06 01 05 02 03 04 | | | Comments: RFC 4556 | +-------+---------------------------------------------------------+ | 11 | Name: Kerberos PKINIT KDC | | | Identifiers: id-pkinit-KPKdc | | | OID: 1.3.6.1.5.2.3.5 | | | DER: 06 07 2B 06 01 05 02 03 05 | | | Comments: RFC 4556 | +-------+---------------------------------------------------------+ | 12 | Name: SSH Client | | | Identifiers: id-kp-secureShellClient | | | OID: 1.3.6.1.5.5.7.3.21 | | | DER: 06 08 2B 06 01 05 05 07 03 15 | | | Comments: RFC 6187 | +-------+---------------------------------------------------------+ | 13 | Name: SSH Server | | | Identifiers: id-kp-secureShellServer | | | OID: 1.3.6.1.5.5.7.3.22 | | | DER: 06 08 2B 06 01 05 05 07 03 16 | | | Comments: RFC 6187 | +-------+---------------------------------------------------------+ | 14 | Name: Bundle Security | | | Identifiers: id-kp-bundleSecurity | | | OID: 1.3.6.1.5.5.7.3.35 | | | DER: 06 08 2B 06 01 05 05 07 03 23 | | | Comments: RFC 9174 | +-------+---------------------------------------------------------+ | 15 | Name: CMC Certification Authority | Preuß Mattsson, et al. Expires 12 November 2026 [Page 52] Internet-Draft C509 Certificates May 2026 | | Identifiers: id-kp-cmcCA | | | OID: 1.3.6.1.5.5.7.3.27 | | | DER: 06 08 2B 06 01 05 05 07 03 1B | | | Comments: RFC 6402 | +-------+---------------------------------------------------------+ | 16 | Name: CMC Registration Authority | | | Identifiers: id-kp-cmcRA | | | OID: 1.3.6.1.5.5.7.3.28 | | | DER: 06 08 2B 06 01 05 05 07 03 1C | | | Comments: RFC 6402 | +-------+---------------------------------------------------------+ | 17 | Name: CMC Archive Server | | | Identifiers: id-kp-cmcArchive | | | OID: 1.3.6.1.5.5.7.3.29 | | | DER: 06 08 2B 06 01 05 05 07 03 1D | | | Comments: RFC 6402 | +-------+---------------------------------------------------------+ | 18 | Name: CMC Key Generation Authority | | | Identifiers: id-kp-cmKGA | | | OID: 1.3.6.1.5.5.7.3.32 | | | DER: 06 08 2B 06 01 05 05 07 03 20 | | | Comments: RFC 9480 | +-------+---------------------------------------------------------+ | 20 | Name: Wi-SUN FAN Device | | | Identifiers: id-kp-wisun-fan-device | | | OID: 1.3.6.1.4.1.45605.1 | | | DER: 06 09 2B 06 01 04 01 82 E4 25 01 | | | Comments: | +-------+---------------------------------------------------------+ Figure 16: C509 Extended Key Usages 8.13. C509 General Names Registry IANA has created a new registry titled "C509 General Names" under the registry group "CBOR Encoded X.509 (C509)". The fields of the registry are Value, Name, Comments, GeneralNameValue, and Reference, where Value is an integer, and the other columns are text strings. The fields Name and GeneralNameValue are mandatory. If it is not expected to be understood from the other information (e.g. the OID), then the Comments field must contain a reference to where the General Name is described. For values in the interval [-24, 23] the registration procedure is "IETF Review with Expert Review". For all other values the registration procedure is "Expert Review". The initial contents of the registry are: Preuß Mattsson, et al. Expires 12 November 2026 [Page 53] Internet-Draft C509 Certificates May 2026 +-------+-----------------------------------------------------------+ | Value | General Name | +=======+===========================================================+ | -3 | Name: otherName with MACAddress | | | Comments: TBD92(Use RFC I-D-lamps-macaddress-on) | | | id-on-MACAddress | | | (1.3.6.1.5.5.7.8.12) | | | 06 08 2B 06 01 05 05 07 08 0C | | | GeneralNameValue: bytes | +-------+-----------------------------------------------------------+ | -2 | Name: otherName with SmtpUTF8Mailbox | | | Comments: RFC 9598 | | | id-on-SmtpUTF8Mailbox | | | (1.3.6.1.5.5.7.8.9) | | | 06 08 2B 06 01 05 05 07 08 09 | | | GeneralNameValue: text | +-------+-----------------------------------------------------------+ | -1 | Name: otherName with hardwareModuleName | | | Comments: RFC 4108 | | | id-on-hardwareModuleName | | | (1.3.6.1.5.5.7.8.4) | | | 06 08 2B 06 01 05 05 07 08 04 | | | GeneralNameValue: [ ~oid, bytes ] | +-------+-----------------------------------------------------------+ | 0 | Name: otherName | | | Comments: RFC 5280 | | | GeneralNameValue: [ ~oid, bytes ] | +-------+-----------------------------------------------------------+ | 1 | Name: rfc822Name | | | Comments: RFC 5280 | | | GeneralNameValue: text | +-------+-----------------------------------------------------------+ | 2 | Name: dNSName | | | Comments: RFC 5280 | | | GeneralNameValue: text | +-------+-----------------------------------------------------------+ | 4 | Name: directoryName | | | Comments: RFC 5280 | | | GeneralNameValue: Name | +-------+-----------------------------------------------------------+ | 6 | Name: uniformResourceIdentifier | | | Comments: RFC 5280 | | | GeneralNameValue: text | +-------+-----------------------------------------------------------+ | 7 | Name: iPAddress | | | Comments: RFC 5280 | | | GeneralNameValue: bytes | +-------+-----------------------------------------------------------+ Preuß Mattsson, et al. Expires 12 November 2026 [Page 54] Internet-Draft C509 Certificates May 2026 | 8 | Name: registeredID | | | Comments RFC 5280 | | | GeneralNameValue: ~oid | +-------+-----------------------------------------------------------+ Figure 17: C509 General Names 8.14. C509 Signature Algorithms Registry IANA has created a new registry titled "C509 Signature Algorithms" under the registry group "CBOR Encoded X.509 (C509)". The registry includes both signature algorithms and non-signature proof-of- possession algorithms. The fields of the registry are Value, Name, Identifiers, OID, Parameters, DER, Comments, and Reference, where Value is an integer, and the other columns are text strings. The fields Name, OID, Parameters, and DER are mandatory. Alignment with the value of public key algorithm must be considered, see instruction in Section 8.15. If it is not expected to be understood from the other information (e.g. the OID), then the Comments field must contain a reference to where the Signature Algorithm is described. For values in the interval [-24, 23] the registration procedure is "IETF Review with Expert Review". For all other values the registration procedure is "Expert Review". The initial contents of the registry are: +-------+-----------------------------------------------------------+ | Value | Signature Algorithm | +=======+===========================================================+ | -256 | Name: RSASSA-PKCS1-v1_5 with SHA-1 | | | Identifiers: sha1-with-rsa-signature, | | | sha1WithRSAEncryption, | | | sha-1WithRSAEncryption | | | OID: 1.2.840.113549.1.1.5 | | | Parameters: NULL | | | DER: 30 0D 06 09 2A 86 48 86 F7 0D 01 01 05 05 00 | | | Comments: | +-------+-----------------------------------------------------------+ | -255 | Name: ECDSA with SHA-1 | | | Identifiers: ecdsa-with-SHA1 | | | OID: 1.2.840.10045.4.1 | | | Parameters: Absent | | | DER: 30 09 06 07 2A 86 48 CE 3D 04 01 | | | Comments: See Section 3.2.2. | +-------+-----------------------------------------------------------+ | 0 | Name: ECDSA with SHA-256 | | | Identifiers: ecdsa-with-SHA256 | | | OID: 1.2.840.10045.4.3.2 | | | Parameters: Absent | Preuß Mattsson, et al. Expires 12 November 2026 [Page 55] Internet-Draft C509 Certificates May 2026 | | DER: 30 0A 06 08 2A 86 48 CE 3D 04 03 02 | | | Comments: See Section 3.2.2. | +-------+-----------------------------------------------------------+ | 1 | Name: ECDSA with SHA-384 | | | Identifiers: ecdsa-with-SHA384 | | | OID: 1.2.840.10045.4.3.3 | | | Parameters: Absent | | | DER: 30 0A 06 08 2A 86 48 CE 3D 04 03 03 | | | Comments: See Section 3.2.2. | +-------+-----------------------------------------------------------+ | 2 | Name: ECDSA with SHA-512 | | | Identifiers: ecdsa-with-SHA512 | | | OID: 1.2.840.10045.4.3.4 | | | Parameters: Absent | | | DER: 30 0A 06 08 2A 86 48 CE 3D 04 03 04 | | | Comments: See Section 3.2.2. | +-------+-----------------------------------------------------------+ | 3 | Name: ECDSA with SHAKE128 | | | Identifiers: id-ecdsa-with-shake128 | | | OID: 1.3.6.1.5.5.7.6.32 | | | Parameters: Absent | | | DER: 30 0A 06 08 2B 06 01 05 05 07 06 20 | | | Comments: See Section 3.2.2. | +-------+-----------------------------------------------------------+ | 4 | Name: ECDSA with SHAKE256 | | | Identifiers: id-ecdsa-with-shake256 | | | OID: 1.3.6.1.5.5.7.6.33 | | | Parameters: Absent | | | DER: 30 0A 06 08 2B 06 01 05 05 07 06 21 | | | Comments: See Section 3.2.2. | +-------+-----------------------------------------------------------+ | 5 | Name: Unsigned | | | Identifiers: id-alg-unsigned | | | OID: 1.3.6.1.5.5.7.6.36 | | | Parameters: Absent | | | DER: 30 0A 06 08 2B 06 01 05 05 07 06 24 | | | Comments: bytes of size 0 | +-------+-----------------------------------------------------------+ | 8 | Name: SM2 with SM3 | | | Identifiers: sm2-with-sm3 | | | OID: 1.2.156.10197.1.501 | | | Parameters: Absent | | | DER: 30 0A 06 08 2A 81 1C CF 55 01 83 75 | | | Comments: See Section 3.2.2. | +-------+-----------------------------------------------------------+ | 12 | Name: Ed25519 | | | Identifiers: id-Ed25519, id-EdDSA25519 | | | OID: 1.3.101.112 | Preuß Mattsson, et al. Expires 12 November 2026 [Page 56] Internet-Draft C509 Certificates May 2026 | | Parameters: Absent | | | DER: 30 05 06 03 2B 65 70 | | | Comments: | +-------+-----------------------------------------------------------+ | 13 | Name: Ed448 | | | Identifiers: id-Ed448, id-EdDSA448 | | | OID: 1.3.101.113 | | | Parameters: Absent | | | DER: 30 05 06 03 2B 65 71 | | | Comments: | +-------+-----------------------------------------------------------+ | 14 | Name: PoP with SHA-256 and HMAC-SHA256 | | | Identifiers: sa-ecdhPop-sha256-hmac-sha256 | | | OID: 1.3.6.1.5.5.7.6.26 | | | Parameters: Absent | | | DER: 30 0A 06 08 2B 06 01 05 05 07 06 1A | | | Comments: Proof-of-possession algorithm, indexed with | | | KDF and MAC, see RFC 6955. Requires | | | recipient's public static Diffie-Hellman key | +-------+-----------------------------------------------------------+ | 15 | Name: PoP with SHA-384 and HMAC-SHA384 | | | Identifiers: sa-ecdhPop-sha384-hmac-sha384 | | | OID: 1.3.6.1.5.5.7.6.27 | | | Parameters: Absent | | | DER: 30 0A 06 08 2B 06 01 05 05 07 06 1B | | | Comments: Proof-of-possession algorithm, indexed with | | | KDF and MAC, see RFC 6955. Requires | | | recipient's public static Diffie-Hellman key | +-------+-----------------------------------------------------------+ | 16 | Name: PoP with SHA-512 and HMAC-SHA512 | | | Identifiers: sa-ecdhPop-sha512-hmac-sha512 | | | OID: 1.3.6.1.5.5.7.6.28 | | | Parameters: Absent | | | DER: 30 0A 06 08 2B 06 01 05 05 07 06 1C | | | Comments: Proof-of-possession algorithm, indexed with | | | KDF and MAC, see RFC 6955. Requires | | | recipient's public static Diffie-Hellman key | +-------+-----------------------------------------------------------+ | 23 | Name: RSASSA-PKCS1-v1_5 with SHA-256 | | | Identifiers: sha256WithRSAEncryption | | | OID: 1.2.840.113549.1.1.11 | | | Parameters: NULL | | | DER: 30 0B 06 09 2A 86 48 86 F7 0D 01 01 0B 05 00 | | | Comments: | +-------+-----------------------------------------------------------+ | 24 | Name: RSASSA-PKCS1-v1_5 with SHA-384 | | | Identifiers: sha384WithRSAEncryption | | | OID: 1.2.840.113549.1.1.12 | Preuß Mattsson, et al. Expires 12 November 2026 [Page 57] Internet-Draft C509 Certificates May 2026 | | Parameters: NULL | | | DER: 30 0B 06 09 2A 86 48 86 F7 0D 01 01 0C 05 00 | | | Comments: | +-------+-----------------------------------------------------------+ | 25 | Name: RSASSA-PKCS1-v1_5 with SHA-512 | | | Identifiers: sha512WithRSAEncryption | | | OID: 1.2.840.113549.1.1.13 | | | Parameters: NULL | | | DER: 30 0B 06 09 2A 86 48 86 F7 0D 01 01 0D 05 00 | | | Comments: | +-------+-----------------------------------------------------------+ | 26 | Name: RSASSA-PSS with SHA-256 | | | Identifiers: rsassa-pss, id-RSASSA-PSS | | | OID: 1.2.840.113549.1.1.10 | | | Parameters: SHA-256, MGF-1 with SHA-256, saltLength = 32 | | | DER: 30 41 06 09 2A 86 48 86 F7 0D 01 01 0A 30 34 | | | A0 0F 30 0D 06 09 60 86 48 01 65 03 04 02 01 | | | 05 00 A1 1C 30 1A 06 09 2A 86 48 86 F7 0D 01 | | | 01 08 30 0D 06 09 60 86 48 01 65 03 04 02 01 | | | 05 00 A2 03 02 01 20 | | | Comments: | +-------+-----------------------------------------------------------+ | 27 | Name: RSASSA-PSS with SHA-384 | | | Identifiers: rsassa-pss, id-RSASSA-PSS | | | OID: 1.2.840.113549.1.1.10 | | | Parameters: SHA-384, MGF-1 with SHA-384, saltLength = 48 | | | DER: 30 41 06 09 2A 86 48 86 F7 0D 01 01 0A 30 34 | | | A0 0F 30 0D 06 09 60 86 48 01 65 03 04 02 02 | | | 05 00 A1 1C 30 1A 06 09 2A 86 48 86 F7 0D 01 | | | 01 08 30 0D 06 09 60 86 48 01 65 03 04 02 02 | | | 05 00 A2 03 02 01 30 | | | Comments: | +-------+-----------------------------------------------------------+ | 28 | Name: RSASSA-PSS with SHA-512 | | | Identifiers: rsassa-pss, id-RSASSA-PSS | | | OID: 1.2.840.113549.1.1.10 | | | Parameters: SHA-512, MGF-1 with SHA-512, saltLength = 64 | | | DER: 30 41 06 09 2A 86 48 86 F7 0D 01 01 0A 30 34 | | | A0 0F 30 0D 06 09 60 86 48 01 65 03 04 02 03 | | | 05 00 A1 1C 30 1A 06 09 2A 86 48 86 F7 0D 01 | | | 01 08 30 0D 06 09 60 86 48 01 65 03 04 02 03 | | | 05 00 A2 03 02 01 40 | | | Comments: | +-------+-----------------------------------------------------------+ | 29 | Name: RSASSA-PSS with SHAKE128 | | | Identifiers: id-RSASSA-PSS-SHAKE128 | | | OID: 1.3.6.1.5.5.7.6.30 | | | Parameters: Absent | Preuß Mattsson, et al. Expires 12 November 2026 [Page 58] Internet-Draft C509 Certificates May 2026 | | DER: 30 0A 06 08 2B 06 01 05 05 07 06 1E | | | Comments: | +-------+-----------------------------------------------------------+ | 30 | Name: RSASSA-PSS with SHAKE256 | | | Identifiers: id-RSASSA-PSS-SHAKE256 | | | OID: 1.3.6.1.5.5.7.6.31 | | | Parameters: Absent | | | DER: 30 0A 06 08 2B 06 01 05 05 07 06 1F | | | Comments: | +-------+-----------------------------------------------------------+ Figure 18: C509 Signature Algorithms 8.15. C509 Public Key Algorithms Registry IANA has created a new registry titled "C509 Public Key Algorithms" under the registry group "CBOR Encoded X.509 (C509)". The fields of the registry are Value, Name, Identifiers, OID, Parameters, DER, Comments, and Reference, where Value is an integer, and the other columns are text strings. The fields Name, OID, Parameters, and DER are mandatory. If the public key can only be used with one signature algorithm and the OID of the public key algorithm is the same as the signature algorithm, then the value must be chosen equal to the value of signature algorithm, see Section 8.14. If it is not expected to be understood from the other information (e.g. the OID), then the Comments field must contain a reference to where the Public Key Algorithm is described. For values in the interval [-24, 23] the registration procedure is "IETF Review with Expert Review". For all other values the registration procedure is "Expert Review". The initial contents of the registry are: +-------+-----------------------------------------------------------+ | Value | Public Key Algorithm | +=======+===========================================================+ | 0 | Name: RSA | | | Identifiers: rsaEncryption | | | OID: 1.2.840.113549.1.1.1 | | | Parameters: NULL | | | DER: 30 0D 06 09 2A 86 48 86 F7 0D 01 01 01 05 00 | | | Comments: subjectPublicKey encoded as in Section 3.2.1 | +-------+-----------------------------------------------------------+ | 1 | Name: EC Public Key (Weierstrass) with secp256r1 | | | Identifiers: ecPublicKey, id-ecPublicKey | | | OID: 1.2.840.10045.2.1 | | | Parameters: namedCurve = secp256r1 (1.2.840.10045.3.1.7) | | | DER: 30 13 06 07 2A 86 48 CE 3D 02 01 06 08 2A 86 | | | 48 CE 3D 03 01 07 | | | Comments: subjectPublicKey encoded as in Section 3.2.1 | Preuß Mattsson, et al. Expires 12 November 2026 [Page 59] Internet-Draft C509 Certificates May 2026 | | Also known as P-256, ansip256r1, prime256v1 | +-------+-----------------------------------------------------------+ | 2 | Name: EC Public Key (Weierstrass) with secp384r1 | | | Identifiers: ecPublicKey, id-ecPublicKey | | | OID: 1.2.840.10045.2.1 | | | Parameters: namedCurve = secp384r1 (1.3.132.0.34) | | | DER: 30 10 06 07 2A 86 48 CE 3D 02 01 06 05 2B 81 | | | 04 00 22 | | | Comments: subjectPublicKey encoded as in Section 3.2.1 | | | Also known as P-384, ansip384r1 | +-------+-----------------------------------------------------------+ | 3 | Name: EC Public Key (Weierstrass) with secp521r1 | | | Identifiers: ecPublicKey, id-ecPublicKey | | | OID: 1.2.840.10045.2.1 | | | Parameters: namedCurve = secp521r1 (1.3.132.0.35) | | | DER: 30 10 06 07 2A 86 48 CE 3D 02 01 06 05 2B 81 | | | 04 00 23 | | | Comments: subjectPublicKey encoded as in Section 3.2.1 | | | Also known as P-521, ansip521r1 | +-------+-----------------------------------------------------------+ | 6 | Name: EC Public Key (Weierstrass) with | | | sm2p256v1 | | | Identifiers: ecPublicKey, id-ecPublicKey | | | OID: 1.2.840.10045.2.1 | | | Parameters: namedCurve = sm2p256v1 | | | (1.2.156.10197.1.301) | | | DER: 30 13 06 07 2A 86 48 CE 3D 02 01 06 08 2A 81 | | | 1C CF 55 01 82 2D | | | Comments: subjectPublicKey encoded as in Section 3.2.1 | +-------+-----------------------------------------------------------+ | 8 | Name: X25519 (Montgomery) | | | Identifiers: id-X25519 | | | OID: 1.3.101.110 | | | Parameters: Absent | | | DER: 30 05 06 03 2B 65 6E | | | Comments: | +-------+-----------------------------------------------------------+ | 9 | Name: X448 (Montgomery) | | | Identifiers: id-X448 | | | OID: 1.3.101.111 | | | Parameters: Absent | | | DER: 30 05 06 03 2B 65 6F | | | Comments: | +-------+-----------------------------------------------------------+ | 12 | Name: Ed25519 (Twisted Edwards) | | | Identifiers: id-Ed25519, id-EdDSA25519 | | | OID: 1.3.101.112 | | | Parameters: Absent | Preuß Mattsson, et al. Expires 12 November 2026 [Page 60] Internet-Draft C509 Certificates May 2026 | | DER: 30 05 06 03 2B 65 70 | | | Comments: | +-------+-----------------------------------------------------------+ | 13 | Name: Ed448 (Edwards) | | | Identifiers: id-Ed448, id-EdDSA448 | | | OID: 1.3.101.113 | | | Parameters: Absent | | | DER: 30 05 06 03 2B 65 71 | | | Comments: | +-------+-----------------------------------------------------------+ | 24 | Name: EC Public Key (Weierstrass) with | | | brainpoolP256r1 | | | Identifiers: ecPublicKey, id-ecPublicKey | | | OID: 1.2.840.10045.2.1 | | | Parameters: namedCurve = brainpoolP256r1 | | | (1.3.36.3.3.2.8.1.1.7) | | | DER: 30 14 06 07 2A 86 48 CE 3D 02 01 06 09 2B 24 | | | 03 03 02 08 01 01 07 | | | Comments: subjectPublicKey encoded as in Section 3.2.1 | +-------+-----------------------------------------------------------+ | 25 | Name: EC Public Key (Weierstrass) with | | | brainpoolP384r1 | | | Identifiers: ecPublicKey, id-ecPublicKey | | | OID: 1.2.840.10045.2.1 | | | Parameters: namedCurve = brainpoolP384r1 | | | (1.3.36.3.3.2.8.1.1.11) | | | DER: 30 14 06 07 2A 86 48 CE 3D 02 01 06 09 2B 24 | | | 03 03 02 08 01 01 0B | | | Comments: subjectPublicKey encoded as in Section 3.2.1 | +-------+-----------------------------------------------------------+ | 26 | Name: EC Public Key (Weierstrass) with | | | brainpoolP512r1 | | | Identifiers: ecPublicKey, id-ecPublicKey | | | OID: 1.2.840.10045.2.1 | | | Parameters: namedCurve = brainpoolP512r1 | | | (1.3.36.3.3.2.8.1.1.13) | | | DER: 30 14 06 07 2A 86 48 CE 3D 02 01 06 09 2B 24 | | | 03 03 02 08 01 01 0D | | | Comments: subjectPublicKey encoded as in Section 3.2.1 | +-------+-----------------------------------------------------------+ | 27 | Name: EC Public Key (Weierstrass) with | | | FRP256v1 | | | Identifiers: ecPublicKey, id-ecPublicKey | | | OID: 1.2.840.10045.2.1 | | | Parameters: namedCurve = FRP256v1 | | | (1.2.250.1.223.101.256.1) | | | DER: 30 15 06 07 2A 86 48 CE 3D 02 01 06 0A 2A 81 | | | 7A 01 81 5F 65 82 00 01 | Preuß Mattsson, et al. Expires 12 November 2026 [Page 61] Internet-Draft C509 Certificates May 2026 | | Comments: subjectPublicKey encoded as in Section 3.2.1 | +-------+-----------------------------------------------------------+ Figure 19: C509 Public Key Algorithms 8.16. COSE Header Parameters Registry IANA is requested to assign the entries in Table 1 to the "COSE Header Parameters" registry in the registry group "CBOR Object Signing and Encryption (COSE)" with this document as reference. 8.17. COSE Header Algorithm Parameters Registry IANA is requested to assign the entries in Table 2 to the "COSE Header Algorithm Parameters" registry in the registry group "CBOR Object Signing and Encryption (COSE)" with this document as reference. 8.18. Media Type Application Registry IANA is requested to assign the following entries into the "application" registry in the registry group "Media Types" with this document as reference. 8.18.1. Media Type application/cose-c509-cert When the application/cose-c509-cert media type is used, the data is a COSE_C509 structure. If the parameter "usage" is set to "chain", this sequence indicates a certificate chain. Type name: application Subtype name: cose-c509-cert Required parameters: N/A Optional parameters: usage * Can be absent to provide no further information about the intended meaning of the order in the CBOR sequence of certificates. * Can be set to "chain" to indicate that the sequence of data items is to be interpreted as a certificate chain. Encoding considerations: binary Security considerations: See the Security Considerations section of [[this document]]. Preuß Mattsson, et al. Expires 12 November 2026 [Page 62] Internet-Draft C509 Certificates May 2026 Interoperability considerations: N/A Published specification: [[this document]] Applications that use this media type: Applications that employ COSE and use C509 as a certificate type. Fragment identifier considerations: N/A Additional information: * Deprecated alias names for this type: N/A * Magic number(s): TBD8, TBD6 * File extension(s): .c509 * Macintosh file type code(s): N/A Person & email address to contact for further information: iesg@ietf.org Intended usage: COMMON Restrictions on usage: N/A Author: COSE WG Change controller: IETF 8.18.2. Media Type application/cose-c509-pkcs10 When the application/cose-c509-pkcs10 media type is used, the data is a C509CertificationRequest structure. Type name: application Subtype name: cose-c509-pkcs10 Required parameters: N/A Optional parameters: N/A Encoding considerations: binary Security considerations: See the Security Considerations section of [[this document]]. Preuß Mattsson, et al. Expires 12 November 2026 [Page 63] Internet-Draft C509 Certificates May 2026 Interoperability considerations: N/A Published specification: [[this document]] Applications that use this media type: Applications that employ COSE and C509 Certification Request. Fragment identifier considerations: N/A Additional information: * Deprecated alias names for this type: N/A * Magic number(s): TBD9 * File extension(s): .c509 * Macintosh file type code(s): N/A Person & email address to contact for further information: iesg@ietf.org Intended usage: COMMON Restrictions on usage: N/A Author: COSE WG Change controller: IETF 8.18.3. Media Type application/cose-c509-crtemplate When the application/cose-c509-crtemplate media type is used, the data is a C509CertificationRequestTemplate structure. Type name: application Subtype name: cose-c509-crtemplate Required parameters: N/A Optional parameters: N/A Encoding considerations: binary Security considerations: See the Security Considerations section of [[this document]]. Preuß Mattsson, et al. Expires 12 November 2026 [Page 64] Internet-Draft C509 Certificates May 2026 Interoperability considerations: N/A Published specification: [[this document]] Applications that use this media type: Applications that employ COSE and C509 Certification Request. Fragment identifier considerations: N/A Additional information: * Deprecated alias names for this type: N/A * Magic number(s): TBD18 * File extension(s): .c509 * Macintosh file type code(s): N/A Person & email address to contact for further information: iesg@ietf.org Intended usage: COMMON Restrictions on usage: N/A Author: COSE WG Change controller: IETF 8.18.4. Media Type application/cose-c509-privkey When the application/cose-c509-privkey media type is used, the data is a C509PrivateKey structure. Type name: application Subtype name: cose-c509-privkey Required parameters: N/A Optional parameters: N/A Encoding considerations: binary Security considerations: See the Security Considerations section of [[this document]]. Preuß Mattsson, et al. Expires 12 November 2026 [Page 65] Internet-Draft C509 Certificates May 2026 Interoperability considerations: N/A Published specification: [[this document]] Applications that use this media type: Applications that employ COSE and use C509 as a certificate type. Fragment identifier considerations: N/A Additional information: * Deprecated alias names for this type: N/A * Magic number(s): TBD12 * File extension(s): .c509 * Macintosh file type code(s): N/A Person & email address to contact for further information: iesg@ietf.org Intended usage: COMMON Restrictions on usage: N/A Author: COSE WG Change controller: IETF 8.18.5. Media Type application/cose-c509-pem When the application/cose-c509-pem media type is used, the data is a C509PEM structure. Type name: application Subtype name: cose-c509-pem Required parameters: N/A Optional parameters: N/A Encoding considerations: binary Security considerations: See the Security Considerations section of [[this document]]. Preuß Mattsson, et al. Expires 12 November 2026 [Page 66] Internet-Draft C509 Certificates May 2026 Interoperability considerations: N/A Published specification: [[this document]] Applications that use this media type: Applications that employ COSE and use C509 as a certificate type. Fragment identifier considerations: N/A Additional information: * Deprecated alias names for this type: N/A * Magic number(s): TBD13 * File extension(s): .c509 * Macintosh file type code(s): N/A Person & email address to contact for further information: iesg@ietf.org Intended usage: COMMON Restrictions on usage: N/A Author: COSE WG Change controller: IETF 8.18.6. Media Type application/cose-certhash When the application/cose-certhash media type is used, the data is a COSE_CertHash structure as defined in [RFC9360]. If the parameter "usage" is set to "c509", the hash value is calculated over a C509 certificate. Type name: application Subtype name: cose-certhash Required parameters: N/A Optional parameters: usage * Can be absent to provide no further information about what the hash value is calculated over. Preuß Mattsson, et al. Expires 12 November 2026 [Page 67] Internet-Draft C509 Certificates May 2026 * Can be set to "c509" to indicate that the COSE_CertHash structure as defined in [RFC9360] is used, with hashValue calculated over a C509 certificate as defined in Section 3.4. Encoding considerations: binary Security considerations: See the Security Considerations section of [RFC9360]. Interoperability considerations: N/A Published specification: [[this document]] Applications that use this media type: Applications that employ COSE and use X.509 or C509 as certificate type. Fragment identifier considerations: N/A Additional information: * Deprecated alias names for this type: N/A * Magic number(s): N/A * File extension(s): N/A * Macintosh file type code(s): N/A Person & email address to contact for further information: iesg@ietf.org Intended usage: COMMON Restrictions on usage: N/A Author: COSE WG Change controller: IETF 8.19. CoAP Content-Formats Registry IANA is requested to add entries for "application/cose-c509-cert", "application/cose-c509-pkcs10", "application/cose-c509-crtemplate", "application/cose-c509-privkey" and "application/cose-c509-pem" to the "CoAP Content-Formats" registry in the registry group "Constrained RESTful Environments (CoRE) Parameters". A dedicated Content-Format ID is requested for the "application/cose-c509-cert" media type in the case when the parameter "usage" is set to "chain", Preuß Mattsson, et al. Expires 12 November 2026 [Page 68] Internet-Draft C509 Certificates May 2026 see Section 8.18.1. IANA is requested to add entries for "application/cose-certhash" to the "CoAP Content-Formats" registry in the registry group "Constrained RESTful Environments (CoRE) Parameters". A dedicated Content-Format ID is requested in the case when the parameter "usage" is set to "c509", see Section 8.18.6. IANA is requested to add entries for "application/cbor" to the "CoAP Content-Formats" registry in the registry group "Constrained RESTful Environments (CoRE) Parameters", in the case when the encoding is a CBOR text string containing a URI, see [RFC3986]. +----------------------+---------+-----------+-------+------------+ | Content | Content | Media | ID | Reference | | Format | Coding | Type | | | +======================+=========+===========+=======+============+ | application/ | - | [[link | TBD3 | [[this | | cose-c509-cert | | to 8.18]] | | document]] | +----------------------+---------+-----------+-------+------------+ | application/ | | [[link | | [[this | | cose-c509-cert; | - | to 8.18]] | TBD15 | document]] | | usage=chain | | | | | +----------------------+---------+-----------+-------+------------+ | application/ | - | [[link | TBD4 | [[this | | cose-c509-pkcs10 | | to 8.18]] | | document]] | +----------------------+---------+-----------+-------+------------+ | application/ | - | [[link | TBD19 | [[this | | cose-c509-crtemplate | | to 8.18]] | | document]] | +----------------------+---------+-----------+-------+------------+ | application/ | - | [[link | TBD10 | [[this | | cose-c509-privkey | | to 8.18]] | | document]] | +----------------------+---------+-----------+-------+------------+ | application/ | - | [[link | TBD11 | [[this | | cose-c509-pem | | to 8.18]] | | document]] | +----------------------+---------+-----------+-------+------------+ | application/ | - | [[link | TBD16 | [[this | | cose-certhash | | to 8.18]] | | document]] | +----------------------+---------+-----------+-------+------------+ | application/ | | [[link | | [[this | | cose-certhash; | - | to 8.18]] | TBD17 | document]] | | usage=c509 | | | | | +----------------------+---------+-----------+-------+------------+ Figure 20: CoAP Content-Format IDs Preuß Mattsson, et al. Expires 12 November 2026 [Page 69] Internet-Draft C509 Certificates May 2026 8.20. TLS Certificate Types Registry This document registers the following entry in the "TLS Certificate Types" registry in the registry group "Transport Layer Security (TLS) Extensions". The new certificate type can be used with additional TLS certificate compression [RFC8879]. For TLS 1.3, the C509 certificate type is defined as a new case in the CertificateEntry struct specified in Section 4.4.2 of [RFC8446]: case C509: opaque c509_data<1..2^24-1>; where c509_data is the CBOR sequence ~C509Certificate (an unwrapped C509Certificate). For TLS 1.2 the same construction is applied with a similar union type defined for the Certificate struct in Section 7.4.2 of [RFC5246]. Note that, similar to COSE_C509, the TLS handshake contains the length of each certificate. The TLS extensions client_certificate_type and server_certificate_type [RFC7250] are used to negotiate the use of C509. +-------+------------------+-------------+--------------------------+ | Value | Name | Recommended | Comment | +=======+==================+=============+==========================+ | TBD5 | C509 Certificate | N | | +-------+------------------+-------------+--------------------------+ 8.21. TLSA Selectors Registry This document registers the following entry in the "TLSA Selectors" registry in the registry group "DNS-Based Authentication of Named Entities (DANE) Parameters". The C509 certificate data, C509CertData, is defined in Section 3.4. +-------+---------+------------------------+-------------------+ | Value | Acronym | Short Description | Reference | +=======+=========+========================+===================+ | TBD7 | C509 | C509 certificate data | [[this document]] | +-------+---------+------------------------+-------------------+ The TLSA selectors registry defined in [RFC6698] originally only applied to PKIX [RFC5280] certificates in DER encoding. This specification updates [RFC6698] to accept the use of C509 certificates. Preuß Mattsson, et al. Expires 12 November 2026 [Page 70] Internet-Draft C509 Certificates May 2026 8.22. EDHOC Authentication Credential Types Registry This document registers the following entry in the "EDHOC Authentication Credential Types" registry in the registry group "Ephemeral Diffie-Hellman Over COSE (EDHOC)". This is useful to identify C509 certificates as a supported authentication credential type to use with EDHOC [RFC9528], for example, during discovery of EDHOC resources, see [RFC9668]. +-------+----------------------+-------------------+ | Value | Description | Reference | +=======+======================+===================+ | 3 | C509 certificate | [[this document]] | +-------+----------------------+-------------------+ 8.23. Relative Distinguished Name Attribute This document registers the following entry in the "SMI Security for PKIX Relative Distinguished Name Attribute" registry [RFC7299]: +---------+----------------------+-------------------+ | Decimal | Description | Reference | +=========+======================+===================+ | TBD30 | id-rdna-c509Name | [[this document]] | +---------+----------------------+-------------------+ 9. References 9.1. Normative References [I-D.ietf-lamps-macaddress-on] Housley, R., Bonnell, C., Mandel, J., Okubo, T., and M. StJohns, "Media Access Control (MAC) Addresses in X.509 Certificates", Work in Progress, Internet-Draft, draft- ietf-lamps-macaddress-on-07, 12 March 2026, . [POSIX] "IEEE Standard for Information Technology--Portable Operating System Interface (POSIX(TM)) Base Specifications, Issue 7", January 2018, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . Preuß Mattsson, et al. Expires 12 November 2026 [Page 71] Internet-Draft C509 Certificates May 2026 [RFC2985] Nystrom, M. and B. Kaliski, "PKCS #9: Selected Object Classes and Attribute Types Version 2.0", RFC 2985, DOI 10.17487/RFC2985, November 2000, . [RFC2986] Nystrom, M. and B. Kaliski, "PKCS #10: Certification Request Syntax Specification Version 1.7", RFC 2986, DOI 10.17487/RFC2986, November 2000, . [RFC3779] Lynn, C., Kent, S., and K. Seo, "X.509 Extensions for IP Addresses and AS Identifiers", RFC 3779, DOI 10.17487/RFC3779, June 2004, . [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, DOI 10.17487/RFC3986, January 2005, . [RFC4108] Housley, R., "Using Cryptographic Message Syntax (CMS) to Protect Firmware Packages", RFC 4108, DOI 10.17487/RFC4108, August 2005, . [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/RFC5246, August 2008, . [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., Housley, R., and W. Polk, "Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008, . [RFC5958] Turner, S., "Asymmetric Key Packages", RFC 5958, DOI 10.17487/RFC5958, August 2010, . [RFC6066] Eastlake 3rd, D., "Transport Layer Security (TLS) Extensions: Extension Definitions", RFC 6066, DOI 10.17487/RFC6066, January 2011, . Preuß Mattsson, et al. Expires 12 November 2026 [Page 72] Internet-Draft C509 Certificates May 2026 [RFC6698] Hoffman, P. and J. Schlyter, "The DNS-Based Authentication of Named Entities (DANE) Transport Layer Security (TLS) Protocol: TLSA", RFC 6698, DOI 10.17487/RFC6698, August 2012, . [RFC7030] Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed., "Enrollment over Secure Transport", RFC 7030, DOI 10.17487/RFC7030, October 2013, . [RFC7120] Cotton, M., "Early IANA Allocation of Standards Track Code Points", BCP 100, RFC 7120, DOI 10.17487/RFC7120, January 2014, . [RFC7250] Wouters, P., Ed., Tschofenig, H., Ed., Gilmore, J., Weiler, S., and T. Kivinen, "Using Raw Public Keys in Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS)", RFC 7250, DOI 10.17487/RFC7250, June 2014, . [RFC7299] Housley, R., "Object Identifier Registry for the PKIX Working Group", RFC 7299, DOI 10.17487/RFC7299, July 2014, . [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, June 2017, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8295] Turner, S., "EST (Enrollment over Secure Transport) Extensions", RFC 8295, DOI 10.17487/RFC8295, January 2018, . [RFC8360] Huston, G., Michaelson, G., Martinez, C., Bruijnzeels, T., Newton, A., and D. Shaw, "Resource Public Key Infrastructure (RPKI) Validation Reconsidered", RFC 8360, DOI 10.17487/RFC8360, April 2018, . [RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data Definition Language (CDDL): A Notational Convention to Express Concise Binary Object Representation (CBOR) and JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610, June 2019, . Preuß Mattsson, et al. Expires 12 November 2026 [Page 73] Internet-Draft C509 Certificates May 2026 [RFC8742] Bormann, C., "Concise Binary Object Representation (CBOR) Sequences", RFC 8742, DOI 10.17487/RFC8742, February 2020, . [RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object Representation (CBOR)", STD 94, RFC 8949, DOI 10.17487/RFC8949, December 2020, . [RFC9052] Schaad, J., "CBOR Object Signing and Encryption (COSE): Structures and Process", STD 96, RFC 9052, DOI 10.17487/RFC9052, August 2022, . [RFC9053] Schaad, J., "CBOR Object Signing and Encryption (COSE): Initial Algorithms", RFC 9053, DOI 10.17487/RFC9053, August 2022, . [RFC9090] Bormann, C., "Concise Binary Object Representation (CBOR) Tags for Object Identifiers", RFC 9090, DOI 10.17487/RFC9090, July 2021, . [RFC9277] Richardson, M. and C. Bormann, "On Stable Storage for Items in Concise Binary Object Representation (CBOR)", RFC 9277, DOI 10.17487/RFC9277, August 2022, . [RFC9360] Schaad, J., "CBOR Object Signing and Encryption (COSE): Header Parameters for Carrying and Referencing X.509 Certificates", RFC 9360, DOI 10.17487/RFC9360, February 2023, . [RFC9542] Eastlake 3rd, D., Abley, J., and Y. Li, "IANA Considerations and IETF Protocol and Documentation Usage for IEEE 802 Parameters", BCP 141, RFC 9542, DOI 10.17487/RFC9542, April 2024, . [RFC9549] Housley, R., "Internationalization Updates to RFC 5280", RFC 9549, DOI 10.17487/RFC9549, March 2024, . [RFC9598] Melnikov, A., Chuang, W., and C. Bonnell, "Internationalized Email Addresses in X.509 Certificates", RFC 9598, DOI 10.17487/RFC9598, May 2024, . Preuß Mattsson, et al. Expires 12 November 2026 [Page 74] Internet-Draft C509 Certificates May 2026 [RFC9668] Palombini, F., Tiloca, M., Höglund, R., Hristozov, S., and G. Selander, "Using Ephemeral Diffie-Hellman Over COSE (EDHOC) with the Constrained Application Protocol (CoAP) and Object Security for Constrained RESTful Environments (OSCORE)", RFC 9668, DOI 10.17487/RFC9668, November 2024, . [RFC9883] Housley, R., "An Attribute for Statement of Possession of a Private Key", RFC 9883, DOI 10.17487/RFC9883, October 2025, . [SECG] "Elliptic Curve Cryptography, Standards for Efficient Cryptography Group, ver. 2", 2009, . [Wi-SUN] "Wi-SUN Alliance", n.d., . [X.501] "Information Technology - Open Systems Interconnection - The Directory: Models, ITU-T X.501", December 2019, . [X.520] "Information Technology - Open Systems Interconnection - The Directory: Selected attribute types", October 2019, . [X.690] "ASN.1 encoding rules. Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER)", n.d., . 9.2. Informative References [CAB-Code] CA/Browser Forum, "CA/Browser Forum, "Baseline Requirements for the Issuance and Management of Publicly- Trusted Code Signing Certificates Version 3.8.0"", August 2024, . [CAB-TLS] CA/Browser Forum, "CA/Browser Forum, "Baseline Requirements for the Issuance and Management of Publicly- Trusted Certificates Version 2.1.4"", March 2025, . [CborMe] Bormann, C., "CBOR Playground", May 2018, . Preuß Mattsson, et al. Expires 12 November 2026 [Page 75] Internet-Draft C509 Certificates May 2026 [GSMA-eUICC] GSMA, "GSMA eUICC PKI Certificate Policy Version 2.2", January 2025, . [GSMA-SGP.22] "GSMA RSP Technical Specification Version 3.1 Final", December 2023, . [IANA-AFI] "Address Family Numbers", n.d., . [IANA-CBOR-TAGS] IANA, "Concise Binary Object Representation (CBOR) Tags", n.d., . [IANA-SAFI] "Subsequent Address Family Identifiers (SAFI) Parameters", n.d., . [IEEE-802.1AR] Institute of Electrical and Electronics Engineers, "IEEE Standard for Local and metropolitan area networks–Secure Device Identity", IEEE Standard 802.1AR-2018 , August 2018, . [RFC3161] Adams, C., Cain, P., Pinkas, D., and R. Zuccherato, "Internet X.509 Public Key Infrastructure Time-Stamp Protocol (TSP)", RFC 3161, DOI 10.17487/RFC3161, August 2001, . [RFC4524] Zeilenga, K., Ed., "COSINE LDAP/X.500 Schema", RFC 4524, DOI 10.17487/RFC4524, June 2006, . [RFC6487] Huston, G., Michaelson, G., and R. Loomans, "A Profile for X.509 PKIX Resource Certificates", RFC 6487, DOI 10.17487/RFC6487, February 2012, . Preuß Mattsson, et al. Expires 12 November 2026 [Page 76] Internet-Draft C509 Certificates May 2026 [RFC6955] Schaad, J. and H. Prafullchandra, "Diffie-Hellman Proof- of-Possession Algorithms", RFC 6955, DOI 10.17487/RFC6955, May 2013, . [RFC6960] Santesson, S., Myers, M., Ankney, R., Malpani, A., Galperin, S., and C. Adams, "X.509 Internet Public Key Infrastructure Online Certificate Status Protocol - OCSP", RFC 6960, DOI 10.17487/RFC6960, June 2013, . [RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for Constrained-Node Networks", RFC 7228, DOI 10.17487/RFC7228, May 2014, . [RFC7468] Josefsson, S. and S. Leonard, "Textual Encodings of PKIX, PKCS, and CMS Structures", RFC 7468, DOI 10.17487/RFC7468, April 2015, . [RFC7925] Tschofenig, H., Ed. and T. Fossati, "Transport Layer Security (TLS) / Datagram Transport Layer Security (DTLS) Profiles for the Internet of Things", RFC 7925, DOI 10.17487/RFC7925, July 2016, . [RFC7932] Alakuijala, J. and Z. Szabadka, "Brotli Compressed Data Format", RFC 7932, DOI 10.17487/RFC7932, July 2016, . [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, . [RFC8603] Jenkins, M. and L. Zieglar, "Commercial National Security Algorithm (CNSA) Suite Certificate and Certificate Revocation List (CRL) Profile", RFC 8603, DOI 10.17487/RFC8603, May 2019, . [RFC8879] Ghedini, A. and V. Vasiliev, "TLS Certificate Compression", RFC 8879, DOI 10.17487/RFC8879, December 2020, . [RFC9000] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based Multiplexed and Secure Transport", RFC 9000, DOI 10.17487/RFC9000, May 2021, . Preuß Mattsson, et al. Expires 12 November 2026 [Page 77] Internet-Draft C509 Certificates May 2026 [RFC9147] Rescorla, E., Tschofenig, H., and N. Modadugu, "The Datagram Transport Layer Security (DTLS) Protocol Version 1.3", RFC 9147, DOI 10.17487/RFC9147, April 2022, . [RFC9148] van der Stok, P., Kampanakis, P., Richardson, M., and S. Raza, "EST-coaps: Enrollment over Secure Transport with the Secure Constrained Application Protocol", RFC 9148, DOI 10.17487/RFC9148, April 2022, . [RFC9190] Preuß Mattsson, J. and M. Sethi, "EAP-TLS 1.3: Using the Extensible Authentication Protocol with TLS 1.3", RFC 9190, DOI 10.17487/RFC9190, February 2022, . [RFC9191] Sethi, M., Preuß Mattsson, J., and S. Turner, "Handling Large Certificates and Long Certificate Chains in TLS- Based EAP Methods", RFC 9191, DOI 10.17487/RFC9191, February 2022, . [RFC9528] Selander, G., Preuß Mattsson, J., and F. Palombini, "Ephemeral Diffie-Hellman Over COSE (EDHOC)", RFC 9528, DOI 10.17487/RFC9528, March 2024, . [RFC9908] Richardson, M., Ed., Friel, O., von Oheimb, D., and D. Harkins, "Clarification and Enhancement of the CSR Attributes Definition in RFC 7030", RFC 9908, DOI 10.17487/RFC9908, January 2026, . [SP-800-56A] Barker, E., Chen, L., Roginsky, A., Vassilev, A., and R. Davis, "Recommendation for Pair-Wise Key-Establishment Schemes Using Discrete Logarithm Cryptography", NIST Special Publication 800-56A Revision 3, April 2018, . [X.509-IoT] Forsby, F., Furuhed, M., Papadimitratos, P., and S. Raza, "Lightweight X.509 Digital Certificates for the Internet of Things.", Springer, Cham. Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, vol 242., July 2018, . Preuß Mattsson, et al. Expires 12 November 2026 [Page 78] Internet-Draft C509 Certificates May 2026 Appendix A. C509 Certificate Examples A.1. Example: RFC 7925 profiled X.509 Certificate Example of an [RFC7925] profiled X.509 certificate parsed with OpenSSL. Certificate: Data: Version: 3 (0x2) Serial Number: 128269 (0x1f50d) Signature Algorithm: ecdsa-with-SHA256 Issuer: CN=RFC test CA Validity Not Before: Jan 1 00:00:00 2023 GMT Not After : Jan 1 00:00:00 2026 GMT Subject: CN=01-23-45-FF-FE-67-89-AB Subject Public Key Info: Public Key Algorithm: id-ecPublicKey Public-Key: (256 bit) pub: 04:b1:21:6a:b9:6e:5b:3b:33:40:f5:bd:f0:2e:69: 3f:16:21:3a:04:52:5e:d4:44:50:b1:01:9c:2d:fd: 38:38:ab:ac:4e:14:d8:6c:09:83:ed:5e:9e:ef:24: 48:c6:86:1c:c4:06:54:71:77:e6:02:60:30:d0:51: f7:79:2a:c2:06 ASN1 OID: prime256v1 NIST CURVE: P-256 X509v3 extensions: X509v3 Key Usage: Digital Signature Signature Algorithm: ecdsa-with-SHA256 30:46:02:21:00:d4:32:0b:1d:68:49:e3:09:21:9d:30:03:7e: 13:81:66:f2:50:82:47:dd:da:e7:6c:ce:ea:55:05:3c:10:8e: 90:02:21:00:d5:51:f6:d6:01:06:f1:ab:b4:84:cf:be:62:56: c1:78:e4:ac:33:14:ea:19:19:1e:8b:60:7d:a5:ae:3b:da:16 The DER encoding of the above certificate is 316 bytes. Preuß Mattsson, et al. Expires 12 November 2026 [Page 79] Internet-Draft C509 Certificates May 2026 30 82 01 38 30 81 de a0 03 02 01 02 02 03 01 f5 0d 30 0a 06 08 2a 86 48 ce 3d 04 03 02 30 16 31 14 30 12 06 03 55 04 03 0c 0b 52 46 43 20 74 65 73 74 20 43 41 30 1e 17 0d 32 33 30 31 30 31 30 30 30 30 30 30 5a 17 0d 32 36 30 31 30 31 30 30 30 30 30 30 5a 30 22 31 20 30 1e 06 03 55 04 03 0c 17 30 31 2d 32 33 2d 34 35 2d 46 46 2d 46 45 2d 36 37 2d 38 39 2d 41 42 30 59 30 13 06 07 2a 86 48 ce 3d 02 01 06 08 2a 86 48 ce 3d 03 01 07 03 42 00 04 b1 21 6a b9 6e 5b 3b 33 40 f5 bd f0 2e 69 3f 16 21 3a 04 52 5e d4 44 50 b1 01 9c 2d fd 38 38 ab ac 4e 14 d8 6c 09 83 ed 5e 9e ef 24 48 c6 86 1c c4 06 54 71 77 e6 02 60 30 d0 51 f7 79 2a c2 06 a3 0f 30 0d 30 0b 06 03 55 1d 0f 04 04 03 02 07 80 30 0a 06 08 2a 86 48 ce 3d 04 03 02 03 49 00 30 46 02 21 00 d4 32 0b 1d 68 49 e3 09 21 9d 30 03 7e 13 81 66 f2 50 82 47 dd da e7 6c ce ea 55 05 3c 10 8e 90 02 21 00 d5 51 f6 d6 01 06 f1 ab b4 84 cf be 62 56 c1 78 e4 ac 33 14 ea 19 19 1e 8b 60 7d a5 ae 3b da 16 A.1.1. Example: C509 Certificate Encoding This section shows the C509 encoding of the X.509 certificate in the previous section. The point-compressed public key is represented as described in Section 3.2.1. Figure 21 shows the diagnostic notation of the unwrapped CBOR sequence, ~C509Certificate, see Section 3.1. /This defines a CBOR Sequence (RFC 8742):/ 3, / version and certificate type / h'01f50d', / certificateSerialNumber / 0, / signatureAlgorithm / "RFC test CA", / issuer / 1672531200, / notBefore / 1767225600, / notAfter / 48(h'0123456789AB'), / subject, EUI-64 / 1, / subjectPublicKeyAlgorithm / h'FEB1216AB96E5B3B3340F5BDF02E693F16213A04525ED44450 B1019C2DFD3838AB', 1, / single extension: non-critical keyUsage digitalSignature / h'D4320B1D6849E309219D30037E138166F2508247DDDAE76CCE EA55053C108E90D551F6D60106F1ABB484CFBE6256C178E4AC 3314EA19191E8B607DA5AE3BDA16' Figure 21: CBOR diagnostic notation of ~C509Certificate Figure 22 shows the plain hex format of the unwrapped CBOR sequence. The size is 140 bytes. Preuß Mattsson, et al. Expires 12 November 2026 [Page 80] Internet-Draft C509 Certificates May 2026 03 43 01 F5 0D 00 6B 52 46 43 20 74 65 73 74 20 43 41 1A 63 B0 CD 00 1A 69 55 B9 00 D8 30 46 01 23 45 67 89 AB 01 58 21 FE B1 21 6A B9 6E 5B 3B 33 40 F5 BD F0 2E 69 3F 16 21 3A 04 52 5E D4 44 50 B1 01 9C 2D FD 38 38 AB 01 58 40 D4 32 0B 1D 68 49 E3 09 21 9D 30 03 7E 13 81 66 F2 50 82 47 DD DA E7 6C CE EA 55 05 3C 10 8E 90 D5 51 F6 D6 01 06 F1 AB B4 84 CF BE 62 56 C1 78 E4 AC 33 14 EA 19 19 1E 8B 60 7D A5 AE 3B DA 16 Figure 22: CBOR plain hex format of ~C509Certificate. A.1.2. Example: Natively Signed C509 Certificate This section shows the natively signed C509 certificate corresponding to the certificate in the previous section. It is identical except for c509CertificateType, the encoding of point compression (see Section 3.2.1), and signatureValue. Figure 23 shows the diagnostic notation of the natively signed unwrapped CBOR sequence, ~C509Certificate. /This defines a CBOR Sequence (RFC 8742):/ 2, h'01f50d', 0, "RFC test CA", 1672531200, 1767225600, 48(h'0123456789AB'), 1, h'02B1216AB96E5B3B3340F5BDF02E693F16213A04525ED44450 B1019C2DFD3838AB', 1, h'EB0D472731F689BC00F5880B12C68B3F9FD38B23FADFCA2095 0F3F241B60A202579CAC28CD3B7494D5FA5D8BBAB4600357E5 50AB9FA9A65D9BA2B3B82E668CC6' Figure 23: CBOR diagnostic notation of ~C509Certificate Figure 24 shows the plain hex format of the natively signed unwrapped CBOR sequence. The size is 140 bytes. Preuß Mattsson, et al. Expires 12 November 2026 [Page 81] Internet-Draft C509 Certificates May 2026 02 43 01 F5 0D 00 6B 52 46 43 20 74 65 73 74 20 43 41 1A 63 B0 CD 00 1A 69 55 B9 00 D8 30 46 01 23 45 67 89 AB 01 58 21 02 B1 21 6A B9 6E 5B 3B 33 40 F5 BD F0 2E 69 3F 16 21 3A 04 52 5E D4 44 50 B1 01 9C 2D FD 38 38 AB 01 58 40 EB 0D 47 27 31 F6 89 BC 00 F5 88 0B 12 C6 8B 3F 9F D3 8B 23 FA DF CA 20 95 0F 3F 24 1B 60 A2 02 57 9C AC 28 CD 3B 74 94 D5 FA 5D 8B BA B4 60 03 57 E5 50 AB 9F A9 A6 5D 9B A2 B3 B8 2E 66 8C C6 Figure 24: CBOR plain hex format of ~C509Certificate. A.1.3. C509 for Diffie-Hellman keys The two previous examples illustrate keyUsage digitalSignature. A C509 certificate for a public Diffie-Hellman key would instead have key usage keyAgreement encoded according to Section 3.3 (in this case of single extension encoded as integer 16 instead of 1 for digital signature) but otherwise identical in format. Note that Section 5.6.3.2 of [SP-800-56A] allows a key agreement key pair to be used to sign a certification request. A.1.4. Example: Additional Keys for the Example Certificates Below are the issuer key pair and the subject private key corresponding to the above example certificates. The private keys are encoded as in COSE [RFC9052]. This issuer key pair can be used to sign or verify the example certificates, and the subject private key allows those certificates to be used in test vectors for other protocols such as EDHOC. issuerPublicKeyAlgorithm : 1 (EC Public Key (Weierstrass) with secp256r1) issuerPublicKey : h'02AE4CDB01F614DEFC7121285FDC7F5C6D1D42C95647F061BA0080DF678867845E' issuerPrivateKey : h'DC66B3415456D649429B53223DF7532B942D6B0E0842C30BCA4C0ACF91547BB2' subjectPrivateKey : h'D718111F3F9BD91B92FF6877F386BDBFCEA7154268FD7F2FB56EE17D99EA16D4' Preuß Mattsson, et al. Expires 12 November 2026 [Page 82] Internet-Draft C509 Certificates May 2026 A.1.5. Examples: C509Certificate and C509CertData This section exemplifies other CBOR objects defined in this specification, based on the natively signed C509 certificate in Appendix A.1.2. Figure 25 shows the encoding of the corresponding C509Certificate, i.e., the CBOR array wrapping of the CBOR sequence ~C509Certificate, see Section 3.1. 8B 02 43 01 F5 0D 00 6B 52 46 43 20 74 65 73 74 20 43 41 1A 63 B0 CD 00 1A 69 55 B9 00 D8 30 46 01 23 45 67 89 AB 01 58 21 02 B1 21 6A B9 6E 5B 3B 33 40 F5 BD F0 2E 69 3F 16 21 3A 04 52 5E D4 44 50 B1 01 9C 2D FD 38 38 AB 01 58 40 EB 0D 47 27 31 F6 89 BC 00 F5 88 0B 12 C6 8B 3F 9F D3 8B 23 FA DF CA 20 95 0F 3F 24 1B 60 A2 02 57 9C AC 28 CD 3B 74 94 D5 FA 5D 8B BA B4 60 03 57 E5 50 AB 9F A9 A6 5D 9B A2 B3 B8 2E 66 8C C6 Figure 25: C509Certificate: The CBOR array wrapping of ~C509Certificate Note that C509Certificate is identical to ~C509Certificate in Appendix A.1.2 except for the prefix 8B (which indicates that it is a CBOR array with 11 elements). Figure 26 shows the encoding of the corresponding C509CertData, i.e., the CBOR byte string wrapping of the CBOR sequence ~C509Certificate, see Section 3.4. Preuß Mattsson, et al. Expires 12 November 2026 [Page 83] Internet-Draft C509 Certificates May 2026 58 8C 02 43 01 F5 0D 00 6B 52 46 43 20 74 65 73 74 20 43 41 1A 63 B0 CD 00 1A 69 55 B9 00 D8 30 46 01 23 45 67 89 AB 01 58 21 02 B1 21 6A B9 6E 5B 3B 33 40 F5 BD F0 2E 69 3F 16 21 3A 04 52 5E D4 44 50 B1 01 9C 2D FD 38 38 AB 01 58 40 EB 0D 47 27 31 F6 89 BC 00 F5 88 0B 12 C6 8B 3F 9F D3 8B 23 FA DF CA 20 95 0F 3F 24 1B 60 A2 02 57 9C AC 28 CD 3B 74 94 D5 FA 5D 8B BA B4 60 03 57 E5 50 AB 9F A9 A6 5D 9B A2 B3 B8 2E 66 8C C6 Figure 26: C509CertData: CBOR byte string wrapping of ~C509Certificate. Note that C509CertData is identical to ~C509Certificate in Appendix A.1.2 except for the prefix 58 8C (which indicates that it is a CBOR byte string of 140 bytes). A.2. Example: IEEE 802.1AR profiled X.509 Certificate An example of an IEEE 802.1AR profiled X.509 certificate (Secure Device Identifier, DevID) is provided in Appendix C.2 of [RFC9148]. The certificate is shown below including details of the hardwareModuleName type of otherName in subjectAltName, see Section 3.3. Preuß Mattsson, et al. Expires 12 November 2026 [Page 84] Internet-Draft C509 Certificates May 2026 Certificate: Data: Version: 3 (0x2) Serial Number: 9112578475118446130 (0x7e7661d7b54e4632) Signature Algorithm: ecdsa-with-SHA256 Issuer: C=US, ST=CA, O=Example Inc, OU=certification, CN=802.1AR CA Validity Not Before: Jan 31 11:29:16 2019 GMT Not After : Dec 31 23:59:59 9999 GMT Subject: C=US, ST=CA, L=LA, O=example Inc, OU=IoT/serialNumber=Wt1234 Subject Public Key Info: Public Key Algorithm: id-ecPublicKey Public-Key: (256 bit) pub: 04:c8:b4:21:f1:1c:25:e4:7e:3a:c5:71:23:bf:2d: 9f:dc:49:4f:02:8b:c3:51:cc:80:c0:3f:15:0b:f5: 0c:ff:95:8d:75:41:9d:81:a6:a2:45:df:fa:e7:90: be:95:cf:75:f6:02:f9:15:26:18:f8:16:a2:b2:3b: 56:38:e5:9f:d9 ASN1 OID: prime256v1 NIST CURVE: P-256 X509v3 extensions: X509v3 Basic Constraints: CA:FALSE X509v3 Subject Key Identifier: 96:60:0D:87:16:BF:7F:D0:E7:52:D0:AC:76:07:77:AD:66:5D:02:A0 X509v3 Authority Key Identifier: 68:D1:65:51:F9:51:BF:C8:2A:43:1D:0D:9F:08:BC:2D:20:5B:11:60 X509v3 Key Usage: critical Digital Signature, Key Encipherment X509v3 Subject Alternative Name: otherName: type-id: 1.3.6.1.5.5.7.8.4 (id-on-hardwareModuleName) value: hwType: 1.3.6.1.4.1.6715.10.1 hwSerialNum: 01:02:03:04 Signature Algorithm: ecdsa-with-SHA256 Signature Value: 30:46:02:21:00:c0:d8:19:96:d2:50:7d:69:3f:3c:48:ea:a5: ee:94:91:bd:a6:db:21:40:99:d9:81:17:c6:3b:36:13:74:cd: 86:02:21:00:a7:74:98:9f:4c:32:1a:5c:f2:5d:83:2a:4d:33: 6a:08:ad:67:df:20:f1:50:64:21:18:8a:0a:de:6d:34:92:36 The DER encoding of the certificate is 577 bytes: Preuß Mattsson, et al. Expires 12 November 2026 [Page 85] Internet-Draft C509 Certificates May 2026 30 82 02 3D 30 82 01 E2 A0 03 02 01 02 02 08 7E 76 61 D7 B5 4E 46 32 30 0A 06 08 2A 86 48 CE 3D 04 03 02 30 5D 31 0B 30 09 06 03 55 04 06 13 02 55 53 31 0B 30 09 06 03 55 04 08 0C 02 43 41 31 14 30 12 06 03 55 04 0A 0C 0B 45 78 61 6D 70 6C 65 20 49 6E 63 31 16 30 14 06 03 55 04 0B 0C 0D 63 65 72 74 69 66 69 63 61 74 69 6F 6E 31 13 30 11 06 03 55 04 03 0C 0A 38 30 32 2E 31 41 52 20 43 41 30 20 17 0D 31 39 30 31 33 31 31 31 32 39 31 36 5A 18 0F 39 39 39 39 31 32 33 31 32 33 35 39 35 39 5A 30 5C 31 0B 30 09 06 03 55 04 06 13 02 55 53 31 0B 30 09 06 03 55 04 08 0C 02 43 41 31 0B 30 09 06 03 55 04 07 0C 02 4C 41 31 14 30 12 06 03 55 04 0A 0C 0B 65 78 61 6D 70 6C 65 20 49 6E 63 31 0C 30 0A 06 03 55 04 0B 0C 03 49 6F 54 31 0F 30 0D 06 03 55 04 05 13 06 57 74 31 32 33 34 30 59 30 13 06 07 2A 86 48 CE 3D 02 01 06 08 2A 86 48 CE 3D 03 01 07 03 42 00 04 C8 B4 21 F1 1C 25 E4 7E 3A C5 71 23 BF 2D 9F DC 49 4F 02 8B C3 51 CC 80 C0 3F 15 0B F5 0C FF 95 8D 75 41 9D 81 A6 A2 45 DF FA E7 90 BE 95 CF 75 F6 02 F9 15 26 18 F8 16 A2 B2 3B 56 38 E5 9F D9 A3 81 8A 30 81 87 30 09 06 03 55 1D 13 04 02 30 00 30 1D 06 03 55 1D 0E 04 16 04 14 96 60 0D 87 16 BF 7F D0 E7 52 D0 AC 76 07 77 AD 66 5D 02 A0 30 1F 06 03 55 1D 23 04 18 30 16 80 14 68 D1 65 51 F9 51 BF C8 2A 43 1D 0D 9F 08 BC 2D 20 5B 11 60 30 0E 06 03 55 1D 0F 01 01 FF 04 04 03 02 05 A0 30 2A 06 03 55 1D 11 04 23 30 21 A0 1F 06 08 2B 06 01 05 05 07 08 04 A0 13 30 11 06 09 2B 06 01 04 01 B4 3B 0A 01 04 04 01 02 03 04 30 0A 06 08 2A 86 48 CE 3D 04 03 02 03 49 00 30 46 02 21 00 C0 D8 19 96 D2 50 7D 69 3F 3C 48 EA A5 EE 94 91 BD A6 DB 21 40 99 D9 81 17 C6 3B 36 13 74 CD 86 02 21 00 A7 74 98 9F 4C 32 1A 5C F2 5D 83 2A 4D 33 6A 08 AD 67 DF 20 F1 50 64 21 18 8A 0A DE 6D 34 92 36 A.2.1. Example: C509 Certificate Encoding The CBOR encoding (~C509Certificate) of the same X.509 certificate is shown below in CBOR diagnostic format. Preuß Mattsson, et al. Expires 12 November 2026 [Page 86] Internet-Draft C509 Certificates May 2026 /This defines a CBOR Sequence (RFC 8742):/ 3, h'7E7661D7B54E4632', 0, [ -4, "US", 6, "CA", 8, "Example Inc", 9, "certification", 1, "802.1AR CA" ], 1548934156, null, [ -4, "US", 6, "CA", 5, "LA", 8, "example Inc", 9, "IoT", -3, "Wt1234" ], 1, h'FDC8B421F11C25E47E3AC57123BF2D9FDC494F028BC351CC80C03F150BF50CFF 95', [ 4, -2, 1, h'96600D8716BF7FD0E752D0AC760777AD665D02A0', 7, h'68D16551F951BFC82A431D0D9F08BC2D205B1160', -2, 5, 3, [-1, [h'2B06010401B43B0A01', h'01020304']] / subjectAltName with hardwareModuleName / ], h'C0D81996D2507D693F3C48EAA5EE9491BDA6DB214099D98117C63B361374CD86 A774989F4C321A5CF25D832A4D336A08AD67DF20F1506421188A0ADE6D349236' The size of the CBOR encoding (CBOR sequence) is 275 bytes: Preuß Mattsson, et al. Expires 12 November 2026 [Page 87] Internet-Draft C509 Certificates May 2026 03 48 7E 76 61 D7 B5 4E 46 32 00 8A 23 62 55 53 06 62 43 41 08 6B 45 78 61 6D 70 6C 65 20 49 6E 63 09 6D 63 65 72 74 69 66 69 63 61 74 69 6F 6E 01 6A 38 30 32 2E 31 41 52 20 43 41 1A 5C 52 DC 0C F6 8C 23 62 55 53 06 62 43 41 05 62 4C 41 08 6B 65 78 61 6D 70 6C 65 20 49 6E 63 09 63 49 6F 54 22 66 57 74 31 32 33 34 01 58 21 FD C8 B4 21 F1 1C 25 E4 7E 3A C5 71 23 BF 2D 9F DC 49 4F 02 8B C3 51 CC 80 C0 3F 15 0B F5 0C FF 95 8A 04 21 01 54 96 60 0D 87 16 BF 7F D0 E7 52 D0 AC 76 07 77 AD 66 5D 02 A0 07 54 68 D1 65 51 F9 51 BF C8 2A 43 1D 0D 9F 08 BC 2D 20 5B 11 60 21 05 03 82 20 82 49 2B 06 01 04 01 B4 3B 0A 01 44 01 02 03 04 58 40 C0 D8 19 96 D2 50 7D 69 3F 3C 48 EA A5 EE 94 91 BD A6 DB 21 40 99 D9 81 17 C6 3B 36 13 74 CD 86 A7 74 98 9F 4C 32 1A 5C F2 5D 83 2A 4D 33 6A 08 AD 67 DF 20 F1 50 64 21 18 8A 0A DE 6D 34 92 36 A.3. Example: CAB Baseline ECDSA HTTPS X.509 Certificate The www.ietf.org HTTPS server replies with a certificate message with 2 certificates. The DER encoding of the first certificate is 1209 bytes. 30 82 04 b5 30 82 04 5a a0 03 02 01 02 02 10 04 7f a1 e3 19 28 ee 40 3b a0 b8 3a 39 56 73 fc 30 0a 06 08 2a 86 48 ce 3d 04 03 02 30 4a 31 0b 30 09 06 03 55 04 06 13 02 55 53 31 19 30 17 06 03 55 04 0a 13 10 43 6c 6f 75 64 66 6c 61 72 65 2c 20 49 6e 63 2e 31 20 30 1e 06 03 55 04 03 13 17 43 6c 6f 75 64 66 6c 61 72 65 20 49 6e 63 20 45 43 43 20 43 41 2d 33 30 1e 17 0d 32 30 30 37 32 39 30 30 30 30 30 30 5a 17 0d 32 31 30 37 32 39 31 32 30 30 30 30 5a 30 6d 31 0b 30 09 06 03 55 04 06 13 02 55 53 31 0b 30 09 06 03 55 04 08 13 02 43 41 31 16 30 14 06 03 55 04 07 13 0d 53 61 6e 20 46 72 61 6e 63 69 73 63 6f 31 19 30 17 06 03 55 04 0a 13 10 43 6c 6f 75 64 66 6c 61 72 65 2c 20 49 6e 63 2e 31 1e 30 1c 06 03 55 04 03 13 15 73 6e 69 2e 63 6c 6f 75 64 66 6c 61 72 65 73 73 6c 2e 63 6f 6d 30 59 30 13 06 07 2a 86 48 ce 3d 02 01 06 08 2a 86 48 ce 3d 03 01 07 03 42 00 04 96 3e cd d8 4d cd 1b 93 a1 cf 43 2d 1a 72 17 d6 c6 3b de 33 55 a0 2f 8c fb 5a d8 99 4c d4 4e 20 5f 15 f6 e3 d2 3b 38 2b a6 49 9b b1 7f 34 1f a5 92 fa 21 86 1f 16 d3 12 06 63 24 05 fd 70 42 bd a3 82 02 fd 30 82 02 f9 30 1f 06 03 55 1d 23 04 18 30 16 80 14 a5 ce 37 ea eb b0 75 0e 94 67 88 b4 45 fa d9 24 10 87 96 1f 30 1d 06 03 55 1d 0e 04 16 04 14 cc 0b 50 e7 d8 37 db f2 43 f3 85 3d 48 60 f5 3b 39 be 9b 2a 30 2e 06 03 55 1d 11 04 27 30 25 82 15 73 6e 69 2e 63 6c 6f 75 64 66 6c 61 72 65 73 73 6c 2e 63 6f 6d 82 0c 77 77 77 2e 69 65 74 66 2e 6f 72 67 30 0e 06 03 55 1d 0f 01 01 ff 04 04 03 02 07 80 30 1d 06 03 55 1d 25 04 16 30 14 06 08 2b 06 01 05 05 07 03 01 06 08 2b 06 01 05 05 07 03 02 30 7b 06 03 55 1d 1f 04 74 30 72 30 37 a0 35 a0 33 86 31 68 74 74 70 3a 2f 2f 63 72 6c 33 2e 64 69 67 69 63 65 72 74 2e 63 6f 6d 2f 43 6c 6f 75 64 66 6c 61 72 65 49 6e 63 45 43 43 43 41 2d 33 2e 63 72 6c 30 37 a0 35 a0 33 86 31 68 74 74 70 3a 2f 2f 63 72 6c 34 2e 64 69 67 69 63 65 72 74 2e 63 6f 6d 2f 43 6c 6f 75 64 66 6c 61 72 65 49 6e 63 45 43 43 43 41 2d 33 2e 63 72 6c 30 4c 06 03 55 1d 20 04 45 30 43 30 37 06 09 60 86 48 01 86 fd 6c Preuß Mattsson, et al. Expires 12 November 2026 [Page 88] Internet-Draft C509 Certificates May 2026 01 01 30 2a 30 28 06 08 2b 06 01 05 05 07 02 01 16 1c 68 74 74 70 73 3a 2f 2f 77 77 77 2e 64 69 67 69 63 65 72 74 2e 63 6f 6d 2f 43 50 53 30 08 06 06 67 81 0c 01 02 02 30 76 06 08 2b 06 01 05 05 07 01 01 04 6a 30 68 30 24 06 08 2b 06 01 05 05 07 30 01 86 18 68 74 74 70 3a 2f 2f 6f 63 73 70 2e 64 69 67 69 63 65 72 74 2e 63 6f 6d 30 40 06 08 2b 06 01 05 05 07 30 02 86 34 68 74 74 70 3a 2f 2f 63 61 63 65 72 74 73 2e 64 69 67 69 63 65 72 74 2e 63 6f 6d 2f 43 6c 6f 75 64 66 6c 61 72 65 49 6e 63 45 43 43 43 41 2d 33 2e 63 72 74 30 0c 06 03 55 1d 13 01 01 ff 04 02 30 00 30 82 01 05 06 0a 2b 06 01 04 01 d6 79 02 04 02 04 81 f6 04 81 f3 00 f1 00 76 00 f6 5c 94 2f d1 77 30 22 14 54 18 08 30 94 56 8e e3 4d 13 19 33 bf df 0c 2f 20 0b cc 4e f1 64 e3 00 00 01 73 9c 83 5f 8e 00 00 04 03 00 47 30 45 02 21 00 f8 d1 b4 a9 3d 2f 0d 4c 41 76 df b4 88 bc c7 3b 86 44 3d 7d e0 0e 6a c8 17 4d 89 48 a8 84 36 68 02 20 29 ff 5a 34 06 8a 24 0c 69 50 27 88 e8 ee 25 ab 7e d2 cb cf 68 6e ce 7b 5f 96 b4 31 a9 07 02 fa 00 77 00 5c dc 43 92 fe e6 ab 45 44 b1 5e 9a d4 56 e6 10 37 fb d5 fa 47 dc a1 73 94 b2 5e e6 f6 c7 0e ca 00 00 01 73 9c 83 5f be 00 00 04 03 00 48 30 46 02 21 00 e8 91 c1 97 bf b0 e3 d3 0c b6 ce e6 0d 94 c3 c7 5f d1 17 53 36 93 11 08 d8 98 12 d4 d2 9d 81 d0 02 21 00 a1 59 d1 6c 46 47 d1 48 37 57 fc d6 ce 4e 75 ec 7b 5e f6 57 ef e0 28 f8 e5 cc 47 92 68 2d ac 43 30 0a 06 08 2a 86 48 ce 3d 04 03 02 03 49 00 30 46 02 21 00 bd 63 cf 4f 7e 5c fe 6c 29 38 5e a7 1c fb fc 1e 3f 7b 1c d0 72 51 a2 21 f7 77 69 c0 f4 71 df ea 02 21 00 b5 c0 6c c4 58 54 fa 30 b2 82 88 b1 d3 bb 9a 66 61 ed 50 31 72 5b 1a 82 02 e0 da 5b 59 f9 54 02 A.3.1. Example: C509 Certificate Encoding The CBOR encoding (~C509Certificate) of the first X.509 certificate is shown below in CBOR diagnostic format. /This defines a CBOR Sequence (RFC 8742):/ 3, h'047FA1E31928EE403BA0B83A395673FC', 0, [ -4, "US", -8, "Cloudflare, Inc.", -1, "Cloudflare Inc ECC CA-3" ], 1595980800, 1627560000, [ -4, "US", -6, "CA", -5, "San Francisco", -8, "Cloudflare, Inc.", -1, "sni.cloudflaressl.com" Preuß Mattsson, et al. Expires 12 November 2026 [Page 89] Internet-Draft C509 Certificates May 2026 ], 1, h'FD963ECDD84DCD1B93A1CF432D1A7217D6C63BDE3355A02F8CFB5AD8994CD44E 20', [ 7, h'A5CE37EAEBB0750E946788B445FAD9241087961F', 1, h'CC0B50E7D837DBF243F3853D4860F53B39BE9B2A', 3, [2, "sni.cloudflaressl.com", 2, "www.ietf.org"], -2, 1, 8, [1, 2], 5, [ ["http://crl3.digicert.com/CloudflareIncECCCA-3.crl", null, null], ["http://crl4.digicert.com/CloudflareIncECCCA-3.crl", null, null] ], 6, [h'6086480186FD6C0101', [1, "https://www.digicert.com/CPS"], 2, []], 9, [1, "http://ocsp.digicert.com", 2, "http://cacerts.digicert.com/CloudflareIncECCCA-3.crt"], -4, -2, h'2B06010401D679020402', h'0481F300F1007600F65C942FD1773022145418083094568EE34D131933BFDF0C 2F200BCC4EF164E3000001739C835F8E0000040300473045022100F8D1B4A93D 2F0D4C4176DFB488BCC73B86443D7DE00E6AC8174D8948A8843668022029FF5A 34068A240C69502788E8EE25AB7ED2CBCF686ECE7B5F96B431A90702FA007700 5CDC4392FEE6AB4544B15E9AD456E61037FBD5FA47DCA17394B25EE6F6C70ECA 000001739C835FBE0000040300483046022100E891C197BFB0E3D30CB6CEE60D 94C3C75FD1175336931108D89812D4D29D81D0022100A159D16C4647D1483757 FCD6CE4E75EC7B5EF657EFE028F8E5CC4792682DAC43' ], h'BD63CF4F7E5CFE6C29385EA71CFBFC1E3F7B1CD07251A221F77769C0F471DFEA B5C06CC45854FA30B28288B1D3BB9A6661ED5031725B1A8202E0DA5B59F95402' The size of the CBOR encoding (CBOR sequence) is 835 bytes. A.4. Example: CAB Baseline RSA HTTPS X.509 Certificate The tools.ietf.org HTTPS server replies with a certificate message with 4 certificates. The DER encoding of the first certificate is 1647 bytes. 30 82 06 6b 30 82 05 53 a0 03 02 01 02 02 09 00 a6 a5 5c 87 0e 39 b4 0e 30 0d 06 09 2a 86 48 86 f7 0d 01 01 0b 05 00 30 81 c6 31 0b 30 09 06 03 55 04 06 13 02 55 53 31 10 30 0e 06 03 55 04 08 13 07 41 72 69 7a 6f 6e 61 31 13 30 11 06 03 55 04 07 13 0a 53 63 6f 74 74 73 64 61 6c 65 31 25 30 23 06 03 55 04 0a 13 1c 53 74 61 72 66 69 65 6c 64 20 54 65 63 68 6e 6f 6c 6f 67 69 65 73 2c 20 49 6e 63 2e 31 33 30 31 06 Preuß Mattsson, et al. Expires 12 November 2026 [Page 90] Internet-Draft C509 Certificates May 2026 03 55 04 0b 13 2a 68 74 74 70 3a 2f 2f 63 65 72 74 73 2e 73 74 61 72 66 69 65 6c 64 74 65 63 68 2e 63 6f 6d 2f 72 65 70 6f 73 69 74 6f 72 79 2f 31 34 30 32 06 03 55 04 03 13 2b 53 74 61 72 66 69 65 6c 64 20 53 65 63 75 72 65 20 43 65 72 74 69 66 69 63 61 74 65 20 41 75 74 68 6f 72 69 74 79 20 2d 20 47 32 30 1e 17 0d 32 30 31 30 30 31 31 39 33 38 33 36 5a 17 0d 32 31 31 31 30 32 31 39 33 38 33 36 5a 30 3e 31 21 30 1f 06 03 55 04 0b 13 18 44 6f 6d 61 69 6e 20 43 6f 6e 74 72 6f 6c 20 56 61 6c 69 64 61 74 65 64 31 19 30 17 06 03 55 04 03 0c 10 2a 2e 74 6f 6f 6c 73 2e 69 65 74 66 2e 6f 72 67 30 82 01 22 30 0d 06 09 2a 86 48 86 f7 0d 01 01 01 05 00 03 82 01 0f 00 30 82 01 0a 02 82 01 01 00 b1 e1 37 e8 eb 82 d6 89 fa db f5 c2 4b 77 f0 2c 4a de 72 6e 3e 13 60 d1 a8 66 1e c4 ad 3d 32 60 e5 f0 99 b5 f4 7a 7a 48 55 21 ee 0e 39 12 f9 ce 0d ca f5 69 61 c7 04 ed 6e 0f 1d 3b 1e 50 88 79 3a 0e 31 41 16 f1 b1 02 64 68 a5 cd f5 4a 0a ca 99 96 35 08 c3 7e 27 5d d0 a9 cf f3 e7 28 af 37 d8 b6 7b dd f3 7e ae 6e 97 7f f7 ca 69 4e cc d0 06 df 5d 27 9b 3b 12 e7 e6 fe 08 6b 52 7b 82 11 7c 72 b3 46 eb c1 e8 78 b8 0f cb e1 eb bd 06 44 58 dc 83 50 b2 a0 62 5b dc 81 b8 36 e3 9e 7c 79 b2 a9 53 8a e0 0b c9 4a 2a 13 39 31 13 bd 2c cf a8 70 cf 8c 8d 3d 01 a3 88 ae 12 00 36 1d 1e 24 2b dd 79 d8 53 01 26 ed 28 4f c9 86 94 83 4e c8 e1 14 2e 85 b3 af d4 6e dd 69 46 af 41 25 0e 7a ad 8b f2 92 ca 79 d9 7b 32 4f f7 77 e8 f9 b4 4f 23 5c d4 5c 03 ae d8 ab 3a ca 13 5f 5d 5d 5d a1 02 03 01 00 01 a3 82 02 e1 30 82 02 dd 30 0c 06 03 55 1d 13 01 01 ff 04 02 30 00 30 1d 06 03 55 1d 25 04 16 30 14 06 08 2b 06 01 05 05 07 03 01 06 08 2b 06 01 05 05 07 03 02 30 0e 06 03 55 1d 0f 01 01 ff 04 04 03 02 05 a0 30 3d 06 03 55 1d 1f 04 36 30 34 30 32 a0 30 a0 2e 86 2c 68 74 74 70 3a 2f 2f 63 72 6c 2e 73 74 61 72 66 69 65 6c 64 74 65 63 68 2e 63 6f 6d 2f 73 66 69 67 32 73 31 2d 32 34 32 2e 63 72 6c 30 63 06 03 55 1d 20 04 5c 30 5a 30 4e 06 0b 60 86 48 01 86 fd 6e 01 07 17 01 30 3f 30 3d 06 08 2b 06 01 05 05 07 02 01 16 31 68 74 74 70 3a 2f 2f 63 65 72 74 69 66 69 63 61 74 65 73 2e 73 74 61 72 66 69 65 6c 64 74 65 63 68 2e 63 6f 6d 2f 72 65 70 6f 73 69 74 6f 72 79 2f 30 08 06 06 67 81 0c 01 02 01 30 81 82 06 08 2b 06 01 05 05 07 01 01 04 76 30 74 30 2a 06 08 2b 06 01 05 05 07 30 01 86 1e 68 74 74 70 3a 2f 2f 6f 63 73 70 2e 73 74 61 72 66 69 65 6c 64 74 65 63 68 2e 63 6f 6d 2f 30 46 06 08 2b 06 01 05 05 07 30 02 86 3a 68 74 74 70 3a 2f 2f 63 65 72 74 69 66 69 63 61 74 65 73 2e 73 74 61 72 66 69 65 6c 64 74 65 63 68 2e 63 6f 6d 2f 72 65 70 6f 73 69 74 6f 72 79 2f 73 66 69 67 32 2e 63 72 74 30 1f 06 03 55 1d 23 04 18 30 16 80 14 25 45 81 68 50 26 38 3d 3b 2d 2c be cd 6a d9 b6 3d b3 66 63 30 2b 06 03 55 1d 11 04 24 30 22 82 10 2a 2e 74 6f 6f 6c 73 2e 69 65 74 66 2e 6f 72 67 82 0e 74 6f 6f 6c 73 2e 69 65 74 66 2e 6f 72 67 30 1d 06 03 55 1d 0e 04 16 04 14 ad 8a b4 1c 07 51 d7 92 89 07 b0 b7 84 62 2f 36 55 7a 5f 4d 30 82 01 06 06 0a 2b 06 01 04 01 d6 79 02 04 02 04 81 f7 04 81 f4 00 f2 00 77 00 f6 5c 94 2f d1 77 30 22 14 54 18 08 30 94 56 8e e3 4d 13 19 33 bf df 0c 2f 20 0b cc 4e f1 64 e3 00 00 01 74 e5 ac 71 13 00 00 04 03 00 48 30 46 02 21 00 8c f5 48 52 ce 56 35 43 39 11 cf 10 cd b9 1f 52 b3 36 39 22 3a d1 38 a4 1d ec a6 fe de 1f e9 0f 02 21 00 bc a2 25 43 66 c1 9a 26 91 c4 7a 00 b5 b6 53 ab bd 44 c2 f8 ba ae f4 d2 Preuß Mattsson, et al. Expires 12 November 2026 [Page 91] Internet-Draft C509 Certificates May 2026 da f2 52 7c e6 45 49 95 00 77 00 5c dc 43 92 fe e6 ab 45 44 b1 5e 9a d4 56 e6 10 37 fb d5 fa 47 dc a1 73 94 b2 5e e6 f6 c7 0e ca 00 00 01 74 e5 ac 72 3c 00 00 04 03 00 48 30 46 02 21 00 a5 e0 90 6e 63 e9 1d 4f dd ef ff 03 52 b9 1e 50 89 60 07 56 4b 44 8a 38 28 f5 96 dc 6b 28 72 6d 02 21 00 fc 91 ea ed 02 16 88 66 05 4e e1 8a 2e 53 46 c4 cc 51 fe b3 fa 10 a9 1d 2e db f9 91 25 f8 6c e6 30 0d 06 09 2a 86 48 86 f7 0d 01 01 0b 05 00 03 82 01 01 00 14 04 3f a0 be d2 ee 3f a8 6e 3a 1f 78 8e a0 4c 35 53 0f 11 06 1f ff 60 a1 6d 0b 83 e9 d9 2a db b3 3f 9d b3 d7 e0 59 4c 19 a8 e4 19 a5 0c a7 70 72 77 63 d5 fe 64 51 0a d2 7a d6 50 a5 8a 92 38 ec cb 2f 0f 5a c0 64 58 4d 5c 06 b9 73 63 68 27 8b 89 34 dc 79 c7 1d 3a fd 34 5f 83 14 41 58 49 80 68 29 80 39 8a 86 72 69 cc 79 37 ce e3 97 f7 dc f3 95 88 ed 81 03 29 00 d2 a2 c7 ba ab d6 3a 8e ca 09 0b d9 fb 39 26 4b ff 03 d8 8e 2d 3f 6b 21 ca 8a 7d d8 5f fb 94 ba 83 de 9c fc 15 8d 61 fa 67 2d b0 c7 db 3d 25 0a 41 4a 85 d3 7f 49 46 37 3c f4 b1 75 d0 52 f3 dd c7 66 f1 4b fd aa 00 ed bf e4 7e ed 01 ec 7b e4 f6 46 fc 31 fd 72 fe 03 d2 f2 65 af 4d 7e e2 81 9b 7a fd 30 3c f5 52 f4 05 34 a0 8a 3e 19 41 58 c8 a8 e0 51 71 84 09 15 ae ec a5 77 75 fa 18 f7 d5 77 d5 31 cc c7 2d A.4.1. Example: C509 Certificate Encoding The CBOR encoding (~C509Certificate) of the first X.509 certificate is shown below in CBOR diagnostic format. /This defines a CBOR Sequence (RFC 8742):/ 3, h'A6A55C870E39B40E', 23, [ -4, "US", -6, "Arizona", -5, "Scottsdale", -8, "Starfield Technologies, Inc.", -9, "http://certs.starfieldtech.com/repository/", -1, "Starfield Secure Certificate Authority - G2" ], 1601581116, 1635881916, [ -9, "Domain Control Validated", 1, "*.tools.ietf.org" ], 0, h'B1E137E8EB82D689FADBF5C24B77F02C4ADE726E3E1360D1A8661EC4AD3D3260 E5F099B5F47A7A485521EE0E3912F9CE0DCAF56961C704ED6E0F1D3B1E508879 3A0E314116F1B1026468A5CDF54A0ACA99963508C37E275DD0A9CFF3E728AF37 D8B67BDDF37EAE6E977FF7CA694ECCD006DF5D279B3B12E7E6FE086B527B8211 Preuß Mattsson, et al. Expires 12 November 2026 [Page 92] Internet-Draft C509 Certificates May 2026 7C72B346EBC1E878B80FCBE1EBBD064458DC8350B2A0625BDC81B836E39E7C79 B2A9538AE00BC94A2A13393113BD2CCFA870CF8C8D3D01A388AE1200361D1E24 2BDD79D8530126ED284FC98694834EC8E1142E85B3AFD46EDD6946AF41250E7A AD8BF292CA79D97B324FF777E8F9B44F235CD45C03AED8AB3ACA135F5D5D5DA1', [ -4, -2, 8, [ 1, 2 ], -2, 5, 5, "http://crl.starfieldtech.com/sfig2s1-242.crl", 6, [ h'6086480186FD6E01071701', [1, "http://certificates.starfieldtech.com/repository/"], 1, [] ], 9, [ 1, "http://ocsp.starfieldtech.com/", 2, "http://certificates.starfieldtech.com/repository/sfig2.crt"], 7, h'254581685026383D3B2D2CBECD6AD9B63DB36663', 3, [ 2, "*.tools.ietf.org", 2, "tools.ietf.org" ], 1, h'AD8AB41C0751D7928907B0B784622F36557A5F4D', h'2B06010401D679020402', h'0481F400F2007700F65C942FD1773022145418083094568EE34D131933BFDF0C 2F200BCC4EF164E300000174E5AC711300000403004830460221008CF54852CE 5635433911CF10CDB91F52B33639223AD138A41DECA6FEDE1FE90F022100BCA2 254366C19A2691C47A00B5B653ABBD44C2F8BAAEF4D2DAF2527CE64549950077 005CDC4392FEE6AB4544B15E9AD456E61037FBD5FA47DCA17394B25EE6F6C70E CA00000174E5AC723C0000040300483046022100A5E0906E63E91D4FDDEFFF03 52B91E50896007564B448A3828F596DC6B28726D022100FC91EAED0216886605 4EE18A2E5346C4CC51FEB3FA10A91D2EDBF99125F86CE6' ], h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he size of the CBOR encoding (CBOR sequence) is 1295 bytes. A.5. Example: Certificate with Extensions IPAddrBlocks and IPAddrBlocksV2 An example X.509 certificate with extensions IPAddrBlocks and IPAddrBlocksV2. Preuß Mattsson, et al. Expires 12 November 2026 [Page 93] Internet-Draft C509 Certificates May 2026 Certificate: Version: v3 (2) Serial Number: 12:34 Issuer: CN=selfsign-brainpoolp384r1,SURNAME=my surname,T=my title, GIVENNAME=my givenName,Name=my name Validity: Not Before: Thu Jan 02 01:00:00 CET 2025 Not After : Fri Jan 02 01:00:00 CET 2026 Subject: CN=selfsign-brainpoolp384r1,SURNAME=my surname,T=my title ,GIVENNAME=my givenName,Name=my name Subject Public Key Info: Public Key Algorithm: EC/BRAINPOOLP384R1 Pub: 04:67:09:c9:92:91:9b:49:c4:8f:d9:31:d0:5c:49:7d:38:65: e6:08:4c:91:df:3a:4c:7e:78:1f:41:85:43:b0:23:d5:9e:8b: f2:5d:13:3f:b1:a0:94:e9:d4:2c:8f:a6:ed:3b:46:e9:88:3a: 35:ab:d4:b0:a9:d3:0a:ae:fd:9b:7e:88:ed:38:00:56:5d:1e: 7f:06:33:13:4d:65:19:29:2d:49:bd:55:ec:30:a1:67:19:7f: ec:0f:74:29:82:2b:95 X509v3 extensions: X509v3 keyUsage: digitalSignature X509v3 sbgp-ipAddrBlock: IPv4: 192.0.2.0/24 198.51.100.0/28 203.0.113.0/24 IPv6: 2001:db8:1234::/48 3fff:600:: - 3fff:fff:ffff:ffff:ffff:ffff:ffff:ffff X509v3 sbgp-ipAddrBlockV2: IPv4 unicast: 192.0.2.0/24 198.51.100.0/28 203.0.113.0/24 IPv6 unicast: 2001:db8:1234::/48 3fff:3:: - 3fff:122:0:2233:3344:5566:ffff:ffff Signature Algorithm: SHA384WITHECDSA Signature Value: 30:64:02:30:67:09:c9:92:91:9b:49:c4:8f:d9:31:d0:5c:49: 7d:38:65:e6:08:4c:91:df:3a:4c:7e:78:1f:41:85:43:b0:23: d5:9e:8b:f2:5d:13:3f:b1:a0:94:e9:d4:2c:8f:a6:ed:02:30: 20:ed:9f:db:5a:30:9b:2c:87:04:dd:a5:f1:44:f1:7b:b3:16: b9:8c:29:11:24:fb:a5:cf:ec:6e:f9:7f:26:88:06:9a:e6:c5: 2e:2b:3c:e2:23:12:8d:d1:0c:2a:a7:30 Preuß Mattsson, et al. Expires 12 November 2026 [Page 94] Internet-Draft C509 Certificates May 2026 The DER encoding of the certificate is 717 bytes: 30 82 02 c9 30 82 02 50 a0 03 02 01 02 02 02 12 34 30 0a 06 08 2a 86 48 ce 3d 04 03 03 30 74 31 21 30 1f 06 03 55 04 03 0c 18 73 65 6c 66 73 69 67 6e 2d 62 72 61 69 6e 70 6f 6f 6c 70 33 38 34 72 31 31 13 30 11 06 03 55 04 04 0c 0a 6d 79 20 73 75 72 6e 61 6d 65 31 11 30 0f 06 03 55 04 0c 0c 08 6d 79 20 74 69 74 6c 65 31 15 30 13 06 03 55 04 2a 0c 0c 6d 79 20 67 69 76 65 6e 4e 61 6d 65 31 10 30 0e 06 03 55 04 29 0c 07 6d 79 20 6e 61 6d 65 30 1e 17 0d 32 35 30 31 30 32 30 30 30 30 30 30 5a 17 0d 32 36 30 31 30 32 30 30 30 30 30 30 5a 30 74 31 21 30 1f 06 03 55 04 03 0c 18 73 65 6c 66 73 69 67 6e 2d 62 72 61 69 6e 70 6f 6f 6c 70 33 38 34 72 31 31 13 30 11 06 03 55 04 04 0c 0a 6d 79 20 73 75 72 6e 61 6d 65 31 11 30 0f 06 03 55 04 0c 0c 08 6d 79 20 74 69 74 6c 65 31 15 30 13 06 03 55 04 2a 0c 0c 6d 79 20 67 69 76 65 6e 4e 61 6d 65 31 10 30 0e 06 03 55 04 29 0c 07 6d 79 20 6e 61 6d 65 30 7a 30 14 06 07 2a 86 48 ce 3d 02 01 06 09 2b 24 03 03 02 08 01 01 0b 03 62 00 04 67 09 c9 92 91 9b 49 c4 8f d9 31 d0 5c 49 7d 38 65 e6 08 4c 91 df 3a 4c 7e 78 1f 41 85 43 b0 23 d5 9e 8b f2 5d 13 3f b1 a0 94 e9 d4 2c 8f a6 ed 3b 46 e9 88 3a 35 ab d4 b0 a9 d3 0a ae fd 9b 7e 88 ed 38 00 56 5d 1e 7f 06 33 13 4d 65 19 29 2d 49 bd 55 ec 30 a1 67 19 7f ec 0f 74 29 82 2b 95 a3 81 b0 30 81 ad 30 0b 06 03 55 1d 0f 04 04 03 02 07 80 30 48 06 08 2b 06 01 05 05 07 01 07 04 3c 30 3a 30 19 04 02 00 01 30 13 03 04 00 c0 00 02 03 05 04 c6 33 64 00 03 04 00 cb 00 71 30 1d 04 02 00 02 30 17 03 07 00 20 01 0d b8 12 34 30 0c 03 04 00 3f ff 06 03 04 00 3f ff 0f 30 54 06 08 2b 06 01 05 05 07 01 1c 04 48 30 46 30 1a 04 03 00 01 01 30 13 03 04 00 c0 00 02 03 05 04 c6 33 64 00 03 04 00 cb 00 71 30 28 04 03 00 02 01 30 21 03 07 00 20 01 0d b8 12 34 30 16 03 05 00 3f ff 00 03 03 0d 00 3f ff 01 22 00 00 22 33 33 44 55 66 30 0a 06 08 2a 86 48 ce 3d 04 03 03 03 67 00 30 64 02 30 67 09 c9 92 91 9b 49 c4 8f d9 31 d0 5c 49 7d 38 65 e6 08 4c 91 df 3a 4c 7e 78 1f 41 85 43 b0 23 d5 9e 8b f2 5d 13 3f b1 a0 94 e9 d4 2c 8f a6 ed 02 30 20 ed 9f db 5a 30 9b 2c 87 04 dd a5 f1 44 f1 7b b3 16 b9 8c 29 11 24 fb a5 cf ec 6e f9 7f 26 88 06 9a e6 c5 2e 2b 3c e2 23 12 8d d1 0c 2a a7 30 A.5.1. Example: C509 Certificate Encoding The CBOR encoding (~C509Certificate) of the X.509 certificate is shown below in CBOR diagnostic format. Preuß Mattsson, et al. Expires 12 November 2026 [Page 95] Internet-Draft C509 Certificates May 2026 /This defines a CBOR Sequence (RFC 8742):/ 3, h'1234', 1, null, 1735776000, 1767312000, [ 1,"selfsign-brainpoolp384r1", 2, "my surname", 10, "my title", 13, "my givenName", 25, "my name" ], 25, h'046709C992919B49C48FD931D05C497D3865E6084C91DF3A4C7E781F418543B0 23D59E8BF25D133FB1A094E9D42C8FA6ED3B46E9883A35ABD4B0A9D30AAEFD9B 7E88ED3800565D1E7F0633134D6519292D49BD55EC30A167197FEC0F7429822B 95', [ 2, 1, 32, [ 1, null, [ 29360130, 24770733054, -24770012047 ], 2, null, [ 316663873933876, [ -316663852962606, 9 ] ] ], 34, [ 1, 1, [ 29360130, 24770733054, -24770012047 ], 2, 1, [ h'0020010DB81234', [ h'003FFF0003', h'003FFF01220000223333445566' ] ] ] ], h'6709C992919B49C48FD931D05C497D3865E6084C91DF3A4C7E781F418543B023 D59E8BF25D133FB1A094E9D42C8FA6ED20ED9FDB5A309B2C8704DDA5F144F17B B316B98C291124FBA5CFEC6EF97F2688069AE6C52E2B3CE223128DD10C2AA730' Preuß Mattsson, et al. Expires 12 November 2026 [Page 96] Internet-Draft C509 Certificates May 2026 Acknowledgments The authors want to thank Henk Birkholz, Mike Bishop, Mohamed Boucadair, Corey Bonnell, Carsten Bormann, Deb Cooley, Roman Danyliw, Viktor Dukhovni, Paul Hoffman, Russ Housley, Christopher Inacio, Olle Johansson, Benjamin Kaduk, Ted Lemon, Ilari Liusvaara, Laurence Lundblade, Francesca Palombini, Thomas Peterson, Michael Richardson, Stefan Santesson, Jim Schaad, Brian Sipos, Rene Struik, Ketan Talaulikar, Fraser Tweedale, Gunter Van de Velde, Éric Vyncke, and Paul Wouters for reviewing and commenting on intermediate versions of the draft. Authors' Addresses John Preuß Mattsson Ericsson AB Email: john.mattsson@ericsson.com Göran Selander Ericsson AB Email: goran.selander@ericsson.com Shahid Raza University of Glasgow Email: shahid.raza@glasgow.ac.uk Joel Höglund RISE AB Email: joel.hoglund@ri.se Martin Furuhed IN Groupe Email: martin.furuhed@ingroupe.com Lijun Liao NIO Email: lijun.liao@nio.io Preuß Mattsson, et al. Expires 12 November 2026 [Page 97]