NAME
    Crypt::OpenSSL::RSA - RSA encoding and decoding, using the openSSL
    libraries

SYNOPSIS
      use Crypt::OpenSSL::Random;
      use Crypt::OpenSSL::RSA;

      # not necessary if we have /dev/random:
      Crypt::OpenSSL::Random::random_seed($good_entropy);
      Crypt::OpenSSL::RSA->import_random_seed();
      $rsa_pub = Crypt::OpenSSL::RSA->new_public_key($key_string);
      $ciphertext = $rsa->encrypt($plaintext);

      $rsa_priv = Crypt::OpenSSL::RSA->new_private_key($key_string);
      $plaintext = $rsa->encrypt($ciphertext);

      $rsa = Crypt::OpenSSL::RSA->generate_key(1024); # or
      $rsa = Crypt::OpenSSL::RSA->generate_key(1024, $prime);

      print "private key is:\n", $rsa->get_private_key_string();
      print "public key (in PKCS1 format) is:\n",
            $rsa->get_public_key_string();
      print "public key (in X509 format) is:\n",
            $rsa->get_public_key_x509_string();

      $rsa_priv->use_md5_hash(); # insecure. use_sha256_hash or use_sha1_hash are the default
      $signature = $rsa_priv->sign($plaintext);
      print "Signed correctly\n" if ($rsa->verify($plaintext, $signature));

DESCRIPTION
    "Crypt::OpenSSL::RSA" provides the ability to RSA encrypt strings which
    are somewhat shorter than the block size of a key. It also allows for
    decryption, signatures and signature verification.

    *NOTE*: Many of the methods in this package can croak, so use "eval", or
    Error.pm's try/catch mechanism to capture errors. Also, while some
    methods from earlier versions of this package return true on success,
    this (never documented) behavior is no longer the case.

Class Methods
    new_public_key
        Create a new "Crypt::OpenSSL::RSA" object by loading a public key in
        from a string containing Base64/DER-encoding of either the PKCS1 or
        X.509 representation of the key. The string should include the
        "-----BEGIN...-----" and "-----END...-----" lines.

        The padding is set to PKCS1_OAEP, but can be changed with the
        "use_xxx_padding" methods.

    new_private_key
        Create a new "Crypt::OpenSSL::RSA" object by loading a private key
        in from an string containing the Base64/DER encoding of the PKCS1
        representation of the key. The string should include the
        "-----BEGIN...-----" and "-----END...-----" lines. The padding is
        set to PKCS1_OAEP, but can be changed with "use_xxx_padding".

        An optional parameter can be passed for passphase protected private
        key:

        passphase
            The passphase which protects the private key.

    generate_key
        Create a new "Crypt::OpenSSL::RSA" object by constructing a
        private/public key pair. The first (mandatory) argument is the key
        size, while the second optional argument specifies the public
        exponent (the default public exponent is 65537). The padding is set
        to "PKCS1_OAEP", but can be changed with use_xxx_padding methods.

    new_key_from_parameters
        Given Crypt::OpenSSL::Bignum objects for n, e, and optionally d, p,
        and q, where p and q are the prime factors of n, e is the public
        exponent and d is the private exponent, create a new
        Crypt::OpenSSL::RSA object using these values. If p and q are
        provided and d is undef, d is computed. Note that while p and q are
        not necessary for a private key, their presence will speed up
        computation.

    import_random_seed
        Import a random seed from Crypt::OpenSSL::Random, since the OpenSSL
        libraries won't allow sharing of random structures across perl XS
        modules.

Instance Methods
    DESTROY
        Clean up after ourselves. In particular, erase and free the memory
        occupied by the RSA key structure.

    get_public_key_string
        Return the Base64/DER-encoded PKCS1 representation of the public
        key. This string has header and footer lines:

          -----BEGIN RSA PUBLIC KEY------
          -----END RSA PUBLIC KEY------

    get_public_key_x509_string
        Return the Base64/DER-encoded representation of the "subject public
        key", suitable for use in X509 certificates. This string has header
        and footer lines:

          -----BEGIN PUBLIC KEY------
          -----END PUBLIC KEY------

        and is the format that is produced by running "openssl rsa -pubout".

    get_private_key_string
        Return the Base64/DER-encoded PKCS1 representation of the private
        key. This string has header and footer lines:

          -----BEGIN RSA PRIVATE KEY------
          -----END RSA PRIVATE KEY------

        2 optional parameters can be passed for passphase protected private
        key string:

        passphase
            The passphase which protects the private key.

        cipher name
            The cipher algorithm used to protect the private key. Default to
            'des3'.

    encrypt
        Encrypt a binary "string" using the public (portion of the) key.

    decrypt
        Decrypt a binary "string". Croaks if the key is public only.

    private_encrypt
        Encrypt a binary "string" using the private key. Croaks if the key
        is public only.

    public_decrypt
        Decrypt a binary "string" using the public (portion of the) key.

    sign
        Sign a string using the secret (portion of the) key.

    verify
        Check the signature on a text.

    use_no_padding
        Use raw RSA encryption. This mode should only be used to implement
        cryptographically sound padding modes in the application code.
        Encrypting user data directly with RSA is insecure.

    use_pkcs1_padding
        Use PKCS #1 v1.5 padding. This currently is the most widely used
        mode of padding.

    use_pkcs1_oaep_padding
        Use "EME-OAEP" padding as defined in PKCS #1 v2.0 with SHA-1, MGF1
        and an empty encoding parameter. This mode of padding is recommended
        for all new applications. It is the default mode used by
        "Crypt::OpenSSL::RSA".

    use_sslv23_padding
        Use "PKCS #1 v1.5" padding with an SSL-specific modification that
        denotes that the server is SSL3 capable.

        Not available since OpenSSL 3.

    use_md5_hash
        Use the RFC 1321 MD5 hashing algorithm by Ron Rivest when signing
        and verifying messages.

        Note that this is considered insecure.

    use_sha1_hash
        Use the RFC 3174 Secure Hashing Algorithm (FIPS 180-1) when signing
        and verifying messages. This is the default, when use_sha256_hash is
        not available.

    use_sha224_hash, use_sha256_hash, use_sha384_hash, use_sha512_hash
        These FIPS 180-2 hash algorithms, for use when signing and verifying
        messages, are only available with newer openssl versions (>= 0.9.8).

        use_sha256_hash is the default hash mode when available.

    use_ripemd160_hash
        Dobbertin, Bosselaers and Preneel's RIPEMD hashing algorithm when
        signing and verifying messages.

    use_whirlpool_hash
        Vincent Rijmen und Paulo S. L. M. Barreto ISO/IEC 10118-3:2004
        WHIRLPOOL hashing algorithm when signing and verifying messages.

    size
        Returns the size, in bytes, of the key. All encrypted text will be
        of this size, and depending on the padding mode used, the length of
        the text to be encrypted should be:

        pkcs1_oaep_padding
            at most 42 bytes less than this size.

        pkcs1_padding or sslv23_padding
            at most 11 bytes less than this size.

        no_padding
            exactly this size.

    check_key
        This function validates the RSA key, returning a true value if the
        key is valid, and a false value otherwise. Croaks if the key is
        public only.

    get_key_parameters
        Return "Crypt::OpenSSL::Bignum" objects representing the values of
        "n", "e", "d", "p", "q", "d mod (p-1)", "d mod (q-1)", and "1/q mod
        p", where "p" and "q" are the prime factors of "n", "e" is the
        public exponent and "d" is the private exponent. Some of these
        values may return as "undef"; only "n" and "e" will be defined for a
        public key. The "Crypt::OpenSSL::Bignum" module must be installed
        for this to work.

    is_private
        Return true if this is a private key, and false if it is private
        only.

BUGS
    There is a small memory leak when generating new keys of more than 512
    bits.

AUTHOR
    Ian Robertson, "iroberts@cpan.org". For support, please email
    "perl-openssl-users@lists.sourceforge.net".

ACKNOWLEDGEMENTS
LICENSE
    Copyright (c) 2001-2011 Ian Robertson. Crypt::OpenSSL::RSA is free
    software; you may redistribute it and/or modify it under the same terms
    as Perl itself.

SEE ALSO
    perl(1), Crypt::OpenSSL::Random, Crypt::OpenSSL::Bignum, rsa(3),
    RSA_new(3) <http://man.he.net/?topic=RSA_new&section=3>,
    RSA_public_encrypt(3)
    <http://man.he.net/?topic=RSA_public_encrypt&section=3>, RSA_size(3)
    <http://man.he.net/?topic=RSA_size&section=3>, RSA_generate_key(3)
    <http://man.he.net/?topic=RSA_generate_key&section=3>, RSA_check_key(3)
    <http://man.he.net/?topic=RSA_check_key&section=3>

