=encoding utf8

=head1 NAME

Mail::Message::Field::DKIM - message header field for dkim signatures

=head1 INHERITANCE

 Mail::Message::Field::DKIM
   is a Mail::Message::Field::Structured
   is a Mail::Message::Field::Full
   is a Mail::Message::Field
   is a Mail::Reporter

=head1 SYNOPSIS

 my $f = Mail::Message::Field->new('DKIM-Signature' => '...');

 my $g = Mail::Message::Field->new('DKIM-Signature');
 $g->add...

=head1 DESCRIPTION

Decode the information contained in a DKIM header.  You can also
construct DKIM-Signature headers this way.  However, verification
and signing is not yet implemented.

This implementation is based on RFC6376.

Extends L<"DESCRIPTION" in Mail::Message::Field::Structured|Mail::Message::Field::Structured/"DESCRIPTION">.
 
=head1 OVERLOADED

Extends L<"OVERLOADED" in Mail::Message::Field::Structured|Mail::Message::Field::Structured/"OVERLOADED">.
 
=over 4

=item overload: B<"">

Inherited, see L<Mail::Message::Field/"OVERLOADED">

=item overload: B<0+>

Inherited, see L<Mail::Message::Field/"OVERLOADED">

=item overload: B<<=>>

Inherited, see L<Mail::Message::Field/"OVERLOADED">

=item overload: B<bool>

Inherited, see L<Mail::Message::Field/"OVERLOADED">

=item overload: B<cmp>

Inherited, see L<Mail::Message::Field/"OVERLOADED">

=item overload: B<stringification>

Inherited, see L<Mail::Message::Field::Full/"OVERLOADED">

=back

=head1 METHODS

Extends L<"METHODS" in Mail::Message::Field::Structured|Mail::Message::Field::Structured/"METHODS">.
 
=head2 Constructors

Extends L<"Constructors" in Mail::Message::Field::Structured|Mail::Message::Field::Structured/"Constructors">.
 
=over 4

=item $obj-E<gt>B<clone>()

Inherited, see L<Mail::Message::Field/"Constructors">

=item Mail::Message::Field::DKIM-E<gt>B<from>($field, %options)

Inherited, see L<Mail::Message::Field::Full/"Constructors">

=item Mail::Message::Field::DKIM-E<gt>B<new>($data)

 -Option    --Defined in                      --Default
  attributes  Mail::Message::Field::Structured  <ignored>
  charset     Mail::Message::Field::Full        undef
  datum       Mail::Message::Field::Structured  undef
  encoding    Mail::Message::Field::Full        'q'
  force       Mail::Message::Field::Full        false
  language    Mail::Message::Field::Full        undef
  log         Mail::Reporter                    'WARNINGS'
  trace       Mail::Reporter                    'WARNINGS'

=over 2

=item attributes => ATTRS

=item charset => STRING

=item datum => STRING

=item encoding => 'q'|'Q'|'b'|'B'

=item force => BOOLEAN

=item language => STRING

=item log => LEVEL

=item trace => LEVEL

=back

=back

=head2 The field

Extends L<"The field" in Mail::Message::Field::Structured|Mail::Message::Field::Structured/"The field">.
 
=over 4

=item $obj-E<gt>B<isStructured>()

=item Mail::Message::Field::DKIM-E<gt>B<isStructured>()

Inherited, see L<Mail::Message::Field/"The field">

=item $obj-E<gt>B<length>()

Inherited, see L<Mail::Message::Field/"The field">

=item $obj-E<gt>B<nrLines>()

Inherited, see L<Mail::Message::Field/"The field">

=item $obj-E<gt>B<print>( [$fh] )

Inherited, see L<Mail::Message::Field/"The field">

=item $obj-E<gt>B<size>()

Inherited, see L<Mail::Message::Field/"The field">

=item $obj-E<gt>B<string>( [$wrap] )

Inherited, see L<Mail::Message::Field/"The field">

=item $obj-E<gt>B<toDisclose>()

Inherited, see L<Mail::Message::Field/"The field">

=back

=head2 Access to the name

Extends L<"Access to the name" in Mail::Message::Field::Structured|Mail::Message::Field::Structured/"Access to the name">.
 
=over 4

=item $obj-E<gt>B<Name>()

Inherited, see L<Mail::Message::Field/"Access to the name">

=item $obj-E<gt>B<name>()

Inherited, see L<Mail::Message::Field/"Access to the name">

=item $obj-E<gt>B<wellformedName>( [STRING] )

Inherited, see L<Mail::Message::Field/"Access to the name">

=back

=head2 Access to the body

Extends L<"Access to the body" in Mail::Message::Field::Structured|Mail::Message::Field::Structured/"Access to the body">.
 
=over 4

=item $obj-E<gt>B<body>()

Inherited, see L<Mail::Message::Field/"Access to the body">

=item $obj-E<gt>B<decodedBody>(%options)

Inherited, see L<Mail::Message::Field::Full/"Access to the body">

=item $obj-E<gt>B<folded>()

Inherited, see L<Mail::Message::Field/"Access to the body">

=item $obj-E<gt>B<foldedBody>( [$body] )

Inherited, see L<Mail::Message::Field/"Access to the body">

=item $obj-E<gt>B<stripCFWS>( [STRING] )

=item Mail::Message::Field::DKIM-E<gt>B<stripCFWS>( [STRING] )

Inherited, see L<Mail::Message::Field/"Access to the body">

=item $obj-E<gt>B<unfoldedBody>( [$body, [$wrap]] )

Inherited, see L<Mail::Message::Field/"Access to the body">

=back

=head2 Access to the content

Extends L<"Access to the content" in Mail::Message::Field::Structured|Mail::Message::Field::Structured/"Access to the content">.
 
=over 4

=item $obj-E<gt>B<addAttribute>(...)

Attributes are not supported here.

=item $obj-E<gt>B<addTag>($name, $value|@values)

Add a tag to the set.  When the tag already exists, it is replaced.
Names are (converted to) lower-case.  When multiple values are given,
they will be concatenated with a blank (and may get folded there later)

=item $obj-E<gt>B<addresses>()

Inherited, see L<Mail::Message::Field/"Access to the content">

=item $obj-E<gt>B<attrPairs>()

Inherited, see L<Mail::Message::Field::Structured/"Access to the content">

=item $obj-E<gt>B<attribute>( $object|<STRING, %options>|<$name,$value,%options> )

Inherited, see L<Mail::Message::Field::Structured/"Access to the content">

=item $obj-E<gt>B<attributes>()

Inherited, see L<Mail::Message::Field::Structured/"Access to the content">

=item $obj-E<gt>B<beautify>()

Inherited, see L<Mail::Message::Field::Full/"Access to the content">

=item $obj-E<gt>B<comment>( [STRING] )

Inherited, see L<Mail::Message::Field/"Access to the content">

=item $obj-E<gt>B<createComment>(STRING, %options)

=item Mail::Message::Field::DKIM-E<gt>B<createComment>(STRING, %options)

Inherited, see L<Mail::Message::Field::Full/"Access to the content">

=item $obj-E<gt>B<createPhrase>(STRING, %options)

=item Mail::Message::Field::DKIM-E<gt>B<createPhrase>(STRING, %options)

Inherited, see L<Mail::Message::Field::Full/"Access to the content">

=item $obj-E<gt>B<study>()

Inherited, see L<Mail::Message::Field/"Access to the content">

=item $obj-E<gt>B<tag>($name)

Returns the value for the named tag.

=item $obj-E<gt>B<toDate>( [$time] )

=item Mail::Message::Field::DKIM-E<gt>B<toDate>( [$time] )

Inherited, see L<Mail::Message::Field/"Access to the content">

=item $obj-E<gt>B<toInt>()

Inherited, see L<Mail::Message::Field/"Access to the content">

=back

=head3 DKIM-Signature tags

The tag methods return the tag-value content without any validation
or modification.  For many situations, the actual content does not
need (expensive) validation and interpretation.

=over 4

=item $obj-E<gt>B<tagAgentID>()

The Agent or User Identifier (AUID).  Defaults to C<@$domain>

=item $obj-E<gt>B<tagAlgorithm>()

Signature algorithm.  Should be rsa-sha(1|256): check before use. Required.

=item $obj-E<gt>B<tagBodyLength>()

The number of octets which where used to calculate the hash.  By default,
the whole body was used.

=item $obj-E<gt>B<tagC14N>()

The canonicalization method used.  Defaults to 'simple/simple'.

=item $obj-E<gt>B<tagDomain>()

The sub-domain (SDID) which claims responsibility for this signature. Required.

=item $obj-E<gt>B<tagExpires>()

The timestamp when the signature will expire.  Recommended.

=item $obj-E<gt>B<tagExtract>()

Some headers from the original message packed together.

=item $obj-E<gt>B<tagQueryMethods>()

A colon-separated list of method which can be used to retrieve the
public key.  The default is "dns/txt" (currently the only valid option)

=item $obj-E<gt>B<tagSelector>()

The selector subdividing the $domain tag.  Required.

=item $obj-E<gt>B<tagSignData>()

=item $obj-E<gt>B<tagSignature>()

Message signature in base64, with whitespaces removed. Required.

=item $obj-E<gt>B<tagSignedHeaders>()

The colon separated list of headers which need to be included in the
signature.  Required.

=item $obj-E<gt>B<tagTimestamp>()

When the signature was created in UNIX-like seconds (since 1970).  Recommended.

=item $obj-E<gt>B<tagVersion>()

Signature header syntax version (usually 1)

=back

=head2 Other methods

Extends L<"Other methods" in Mail::Message::Field::Structured|Mail::Message::Field::Structured/"Other methods">.
 
=over 4

=item $obj-E<gt>B<dateToTimestamp>(STRING)

=item Mail::Message::Field::DKIM-E<gt>B<dateToTimestamp>(STRING)

Inherited, see L<Mail::Message::Field/"Other methods">

=back

=head2 Internals

Extends L<"Internals" in Mail::Message::Field::Structured|Mail::Message::Field::Structured/"Internals">.
 
=over 4

=item $obj-E<gt>B<consume>( $line | <$name,<$body|$objects>> )

Inherited, see L<Mail::Message::Field/"Internals">

=item $obj-E<gt>B<decode>(STRING, %options)

=item Mail::Message::Field::DKIM-E<gt>B<decode>(STRING, %options)

Inherited, see L<Mail::Message::Field::Full/"Internals">

=item $obj-E<gt>B<defaultWrapLength>( [$length] )

Inherited, see L<Mail::Message::Field/"Internals">

=item $obj-E<gt>B<encode>(STRING, %options)

Inherited, see L<Mail::Message::Field::Full/"Internals">

=item $obj-E<gt>B<fold>( $name, $body, [$maxchars] )

=item Mail::Message::Field::DKIM-E<gt>B<fold>( $name, $body, [$maxchars] )

Inherited, see L<Mail::Message::Field/"Internals">

=item $obj-E<gt>B<setWrapLength>( [$length] )

Inherited, see L<Mail::Message::Field/"Internals">

=item $obj-E<gt>B<stringifyData>(STRING|ARRAY|$objects)

Inherited, see L<Mail::Message::Field/"Internals">

=item $obj-E<gt>B<unfold>(STRING)

Inherited, see L<Mail::Message::Field/"Internals">

=back

=head2 Parsing

Extends L<"Parsing" in Mail::Message::Field::Structured|Mail::Message::Field::Structured/"Parsing">.
 
=over 4

=item $obj-E<gt>B<consumeComment>(STRING)

=item Mail::Message::Field::DKIM-E<gt>B<consumeComment>(STRING)

Inherited, see L<Mail::Message::Field::Full/"Parsing">

=item $obj-E<gt>B<consumeDotAtom>(STRING)

Inherited, see L<Mail::Message::Field::Full/"Parsing">

=item $obj-E<gt>B<consumePhrase>(STRING)

=item Mail::Message::Field::DKIM-E<gt>B<consumePhrase>(STRING)

Inherited, see L<Mail::Message::Field::Full/"Parsing">

=item $obj-E<gt>B<datum>( [$value] )

Inherited, see L<Mail::Message::Field::Structured/"Parsing">

=item $obj-E<gt>B<parse>(STRING)

Inherited, see L<Mail::Message::Field::Full/"Parsing">

=item $obj-E<gt>B<produceBody>()

Inherited, see L<Mail::Message::Field::Full/"Parsing">

=back

=head2 Error handling

Extends L<"Error handling" in Mail::Message::Field::Structured|Mail::Message::Field::Structured/"Error handling">.
 
=over 4

=item $obj-E<gt>B<AUTOLOAD>()

Inherited, see L<Mail::Reporter/"Error handling">

=item $obj-E<gt>B<addReport>($object)

Inherited, see L<Mail::Reporter/"Error handling">

=item $obj-E<gt>B<defaultTrace>( [$level]|[$loglevel, $tracelevel]|[$level, $callback] )

=item Mail::Message::Field::DKIM-E<gt>B<defaultTrace>( [$level]|[$loglevel, $tracelevel]|[$level, $callback] )

Inherited, see L<Mail::Reporter/"Error handling">

=item $obj-E<gt>B<errors>()

Inherited, see L<Mail::Reporter/"Error handling">

=item $obj-E<gt>B<log>( [$level, [$strings]] )

=item Mail::Message::Field::DKIM-E<gt>B<log>( [$level, [$strings]] )

Inherited, see L<Mail::Reporter/"Error handling">

=item $obj-E<gt>B<logPriority>($level)

=item Mail::Message::Field::DKIM-E<gt>B<logPriority>($level)

Inherited, see L<Mail::Reporter/"Error handling">

=item $obj-E<gt>B<logSettings>()

Inherited, see L<Mail::Reporter/"Error handling">

=item $obj-E<gt>B<notImplemented>()

Inherited, see L<Mail::Reporter/"Error handling">

=item $obj-E<gt>B<report>( [$level] )

Inherited, see L<Mail::Reporter/"Error handling">

=item $obj-E<gt>B<reportAll>( [$level] )

Inherited, see L<Mail::Reporter/"Error handling">

=item $obj-E<gt>B<trace>( [$level] )

Inherited, see L<Mail::Reporter/"Error handling">

=item $obj-E<gt>B<warnings>()

Inherited, see L<Mail::Reporter/"Error handling">

=back

=head2 Cleanup

Extends L<"Cleanup" in Mail::Message::Field::Structured|Mail::Message::Field::Structured/"Cleanup">.
 
=over 4

=item $obj-E<gt>B<DESTROY>()

Inherited, see L<Mail::Reporter/"Cleanup">

=back

=head1 DETAILS

Extends L<"DETAILS" in Mail::Message::Field::Structured|Mail::Message::Field::Structured/"DETAILS">.
 
=head1 DIAGNOSTICS

=over 4

=item Warning: Field content is not numerical: $content

The numeric value of a field is requested (for instance the C<Lines> or
C<Content-Length> fields should be numerical), however the data contains
weird characters.

=item Error: Field name too long (max $length), in '$name'

It is not specified in the RFCs how long a field name can be, but
at least it should be a few characters shorter than the line wrap.

=item Warning: Illegal character in charset '$charset'

The field is created with an utf8 string which only contains data from the
specified character set.  However, that character set can never be a valid
name because it contains characters which are not permitted.

=item Warning: Illegal character in field name $name

A new field is being created which does contain characters not permitted
by the RFCs.  Using this field in messages may break other e-mail clients
or transfer agents, and therefore mutulate or extinguish your message.

=item Warning: Illegal character in language '$lang'

The field is created with data which is specified to be in a certain language,
however, the name of the language cannot be valid: it contains characters
which are not permitted by the RFCs.

=item Warning: Illegal encoding '$encoding', used 'q'

The RFCs only permit base64 (C<b > or C<B >) or quoted-printable
(C<q> or C<Q>) encoding.  Other than these four options are illegal.

=item Error: No attributes for DKIM headers

Is is not possible to add attributes to this field.

=item Error: Package $package does not implement $method.

Fatal error: the specific package (or one of its superclasses) does not
implement this method where it should. This message means that some other
related classes do implement this method however the class at hand does
not.  Probably you should investigate this and probably inform the author
of the package.

=back

=head1 SEE ALSO

This module is part of Mail-Message distribution version 3.017,
built on April 18, 2025. Website: F<http://perl.overmeer.net/CPAN/>

=head1 LICENSE

Copyrights 2001-2025 by [Mark Overmeer <markov@cpan.org>]. For other contributors see ChangeLog.

This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
See F<http://dev.perl.org/licenses/>

