---
name: "Mail::DKIM::DkSignature"
section: "3pm"
platform: "linux"
package: "perl-mail-dkim"
version: "1.20240923-3"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/Mail::DKIM::DkSignature"
---

# Mail::DKIM::DkSignature(3pm)

represents a DomainKeys-Signature header

## NAME

Mail::DKIM::DkSignature - represents a DomainKeys-Signature header

## VERSION

version 1.20240923

## CONSTRUCTORS

### new()

Create a new DomainKey signature from parameters

```
  my $signature = Mail::DKIM::DkSignature->new(
                      [ Algorithm => 'rsa-sha1', ]
                      [ Signature => $base64, ]
                      [ Method => 'simple', ]
                      [ Domain => 'example.org', ]
                      [ Headers => 'from:subject:date:message-id', ]
                      [ Query => 'dns', ]
                      [ Selector => 'alpha', ]
                      [ Key => $private_key, ]
                  );
```

### parse()

Create a new signature from a DomainKey-Signature header

```
  my $sig = Mail::DKIM::DkSignature->parse(
                  'DomainKey-Signature: a=rsa-sha1; b=yluiJ7+0=; c=nofws'
            );
```

Constructs a signature by parsing the provided DomainKey-Signature header content. You do not have to include the header name (i.e. "DomainKey-Signature:") but it is recommended, so the header name can be preserved and returned the same way in "**as\_string()**".

Note: The input to this constructor is in the same format as the output of the as\_string method.

## METHODS

### as\_string()

Convert the signature header as a string.

```
  print $signature->as_string . "\n";
```

outputs

```
  DomainKey-Signature: a=rsa-sha1; b=yluiJ7+0=; c=nofws
```

As shown in the example, the as\_string method can be used to generate the DomainKey-Signature that gets prepended to a signed message.

### algorithm()

Get or set the algorithm (a=) field

The algorithm used to generate the signature. Defaults to "rsa-sha1", an RSA-signed SHA-1 digest.

### canonicalization()

Get or set the canonicalization (c=) field.

```
  $signature->canonicalization('nofws');
  $signature->canonicalization('simple');
  $method = $signature->canonicalization;
```

Message canonicalization (default is "simple"). This informs the verifier of the type of canonicalization used to prepare the message for signing.

### domain()

Get or set the domain (d=) field.

```
  my $d = $signature->domain;          # gets the domain value
  $signature->domain('example.org');   # sets the domain value
```

The domain of the signing entity, as specified in the signature. This is the domain that will be queried for the public key.

### headerlist()

Get or set the signed header fields (h=) field.

```
  $signature->headerlist('a:b:c');
  my $headerlist = $signature->headerlist;
  my @headers = $signature->headerlist;
```

Signed header fields. A colon-separated list of header field names that identify the header fields presented to the signing algorithm.

In scalar context, the list of header field names will be returned as a single string, with the names joined together with colons. In list context, the header field names will be returned as a list.

### identity()

Get the signing identity.

```
  my $i = $signature->identity;
```

In DomainKey signatures, the signing identity is the first address found in the Sender header or the From header. This field is populated by the Verifier when processing a DomainKey signature.

### identity\_source()

Determine which header had the identity.

```
  my $source = $signature->identity_source;
```

If the message is being verified, this method will tell you which of the message headers was used to determine the signature identity. Possible values are "header.sender" and "header.from".

### protocol()

Get or set the query methods (q=) field.

A colon-separated list of query methods used to retrieve the public key (default is "dns").

### selector()

Get or set the selector (s=) field.

The selector subdivides the namespace for the "d=" (domain) tag.

### signature()

Get or set the signature data (b=) field.

The signature data. Whitespace is automatically stripped from the returned value.

## SEE ALSO

Mail::DKIM::Signature for DKIM-Signature headers

## AUTHORS

- •

  Jason Long \<jason@long.name\>

- •

  Marc Bradshaw \<marc@marcbradshaw.net\>

- •

  Bron Gondwana \<brong@fastmailteam.com\> (ARC)

## THANKS

Work on ensuring that this module passes the ARC test suite was generously sponsored by Valimail (https://www.valimail.com/)

## COPYRIGHT AND LICENSE

- •

  Copyright (C) 2013 by Messiah College

- •

  Copyright (C) 2010 by Jason Long

- •

  Copyright (C) 2017 by Standcore LLC

- •

  Copyright (C) 2020 by FastMail Pty Ltd

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.6 or, at your option, any later version of Perl 5 you may have available.