(Perl) Add DKIM-Signature Header to MIME / Email

Demonstrates how to add a DKIM-Signature header field to a MIME message.

Note: The DKIM / DomainKey functionality is included with the Chilkat MIME license.

Chilkat Perl Downloads Perl Module for Windows, MacOS, Linux, Alpine Linux, Solaris

use chilkat();

# This example requires the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

$dkim = chilkat::CkDkim->new();

# To create a DKIM signature for email (i.e. MIME),
# you'll need to provide the following:
# (1) An RSA private key in any common file format.
# (2) The domain name (typically the same domain
# as the sender of an email).
# (3) A selector for the domain name -- an arbitrary string
# to identify the matching public key in DNS.

# To allow an email recipient to verify the DKIM signature via an
# external email client supporting DKIM or using other software,
# you will need to create a DNS record with the selector
# and matching public key.  This example does not provide
# information about DKIM DNS record creation.  
# (Chilkat does not provide an API for creating DNS records.  
# Creating the DKIM DNS record is something you would do
# manually.)

# Set the domain and selector:
# You'll need to provide your own values here..
$dkim->put_DkimDomain("chilkatsoft.com");
$dkim->put_DkimSelector("tuna");

# Load a private key from any common RSA private key
# format, such as DER, PKCS8, PEM, XML, etc.
# The LoadDkimPkFile method automatically detects
# the file format and reads it appropriately.
# If a password is not required, you'll still need to provide
# a password string argument, but it is ignored.

$password = "optionalPassword";
$privKey = chilkat::CkPrivateKey->new();
$success = $privKey->LoadAnyFormatFile("myPrivateKey.pem",$password);
if ($success != 1) {
    print $privKey->lastErrorText() . "\r\n";
    exit;
}

$success = $dkim->SetDkimPrivateKey($privKey);
if ($success != 1) {
    print $dkim->lastErrorText() . "\r\n";
    exit;
}

# Load a MIME file.
$mimeData = chilkat::CkByteData->new();
$success = $mimeData->loadFile("testMessage.eml");
if ($success != 1) {
    print "Failed to load file." . "\r\n";
    exit;
}

# Sign it.  This adds the DKIM-Signature header and
# returns the new MIME with DKIM-Signature added.
$dkimSignedMime = chilkat::CkByteData->new();
$success = $dkim->AddDkimSignature($mimeData,$dkimSignedMime);
if ($success != 1) {
    print $dkim->lastErrorText() . "\r\n";
    exit;
}

$success = $dkimSignedMime->saveFile("dkimSigned.eml");
if ($success != 1) {
    print "Failed to save file." . "\r\n";
    exit;
}

print "Success." . "\r\n";