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 Module Downloads for Windows, Linux, and MAC OS X

use chilkat();

#  Important: It is helpful to send the contents of the
#  dkim.LastErrorText property when requesting support.

$dkim = new chilkat::CkDkim();

#  Any string automatically begins a fully-functional 30-day trial.
$success = $dkim->UnlockComponent("Anything for 30-day trial");
if ($success != 1) {
    print $dkim->lastErrorText() . "\n";
    exit;
}

#  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";
$success = $dkim->LoadDkimPkFile("myPrivateKey.pem",$password);
if ($success != 1) {
    print $dkim->lastErrorText() . "\n";
    exit;
}

#  Load a MIME file.
$mimeData = new chilkat::CkByteData();

$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 = new chilkat::CkByteData();
$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." . "\n";