PHP Extension

Set the DKIM Signing Private Key

Demonstrates the Chilkat Dkim.SetDkimPrivateKey method, which supplies the RSA private key used by DkimSign. The only argument is a PrivateKey object. The source key may be destroyed after this returns, and the configured key can be reused for multiple signatures.

Note: The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: DKIM proves a message really came from its domain by signing it with a private key that only the domain owner holds; recipients verify with the matching public key published in the domain's DNS. This method loads that private half into the Dkim object once, so a mail server can sign every outgoing message without re-reading the key each time. Because the key is the domain's signing secret, it should be protected like any other private key and never committed to source.

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PHP Extension

<?php

include("chilkat.php");

$success = false;

//  Demonstrates the Dkim.SetDkimPrivateKey method, which supplies the RSA private key used by
//  DkimSign.  The only argument is a PrivateKey object.

$dkim = new CkDkim();

//  Load the RSA private key that corresponds to the public key published in the domain's DNS.
$privKey = new CkPrivateKey();
$success = $privKey->LoadPemFile('qa_data/dkim_private.pem');
if ($success == false) {
    print $privKey->lastErrorText() . "\n";
    exit;
}

//  Copy the key into the Dkim object.  The PrivateKey object may be destroyed afterward, and the
//  configured key can be reused for multiple signatures.
$success = $dkim->SetDkimPrivateKey($privKey);
if ($success == false) {
    print $dkim->lastErrorText() . "\n";
    exit;
}

print 'DKIM private key configured.' . "\n";

?>