PHP

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

use Chilkat2\Dkim;
use Chilkat2\PrivateKey;

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

$dkim = new Dkim();

// Load the RSA private key that corresponds to the public key published in the domain's DNS.
$privKey = new PrivateKey();
try {
    $privKey->LoadPemFile('qa_data/dkim_private.pem');

    // Copy the key into the Dkim object.  The PrivateKey object may be destroyed afterward, and the
    // configured key can be reused for multiple signatures.
    $dkim->SetDkimPrivateKey($privKey);
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\n";
    exit;
}

echo "DKIM private key configured.\n";