PHP

Add a Detached Signature with a Separate Private Key

Demonstrates the Chilkat Mime.AddDetachedSignaturePk method, which creates a detached signature using a signer certificate and its separately supplied private key. The first argument is the Cert and the second is the PrivateKey.

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: Sometimes the certificate and its private key live apart — a .cer alongside a PEM key file, for instance — rather than bundled in a single PFX. This method pairs them explicitly for signing, whereas AddDetachedSignature expects a Cert that already provides its key. The result is the same multipart/signed message.

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<?php

use Chilkat2\Cert;
use Chilkat2\Mime;
use Chilkat2\PrivateKey;

$mime = new Mime();
try {
    $mime->SetBodyFromPlainText('This message will be signed.');

    // Load the certificate and its private key separately.
    $cert = new Cert();
    $cert->LoadFromFile('qa_data/signer.cer');

    $privKey = new PrivateKey();
    $privKey->LoadPemFile('qa_data/signer_privkey.pem');

    // Create a detached signature when the certificate and private key are supplied separately.  The
    // 1st argument is the signer certificate and the 2nd is its private key.
    $mime->AddDetachedSignaturePk($cert, $privKey);

    $mime->SaveMime('qa_output/signed.eml');
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\n";
    exit;
}

echo "Detached signature added.\n";