PHP ActiveX

Export an Encrypted PKCS #8 Private Key as PEM

Demonstrates the Chilkat PrivateKey.GetPkcs8EncryptedPem method, which exports the key as password-protected PKCS #8 PEM (-----BEGIN ENCRYPTED PRIVATE KEY-----). The only argument is the password; the cipher is selected by the Pkcs8EncryptAlg property.

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: This is the safe way to export a key for storage or transfer — the private material is encrypted under a passphrase, so a leaked file is not immediately usable. It is the format to reach for whenever a key leaves your process. Control the encryption cipher with Pkcs8EncryptAlg, and source the password securely rather than hard-coding it.

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<?php

$success = 0;

//  Load a private key to export.
$privKey = new COM("Chilkat.PrivateKey");
$success = $privKey->LoadPemFile('qa_data/private.pem');
if ($success == 0) {
    print $privKey->LastErrorText . "\n";
    exit;
}

//  The key password is not hard-coded in a real application; obtain it from an interactive
//  prompt, environment variable, or a secrets vault.
$password = 'myKeyPassword';

//  Export as password-protected PKCS #8 PEM ("-----BEGIN ENCRYPTED PRIVATE KEY-----").  The
//  encryption cipher is selected by the Pkcs8EncryptAlg property.
$pem = $privKey->getPkcs8EncryptedPem($password);
if ($privKey->LastMethodSuccess == 0) {
    print $privKey->LastErrorText . "\n";
    exit;
}

print $pem . "\n";

?>