PHP

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

use Chilkat2\PrivateKey;

// Load a private key to export.
$privKey = new PrivateKey();
try {
    $privKey->LoadPemFile('qa_data/private.pem');

    // 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);
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\n";
    exit;
}

echo $pem, "\n";