(PHP Extension) RSA Encrypt Randomly Generated AES Key

Demonstrates how to RSA encrypt a randomly generated AES key.

Chilkat PHP Downloads PHP Extension for Windows, Linux, MacOS, Alpine Linux, Solaris

<?php

// The version number (9_5_0) should match version of the Chilkat extension used, omitting the micro-version number.
// For example, if using Chilkat v9.5.0.48, then include as shown here:
include("chilkat_9_5_0.php");

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// First generate a 256-bit AES key (32 bytes).
$prng = new CkPrng();
$bdAesKey = new CkBinData();
$success = $prng->GenRandomBd(32,$bdAesKey);

// Use a public key from a certificate for RSA encryption.
$cert = new CkCert();

$success = $cert->LoadFromFile('qa_data/pem/mf_public_rsa.pem');
if ($success == false) {
    print $cert->lastErrorText() . "\n";
    exit;
}

// pubKey is a CkPublicKey
$pubKey = $cert->ExportPublicKey();
if ($cert->get_LastMethodSuccess() != true) {
    print $cert->lastErrorText() . "\n";
    exit;
}

$rsa = new CkRsa();
$success = $rsa->ImportPublicKeyObj($pubKey);
if ($success == false) {
    print $rsa->lastErrorText() . "\n";
    exit;
}

// RSA encrypt our 32-byte AES key.
// The contents of bdAesKey are replaced with result of the RSA encryption.
$success = $rsa->EncryptBd($bdAesKey,false);
if ($success == false) {
    print $rsa->lastErrorText() . "\n";
    exit;
}

// Return the result as a base64 string
$encryptedAesKey = $bdAesKey->getEncoded('base64');

print 'encrypted AES key = ' . $encryptedAesKey . "\n";

?>