PHP

JWE using PBES2 Key Wrapping

See more JSON Web Encryption (JWE) Examples

Demonstrates how to create and decrypt a JWE that using PBES2 key wrapping.

This example demonstrates PBES2 with HMAC SHA-256 and A128KW wrapping. It is also possible to do the following by simply changing the "alg" parameter:

• PBES2 with HMAC SHA-384 and A192KW wrapping
• PBES2 with HMAC SHA-512 and A256KW wrapping

Note: This example requires Chilkat v9.5.0.66 or greater.

Chilkat2 PHP

<?php

use Chilkat2\JsonObject;
use Chilkat2\Jwe;
use Chilkat2\Prng;

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

// Note: This example requires Chilkat v9.5.0.66 or greater.

$plaintext = 'Live long and prosper.';

$jwe = new Jwe();

// First build the JWE Protected Header..
$jweProtHdr = new JsonObject();
$jweProtHdr->AppendString('alg', 'PBES2-HS256+A128KW');
$jweProtHdr->AppendString('enc', 'A128GCM');

// PBES2 requires two additional parameters:
// 1) A random salt parameter ("p2s") containing 8 or more bytes in base64url format.
// 2) An iteration count parameter ("p2c").  A minimum count of 1000 is recommended.
//    The iteration count is intended to make the PBES2 computation more expensive (time consuming)
//    to prevent brute-force attacks.
$prng = new Prng();
$jweProtHdr->AppendString('p2s', $prng->GenRandom(16, 'base64url'));
$jweProtHdr->AppendString('p2c', '1000');

echo 'JWE Protected Header: ', $jweProtHdr->Emit(), "\n";
echo "--\n";

// Don't forget to actually provide the protected header to the JWE object:
$jwe->SetProtectedHeader($jweProtHdr);

// Set the PBES2 password
$recipientIndex = 0;
$jwe->SetPassword($recipientIndex, 'top secret');

// Encrypt and return the JWE:
try {
    $strJwe = $jwe->Encrypt($plaintext, 'utf-8');
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\n";
    exit;
}

// Show the JWE we just created:
echo $strJwe, "\n";

// Decrypt the JWE.
$jwe2 = new Jwe();
try {
    $jwe2->LoadJwe($strJwe);

    // Set the PBES2 password
    $jwe2->SetPassword($recipientIndex, 'top secret');

    // Decrypt.
    $originalPlaintext = $jwe2->Decrypt(0, 'utf-8');
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\n";
    exit;
}

echo "original text: \n";
echo $originalPlaintext, "\n";

// Sample output:

// JWE Protected Header: {"alg":"PBES2-HS256+A128KW","enc":"A128GCM","p2s":"z39rTEfRy1T1Yn_D1mZRlg","p2c":"1000"}
// --
// eyJhbGciOiJQQkVTMi1IUzI1NitBMTI4S1ciLCJlbmMiOiJBMTI4R0NNIiwicDJzIjoiejM5clRFZlJ5MVQxWW5fRDFtWlJsZyIsInAyYyI6IjEwMDAifQ.koYt6PrFmYwcwdcT7ZcvXHA1d-Xez5h4.luGlbvEnZp-7IsBOj42Yhw.YMTcfLf8Qe4zazozGV2OAu3cUdQ8Kg.rWub47ESWkc6IqZJTvSTmg
// original text:
// Live long and prosper.