PHP

JWE using AES Key Wrap and AES_128_CBC_HMAC_SHA_256

See more JSON Web Encryption (JWE) Examples

This example duplicates the example A.3 in RFC 7516 for JSON Web Encryption (JWE).

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

Chilkat2 PHP

<?php

use Chilkat2\JsonObject;
use Chilkat2\Jwe;
use Chilkat2\StringBuilder;

// 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: {"alg":"A128KW","enc":"A128CBC-HS256"}
$jweProtHdr = new JsonObject();
$jweProtHdr->AppendString('alg', 'A128KW');
$jweProtHdr->AppendString('enc', 'A128CBC-HS256');
$jwe->SetProtectedHeader($jweProtHdr);

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

// The example A.3 in RFC 7516 uses the following 128-bit AES key,
// specified in JWK (JSON Web Key) format:
//      {"kty":"oct",
//       "k":"GawgguFyGrWKav7AX4VKUg"
//      }
// This is just a way of saying: The key type ("kty") is
// a bunch of octets ("k") in base64url encoding.
// We can simply set the AES wrapping key like this:
$aesWrappingKey = 'GawgguFyGrWKav7AX4VKUg';
$jwe->SetWrappingKey(0, $aesWrappingKey, 'base64url');

// 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 that was just produced.
// 1) Load the JWE.
// 2) Set the AES wrapping key.
// 3) Decrypt.
$jwe2 = new Jwe();
try {
    $jwe2->LoadJwe($strJwe);

    // Set the AES wrap key.
    $jwe2->SetWrappingKey(0, $aesWrappingKey, 'base64url');

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

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

// ---------------------------------------------------------------------------------
// It should also be possible to decrypt the JWE as shown in RFC 7516, Appendix A.3.7
// because it was produced using the same AES Wrap key.

$sbJwe = new StringBuilder();
$sbJwe->Append('eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.');
$sbJwe->Append('6KB707dM9YTIgHtLvtgWQ8mKwboJW3of9locizkDTHzBC2IlrT1oOQ.');
$sbJwe->Append('AxY8DCtDaGlsbGljb3RoZQ.');
$sbJwe->Append('KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY.');
$sbJwe->Append('U0m_YmjN04DJvceFICbCVQ');

try {
    $jwe2->LoadJweSb($sbJwe);

    $jwe2->SetWrappingKey(0, $aesWrappingKey, 'base64url');

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

echo $originalPlaintext, "\n";