(JavaScript) JWE using PBES2 Key Wrapping

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.

Note

This example is intended for running within a Chilkat.Js embedded JavaScript engine. All Chilkat JavaScript examples require Chilkat v11.4.0 or greater.

var success = false;

// 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.

var plaintext = "Live long and prosper.";

var jwe = new CkJwe();

// First build the JWE Protected Header..
var jweProtHdr = new CkJsonObject();
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.
var prng = new CkPrng();
jweProtHdr.AppendString("p2s",prng.GenRandom(16,"base64url"));
jweProtHdr.AppendString("p2c","1000");

console.log("JWE Protected Header: " + jweProtHdr.Emit());
console.log("--");

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

// Set the PBES2 password
var recipientIndex = 0;
jwe.SetPassword(recipientIndex,"top secret");

// Encrypt and return the JWE:
var strJwe = jwe.Encrypt(plaintext,"utf-8");
if (jwe.LastMethodSuccess !== true) {
    console.log(jwe.LastErrorText);
    return;
}

// Show the JWE we just created:
console.log(strJwe);

// Decrypt the JWE.
var jwe2 = new CkJwe();
success = jwe2.LoadJwe(strJwe);
if (success !== true) {
    console.log(jwe2.LastErrorText);
    return;
}

// Set the PBES2 password
jwe2.SetPassword(recipientIndex,"top secret");

// Decrypt.
var originalPlaintext = jwe2.Decrypt(0,"utf-8");
if (jwe2.LastMethodSuccess !== true) {
    console.log(jwe2.LastErrorText);
    return;
}

console.log("original text: ");
console.log(originalPlaintext);

// 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.