(JavaScript) JWE using AES Key Wrap and AES_128_CBC_HMAC_SHA_256

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.

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: {"alg":"A128KW","enc":"A128CBC-HS256"}
var jweProtHdr = new CkJsonObject();
jweProtHdr.AppendString("alg","A128KW");
jweProtHdr.AppendString("enc","A128CBC-HS256");
jwe.SetProtectedHeader(jweProtHdr);

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

// 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:
var aesWrappingKey = "GawgguFyGrWKav7AX4VKUg";
jwe.SetWrappingKey(0,aesWrappingKey,"base64url");

// 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 that was just produced.
// 1) Load the JWE.
// 2) Set the AES wrapping key.
// 3) Decrypt.
var jwe2 = new CkJwe();
success = jwe2.LoadJwe(strJwe);
if (success !== true) {
    console.log(jwe2.LastErrorText);
    return;
}

// Set the AES wrap key.
jwe2.SetWrappingKey(0,aesWrappingKey,"base64url");

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

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

// ---------------------------------------------------------------------------------
// 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.

var sbJwe = new CkStringBuilder();
sbJwe.Append("eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.");
sbJwe.Append("6KB707dM9YTIgHtLvtgWQ8mKwboJW3of9locizkDTHzBC2IlrT1oOQ.");
sbJwe.Append("AxY8DCtDaGlsbGljb3RoZQ.");
sbJwe.Append("KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY.");
sbJwe.Append("U0m_YmjN04DJvceFICbCVQ");

success = jwe2.LoadJweSb(sbJwe);
if (success !== true) {
    console.log(jwe2.LastErrorText);
    return;
}

jwe2.SetWrappingKey(0,aesWrappingKey,"base64url");

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

console.log(originalPlaintext);