(JavaScript) JWE with Binary Data

Demonstrates how to create a JWE that contains a binary payload (such as a JPG image).

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.

// Load a JPG file that will be the JWE payload.
var jpgBytes = new CkBinData();
success = jpgBytes.LoadFile("qa_data/jpg/starfish.jpg");
// Make sure your app checks the success/failure of the call to LoadFile..
console.log("Original JPG size = " + jpgBytes.NumBytes);

var jwe = new CkJwe();

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

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

// Encrypt and return the JWE in sbJwe:
var sbJwe = new CkStringBuilder();
success = jwe.EncryptBd(jpgBytes,sbJwe);
if (success !== true) {
    console.log(jwe.LastErrorText);
    return;
}

// Show the JWE:
console.log(sbJwe.GetAsString());
console.log("size of JWE: " + sbJwe.Length);

// ---------------------------------------------------------
// Decrypt to get the original JPG file..

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

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

// Decrypt.
var jpgOriginal = new CkBinData();
success = jwe2.DecryptBd(0,jpgOriginal);
if (success !== true) {
    console.log(jwe2.LastErrorText);
    return;
}

console.log("Decrypted JPG size = " + jpgOriginal.NumBytes);

// Save the decrypted JPG to a file.
success = jpgOriginal.WriteFile("qa_output/jwe_decrypted_starfish.jpg");

console.log("success = " + success);

// The output of this program, when tested, was:
// Original JPG size = 6229
// eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.9YFz_wteV ... 7Et3hKhpxnKEXw
// size of JWE: 8473
// Decrypted JPG size = 6229
// success = True