(JavaScript) JWE with DEFLATE Compression

Demonstrates how to DEFLATE ("zip") compress the JWE payload prior to encryption.

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.

// Create some plaintext to be encrypted.
// This example will demonstrate with and without DEFLATE (zip) compression.
var sbPlainText = new CkStringBuilder();
var bCrLf = true;
var line = "Live long and prosper.";
sbPlainText.AppendLine(line,bCrLf);
sbPlainText.AppendLine(line,bCrLf);
sbPlainText.AppendLine(line,bCrLf);
sbPlainText.AppendLine(line,bCrLf);

// The text to be encrypted:
console.log(sbPlainText.GetAsString());

var jwe = new CkJwe();

// Build the JWE Protected Header: {"alg":"A128KW","enc":"A128CBC-HS256","zip":"DEF"}
// The "zip":"DEF" parameter indicates that the plaintext payload should
// be compressed prior to encryption.
var jweProtHdr = new CkJsonObject();
jweProtHdr.AppendString("alg","A128KW");
jweProtHdr.AppendString("enc","A128CBC-HS256");
jweProtHdr.AppendString("zip","DEF");
jwe.SetProtectedHeader(jweProtHdr);

// Set the AES key wrap key:
var aesWrappingKey = "GawgguFyGrWKav7AX4VKUg";
jwe.SetWrappingKey(0,aesWrappingKey,"base64url");

// Encrypt and return the JWE in sbJweCompressed:
var sbJweCompressed = new CkStringBuilder();
success = jwe.EncryptSb(sbPlainText,"utf-8",sbJweCompressed);
if (success !== true) {
    console.log(jwe.LastErrorText);
    return;
}

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

// Now create a JWE without compression.
jweProtHdr.Delete("zip");
// Make sure to update the shared protected header:
jwe.SetProtectedHeader(jweProtHdr);

var sbJweUncompressed = new CkStringBuilder();
success = jwe.EncryptSb(sbPlainText,"utf-8",sbJweUncompressed);
if (success !== true) {
    console.log(jwe.LastErrorText);
    return;
}

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

// Decrypting is the same whether compression is used or not.
// The "zip" header in the JWE indicates that the payload should be 
// automatically decompressed (inflated) after decrypting.
var jwe2 = new CkJwe();
success = jwe2.LoadJweSb(sbJweCompressed);
if (success !== true) {
    console.log(jwe2.LastErrorText);
    return;
}

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

// Decrypt (also automatically decompresses).
var sbOriginalText = new CkStringBuilder();
success = jwe2.DecryptSb(0,"utf-8",sbOriginalText);
if (success !== true) {
    console.log(jwe2.LastErrorText);
    return;
}

console.log("original text from compressed JWE: ");
console.log(sbOriginalText.GetAsString());

// -----------------------------------------------------------
// Do the same with the uncompressed JWE

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

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

// Decrypt.
sbOriginalText.Clear();
success = jwe2.DecryptSb(0,"utf-8",sbOriginalText);
if (success !== true) {
    console.log(jwe2.LastErrorText);
    return;
}

console.log("original text from uncompressed JWE: ");
console.log(sbOriginalText.GetAsString());

// ------------------------------------------------
// The output of this example is:
// (Note: Your output data will be different because the content encryption key is randomly generated.)

// eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2IiwiemlwIjoiREVGIn0.xuW-pEAIdEUFnk10m8ocursvktO8Of9ByCCAt6LgKkkOtCWCUn1kQw.zpGj-9WVni3cQxyOuZbcGA.0hzP1myua3oYpUHwCIY_3edBUREbUpLaX6wYuJduOdI.Ppc6aEO3y3B8BJ1FKMPjlA
// size of compressed JWE: 212
// eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.N4KeyC7nnSFkieJOyE24_zKeuV_m7v5UKoJb1TgV4Yc_r2RzUPNvyA.6AEdyXSCKx-iMmUJyypSLg.QpixfyrwhGpmwUDp623viik4smPav7vwPLiC2r-V-jwnSfEH3mxWu6DbrIz3mixaqATwynmEBzVPxvS9jTXpSAGCnniib4_0WoPl3r_wF5tlsKOEe--jpNso-DKd1Tp8jJxj3JkFWt3IRnUUKGj17g.sBfDwFc5fzpaI-UW8-SW4g
// size of uncompressed JWE: 303
// original text from compressed JWE: 
// Live long and prosper.
// Live long and prosper.
// Live long and prosper.
// Live long and prosper.
// 
// original text from uncompressed JWE: 
// Live long and prosper.
// Live long and prosper.
// Live long and prosper.
// Live long and prosper.
//