JWS Using HMAC SHA-256

See more JSON Web Signatures (JWS) Examples

var success = false;

// This requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// First create the JWS Protected Header
var jwsProtHdr = new CkJsonObject();
jwsProtHdr.AppendString("typ","JWT");
jwsProtHdr.AppendString("alg","HS256");
console.log("JWS Protected Header: " + jwsProtHdr.Emit());

// Output:
// JWS Protected Header: {"typ":"JWT","alg":"HS256"}

var jws = new CkJws();

// Set the HMAC key:
var hmacKey = "AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow";
var signatureIndex = 0;
jws.SetMacKey(signatureIndex,hmacKey,"base64url");

// Set the protected header:
jws.SetProtectedHeader(signatureIndex,jwsProtHdr);

// Set the payload.
var bIncludeBom = false;
var payloadStr = "In our village, folks say God crumbles up the old moon into stars.";
jws.SetPayload(payloadStr,"utf-8",bIncludeBom);

// Create the JWS
// By default, the compact serialization is used.
var jwsCompact = jws.CreateJws();
if (jws.LastMethodSuccess == false) {
    console.log(jws.LastErrorText);
    return;
}

console.log("JWS: " + jwsCompact);

// sample output:
// JWS: eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu.bsYsi8HJ0N6OqGI1hKQ9QQRNPxxA5qMpcHLtOvXatk8

// Now load the JWS, validate, and recover the original text.
var jws2 = new CkJws();

// Load the JWS.
success = jws2.LoadJws(jwsCompact);

// Set the MAC key used for validation.
signatureIndex = 0;
jws2.SetMacKey(signatureIndex,hmacKey,"base64url");

// Validate the 1st (and only) signature at index 0..
var v = jws2.Validate(signatureIndex);
if (v < 0) {
    // Perhaps Chilkat was not unlocked or the trial expired..
    console.log("Method call failed for some other reason.");
    console.log(jws2.LastErrorText);
    return;
}

if (v == 0) {
    console.log("Invalid signature.  The MAC key was incorrect, the JWS was invalid, or both.");
    return;
}

// If we get here, the signature was validated..
console.log("Signature validated.");

// Recover the original content:
console.log(jws2.GetPayload("utf-8"));

// Examine the protected header:

var joseHeader = new CkJsonObject();
success = jws2.GetProtectedH(signatureIndex,joseHeader);
if (success == false) {
    console.log(jws2.LastErrorText);
    return;
}

joseHeader.EmitCompact = false;

console.log("Protected (JOSE) header:");
console.log(joseHeader.Emit());

// Output:

// 	Signature validated.
// 	In our village, folks say God crumbles up the old moon into stars.
// 	Protected (JOSE) header:
// 	{ 
// 	  "typ": "JWT",
// 	  "alg": "HS256"
// 	}