(JavaScript) Validate JWS Using HMAC SHA-256

Validates a JSON Web Signature (JWS) using HMAC SHA-256.

Note: This example requires Chilkat v11.0.0 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.

// This example takes a JSON signature in compact serialization format,
// and uses a MAC key to validate and recover the protected header and payload.

var jws = new CkJws();

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

// Load the JWS.
var jwsCompact = "eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ.dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk";
success = jws.LoadJws(jwsCompact);

// Validate the 1st (and only) signature at index 0..
var v = jws.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(jws.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("Recovered content:");
console.log(jws.GetPayload("utf-8"));

// Examine the protected header:

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

joseHeader.EmitCompact = false;

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

// Output:

// 	Signature validated.
// 	Recovered content:
// 	{"iss":"joe",
// 	 "exp":1300819380,
// 	 "http://example.com/is_root":true}
// 	Protected (JOSE) header:
// 	{ 
// 	  "typ": "JWT",
// 	  "alg": "HS256"
// 	}