(JavaScript) ECDSA Sign and Verify Data using Different Hash Algorithms

Demonstrates how to create ECDSA signatures on data using different hash algorithms.

Note: This example requires Chilkat v9.5.0.85 or greater because the SignBd and VerifyBd methods were added in v9.5.0.85.

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

// First load an ECDSA private key to be used for signing.
var privKey = new CkPrivateKey();
success = privKey.LoadEncryptedPemFile("qa_data/ecc/secp256r1-key-pkcs8-secret.pem","secret");
if (success == false) {
    console.log(privKey.LastErrorText);
    return;
}

// Load some data to be signed.
var bd = new CkBinData();
success = bd.LoadFile("qa_data/hamlet.xml");
if (success == false) {
    console.log("Failed to load file to be hashed.");
    return;
}

var ecdsa = new CkEcc();
var prng = new CkPrng();

// Sign the sha256 hash of the data.  Return the ECDSA signature in the base64 encoding.
console.log("ECDSA signing the sha256 hash of the data...");
var sig = ecdsa.SignBd(bd,"sha256","base64",privKey,prng);
console.log("sig = " + sig);

// Verify the signature against the original data.
// (We must use the same hash algorithm that was used when signing.)

// Load the public key that corresponds to the private key used for signing.
var pubKey = new CkPublicKey();
success = pubKey.LoadFromFile("qa_data/ecc/secp256r1-pub.pem");
if (success == false) {
    console.log(pubKey.LastErrorText);
    return;
}

var ecc2 = new CkEcc();
var result = ecc2.VerifyBd(bd,"sha256",sig,"base64",pubKey);
if (result !== 1) {
    console.log(ecc2.LastErrorText);
    return;
}

console.log("Verified!");

// ----------------------------------------------------------------------------------------
// Let's do the same thing, but with sha384 hashing...

console.log("--------------------------------------------");
console.log("ECDSA signing the sha384 hash of the data...");

sig = ecdsa.SignBd(bd,"sha384","base64",privKey,prng);
console.log("sig = " + sig);

result = ecc2.VerifyBd(bd,"sha384",sig,"base64",pubKey);
if (result !== 1) {
    console.log(ecc2.LastErrorText);
    return;
}

console.log("Verified!");