(JavaScript) Verify the RSA Signature of a SHA256 Hash

See more RSA Examples

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

// Let's say you have a file containing the 32-bytes of a SHA256 hash,
// and a file that is an RSA signature of those 32 bytes.
// Here's how you verify using the RSA public key found in a PEM.

var pubKey = new CkPublicKey();
success = pubKey.LoadFromFile("rsaPubKey.pem");
if (success == false) {
    console.log(pubKey.LastErrorText);
    return;
}

var rsa = new CkRsa();

// Get the public key.
success = rsa.UsePublicKey(pubKey);
if (success == false) {
    console.log(rsa.LastErrorText);
    return;
}

// Get the 32-byte SHA256 hash.
var bdHash = new CkBinData();
success = bdHash.LoadFile("myHash.sha256");
if (success == false) {
    console.log("Failed to load SHA256 hash.");
    return;
}

// Get the RSA signature to be validated.
var bdSig = new CkBinData();
success = bdSig.LoadFile("mySig.sig");
if (success == false) {
    console.log("Failed to load RSA signature.");
    return;
}

// Verify the signature against the SHA256 hash.
var enc = "base64";
rsa.EncodingMode = enc;
success = rsa.VerifyHashENC(bdHash.GetEncoded(enc),"sha256",bdSig.GetEncoded(enc));
if (success == false) {
    console.log(rsa.LastErrorText);
    return;
}

console.log("Signature validated.");