(JavaScript) Verfies an RSA Signature

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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;

// The following data was signed by the following example:
// RSA Sign using a Private Key on a USB Token or Smartcard
var bd = new CkBinData();
var i;
for (i = 0; i <= 100; i++) {
    bd.AppendEncoded("000102030405060708090A0B0C0D0E0F","hex");
}

// Load the signature
var bdSig = new CkBinData();
success = bdSig.LoadFile("rsaSignatures/test1.sig");
if (success == false) {
    console.log("Failed to load the RSA signature");
    return;
}

// Get the public key to be used for signature verification.
var pubKey = new CkPublicKey();
success = pubKey.LoadFromFile("rsaKeys/chilkat-rsa-2048.pem");
if (success == false) {
    console.log(pubKey.LastErrorText);
    return;
}

var rsa = new CkRsa();
success = rsa.UsePublicKey(pubKey);
if (success == false) {
    console.log(rsa.LastErrorText);
    return;
}

// Verify the hash of the data against the signature.
// We pass in the original data.  Internally, the hash is generated
// and used to validate the signature.
// Validating the RSA signature means two things:  
// (1) the original data is exactly what was signed, and 
// (2) it was signed by the owner of the RSA private key.
success = rsa.VerifyBd(bd,"sha256",bdSig);

if (success == false) {
    console.log(rsa.LastErrorText);
    console.log("Signature invalid.");
}
else {
    console.log("Signature valid.");
}