(Node.js) Verify the RSA Signature of a SHA256 Hash

See more RSA Examples

Demonstrates how to verify an RSA signature of a SHA256 hash.

Install Chilkat for Node.js and Electron using npm at Chilkat npm packages for Node.js Chilkat npm packages for Electron on Windows, Linux, MacOSX, and ARM

var os = require('os');
if (os.platform() == 'win32') {  
    if (os.arch() == 'ia32') {
        var chilkat = require('@chilkat/ck-node21-win-ia32');
    } else {
        var chilkat = require('@chilkat/ck-node21-win64'); 
    }
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node21-arm');
    } else if (os.arch() == 'x86') {
        var chilkat = require('@chilkat/ck-node21-linux32');
    } else {
        var chilkat = require('@chilkat/ck-node21-linux64');
    }
} else if (os.platform() == 'darwin') {
    if (os.arch() == 'arm64') {
        var chilkat = require('@chilkat/ck-node21-mac-m1');
    } else {
        var chilkat = require('@chilkat/ck-node21-macosx');
    }
}

function chilkatExample() {

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

    var rsa = new chilkat.Rsa();

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

    // Get the 32-byte SHA256 hash.
    var bdHash = new chilkat.BinData();
    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 chilkat.BinData();
    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.");

}

chilkatExample();