(Node.js) Generate RSA Key and Sign a String

See more RSA Examples

Demonstrates how to generate a new RSA public/private key pair and use it to generate a signature for a string. The (binary) digital signature is returned as a hexidecimalized string.

Install Chilkat for Node.js and Electron using npm at

Chilkat npm packages for Node.js
Chilkat npm packages for Electron
on Windows, Linux, MacOS

var os = require('os');
if (os.platform() == 'win32') {  
  var chilkat = require('@chilkat/ck-node23-win64'); 
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node23-linux-arm');
    } else if (os.arch() == 'arm64') {
        var chilkat = require('@chilkat/ck-node23-linux-arm64');
    } else {
        var chilkat = require('@chilkat/ck-node23-linux-x64');
    }
} else if (os.platform() == 'darwin') {
  var chilkat = require('@chilkat/ck-node23-mac-universal');
}

function chilkatExample() {

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

    var rsa = new chilkat.Rsa();

    // Generate a 2048-bit RSA key.
    var success = rsa.GenerateKey(2048);

    // Return the signature in hex.
    rsa.EncodingMode = "hex";

    var strData = "This is the string to be signed.";

    // Sign the SHA256 hash of the string.
    var hexSig = rsa.SignStringENC(strData,"sha256");

    console.log(hexSig);
    console.log(rsa.LastErrorText);

    // Now verify the signature:
    success = rsa.VerifyStringENC(strData,"sha256",hexSig);
    if (success == true) {
        console.log("Signature verified!");
    }
    else {
        console.log(rsa.LastErrorText);
    }

    // Try it with an invalid signature:
    success = rsa.VerifyStringENC(strData,"sha256","not a valid sig");
    if (success == true) {
        console.log("Signature verified!");
    }
    else {
        console.log(rsa.LastErrorText);
    }

    // Try it with invalid data:
    success = rsa.VerifyStringENC("Not the original data","sha256",hexSig);
    if (success == true) {
        console.log("Signature verified!");
    }
    else {
        console.log(rsa.LastErrorText);
    }

    // Try it with the wrong hash algorithm:
    success = rsa.VerifyStringENC(strData,"sha-1",hexSig);
    if (success == true) {
        console.log("Signature verified!");
    }
    else {
        console.log(rsa.LastErrorText);
    }


}

chilkatExample();