(Node.js) Get a Certificate's Key Size

Demonstrates how to get the RSA key size of a certificate (for example, 1024-bit, 2048-bit, etc.)

Note: This example requires Chilkat v11.0.0 or greater.

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() {

    var success = false;

    // For this example, I have a certificate in raw base64 format (not PEM),
    // that looks like this:  "MIIGkDCCBHigAwIBAgIUMDA ... s/iqLsLA=="
    var sbCertBase64 = new chilkat.StringBuilder();
    success = sbCertBase64.LoadFile("qa_data/certs/base64Cert.txt","utf-8");

    var cert = new chilkat.Cert();
    success = cert.LoadFromBase64(sbCertBase64.GetAsString());
    if (success == false) {
        console.log(cert.LastErrorText);
        return;
    }

    // Get the public key.
    var pubKey = new chilkat.PublicKey();
    cert.GetPublicKey(pubKey);

    var numBits = pubKey.KeySize;
    console.log("Number of bits = " + numBits);

    // If using an older version of Chilkat, the key size can be obtained like this:
    var xml = new chilkat.Xml();
    xml.LoadXml(pubKey.GetXml());

    var binDat = new chilkat.BinData();
    binDat.AppendEncoded(xml.GetChildContent("Modulus"),"base64");

    numBits = 8 * binDat.NumBytes;
    console.log("Number of bits = " + numBits);

}

chilkatExample();