(Node.js) How to Parse a X.509 Certificate and Extract its Public Key

Demonstrates how to load an X.509 certificate and extract the public key. Chilkat supports many certificate encodings:

• DER (binary) encoded certificates (.crt/.cer)
• PEM (BASE64) encoded certificates (.pem)
• Load Certificates Directly from Windows Certificate Stores
• PFX/PKCS12 (.pfx/.p12)
• Java KeyStore (.jks)
• Cryptographic Message Syntax Standard - PKCS #7 Certificates (.P7B)

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() {

    var cert = new chilkat.Cert();

    // Load a DER (binary) encoded certificate.
    // To load from a .pem or .p7b, or any other file format that contains
    // just one certificate, call LoadFromFile in exactly the same way.
    // The LoadFromFile method automatically detects the format and loads the certificate.
    var success = cert.LoadFromFile("qa_data/certs/testCert.cer");
    if (success == false) {
        console.log(cert.LastErrorText);
        return;
    }

    // Get the public key:
    // pubKey: PublicKey
    var pubKey = cert.ExportPublicKey();
    if (cert.LastMethodSuccess !== true) {
        console.log(cert.LastErrorText);
        return;
    }

    // Examine the key type.
    // A PublicKey object can contain an RSA, ECC, or DSA public key.
    // The KeyType property will contain "rsa", "ecc", or "dsa".
    console.log("key type = " + pubKey.KeyType);


}

chilkatExample();