(Node.js) Export Digital Certificate's Public Key

The ExportPublicKey method can be called to get a certificate's public key. It can then be saved to any of a number of formats: (1) OpenSSL DER, (2) OpenSSL PEM, (3) RSA DER, (4) XML.

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 cert = new chilkat.Cert();

    // LoadFromFile will load virtually any certificate format file.
    // It will auto-recognize the format and load appropiately.
    var success = cert.LoadFromFile("/Users/chilkat/testData/cer/chilkat.cer");
    if (success !== true) {
        console.log(cert.LastErrorText);
        return;
    }

    // Get the public key:
    // pubkey: PublicKey
    var pubkey;

    pubkey = cert.ExportPublicKey();
    if (cert.LastMethodSuccess == false) {
        console.log(cert.LastErrorText);
        return;
    }

    // Save to various formats:
    success = pubkey.SaveDerFile(false,"/Users/chilkat/testData/pubkeys/chilkat_pkcs8.der");
    if (success !== true) {
        console.log(pubkey.LastErrorText);

        return;
    }

    success = pubkey.SavePemFile(false,"/Users/chilkat/testData/pubkeys/chilkat.pem");
    if (success !== true) {
        console.log(pubkey.LastErrorText);

        return;
    }

    success = pubkey.SaveDerFile(true,"/Users/chilkat/testData/pubkeys/chilkat_pkcs1.der");
    if (success !== true) {
        console.log(pubkey.LastErrorText);

        return;
    }

    success = pubkey.SaveXmlFile("/Users/chilkat/testData/pubkeys/chilkat.xml");
    if (success !== true) {
        console.log(pubkey.LastErrorText);

        return;
    }

    console.log("Public key exported to all file formats.");

}

chilkatExample();