(Node.js) A3/A4 Certificate to Create and Verify an Opaque PKCS7/CMS Signature

Demonstrates how to use an A3 or A4 certificate w/ private key on a smartcard or token to create a PKCS7 opaque signature, and also how to verify an opaque signature.

An opaque signature is different than a detached PKCS7 signature in that it contains the original data. Verifying an opaque signature retrieves the original content.

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 crypt = new chilkat.Crypt2();

    // A certificate and private key is needed to create a signature.
    // Chilkat provides many different ways to load a certificate and private key, such
    // as from a smartcards and hardware tokens, PFX/.p12, Java keystore, JWK, Windows registry-based certificate stores, and other sources.
    // This example will load the default certificate from the smartcard that is currently in
    // the smartcard reader.

    var cert = new chilkat.Cert();

    // If the smartcard or token requires a PIN, we can set it here to avoid the dialog...
    cert.SmartCardPin = "000000";

    var success = cert.LoadFromSmartcard("");
    if (success !== true) {
        console.log(cert.LastErrorText);
        return;
    }

    // Tell it to use the cert and private key we've loaded.
    success = crypt.SetSigningCert(cert);
    if (success !== true) {
        console.log(crypt.LastErrorText);
        return;
    }

    // Indicate we want the opaque signature in base64 format:
    crypt.EncodingMode = "base64";

    // Sign the string using the "utf-8" byte representation:
    crypt.Charset = "utf-8";

    // Create the opaque signature:
    var originalData = "This is the string to be signed.";
    var opaqueSig = crypt.OpaqueSignStringENC(originalData);
    if (crypt.LastMethodSuccess !== true) {
        console.log(crypt.LastErrorText);
        return;
    }

    console.log(opaqueSig);

    // The output looks like this:
    // MIIPgQYJKoZIhvcNAQcCoIIPcjCCD24CAQExCzAJBgUrDgMCGgUAMC8GCSqGSIb3DQEHAaAiBCBUaGlzIGlzIHRoZSBzdHJpbmcgdG8gYmUgc...

    // ----------------------------------------------------------------------------------------------
    // Now let's verify the signature and retrieve the original data.
    // We'll use a new Crypt2 object to keep things completely separate...

    var vCrypt = new chilkat.Crypt2();

    // We only need the certificate to verify a signature (and extract the data from
    // an opaque signature).  The public key is always embedded within a certificate.
    success = vCrypt.SetVerifyCert(cert);
    if (success !== true) {
        console.log(vCrypt.LastErrorText);
        return;
    }

    vCrypt.EncodingMode = "base64";
    vCrypt.Charset = "utf-8";

    var extractedData = vCrypt.OpaqueVerifyStringENC(opaqueSig);
    if (vCrypt.LastMethodSuccess !== true) {
        console.log(vCrypt.LastErrorText);
        return;
    }

    console.log("The extracted data: " + extractedData);

    // The output is:
    // The extracted data: This is the string to be signed.

}

chilkatExample();