(Node.js) Decrypt a govtalk.gov.uk SOAP GovTalkMessage

Demonstrates how to decrypt the content contained in the XML of a GovTalkMessage SOAP response.

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() {

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

    // The GovTalkMessage response looks something like this:

    // <?xml version="1.0" encoding="utf-8"?>
    // <GovTalkMessage xmlns="http://www.govtalk.gov.uk/CM/envelope">
    //   <EnvelopeVersion>3.1</EnvelopeVersion>
    //   <Header>
    //     <MessageDetails>
    //       <Class>CSSZ_DZDPN</Class>
    //       <Qualifier>request</Qualifier>
    //       <Function>submit</Function>
    //       <TransactionID />
    //       <AuditID />
    //       <CorrelationID>aaaaa</CorrelationID>
    //       <ResponseEndPoint PollInterval="0" />
    //       <Transformation>XML</Transformation>
    //       <GatewayTest />
    //       <GatewayTimestamp />
    //     </MessageDetails>
    //     <SenderDetails>
    //       <IDAuthentication>
    //         <SenderID />
    //         <Authentication>
    //           <Method>clear</Method>
    //           <Role />
    //           <Value />
    //         </Authentication>
    //       </IDAuthentication>
    //       <X509Certificate />
    //       <EmailAddress>somebody@example.com</EmailAddress>
    //     </SenderDetails>
    //   </Header>
    //   <GovTalkDetails>
    //     <Keys>
    //       <Key Type="vars">9999999999</Key>
    //     </Keys>
    //     <GatewayAdditions>
    //       <Source>VREP</Source>
    //     </GatewayAdditions>
    //   </GovTalkDetails>
    //   <Body>
    //     <Message xmlns="http://www.cssz.cz/XMLSchema/envelope" version="1.2" eType="DZDPN20">
    //       <Header>
    //         <Signature xmlns:dt="urn:schemas-microsoft-com:datatypes" dt:dt="bin.base64">MIIJ0A ... UMw=
    // </Signature>
    //         <Vendor productName="some product name" version="2019" />
    //       </Header>
    //       <Body xmlns:dt="urn:schemas-microsoft-com:datatypes" encrypted="yes" contentEncoding="gzip" dt:dt="bin.base64">MIIF2w ... N2vW</Body>
    //     </Message>
    //   </Body>
    // </GovTalkMessage>

    // We want to get the content of the Body and decrypt it.

    // First, let's get the content of the Body XML element, which is a base64 string starting with MIIF2w...

    var xml = new chilkat.Xml();
    var success = xml.LoadXmlFile("qa_data/xml/govTalkMessageResponse.xml");
    if (success == false) {
        console.log(xml.LastErrorText);
        return;
    }

    var Body = xml.GetChildContent("Body|Message|Body");
    console.log(Body);

    var cert = new chilkat.Cert();
    success = cert.LoadPfxFile("qa_data/pfx/govTalkMessage_aaa.pfx","aaa");
    if (success == false) {
        console.log(cert.LastErrorText);
        return;
    }

    var crypt = new chilkat.Crypt2();
    crypt.CryptAlgorithm = "pki";
    success = crypt.SetDecryptCert(cert);
    if (success == false) {
        console.log(crypt.LastErrorText);
        return;
    }

    var bd = new chilkat.BinData();
    // Append the bytes to bd.
    success = bd.AppendEncoded(Body,"base64");

    // Decrypt in-place.
    success = crypt.DecryptBd(bd);
    if (success == false) {
        console.log(crypt.LastErrorText);
        return;
    }

    // Save the decrypted data to a file.
    success = bd.WriteFile("qa_output/out.dat");

    // If the decrypted data is non-text (binary) then we can examine it in an encoding, such as hex:
    console.log("Decrypted bytes as hex: " + bd.GetEncoded("hex"));

}

chilkatExample();