(PHP Extension) Decrypt a govtalk.gov.uk SOAP GovTalkMessage

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

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<?php

// The version number (9_5_0) should match version of the Chilkat extension used, omitting the micro-version number.
// For example, if using Chilkat v9.5.0.48, then include as shown here:
include("chilkat_9_5_0.php");

// 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...

$xml = new CkXml();
$success = $xml->LoadXmlFile('qa_data/xml/govTalkMessageResponse.xml');
if ($success == false) {
    print $xml->lastErrorText() . "\n";
    exit;
}

$Body = $xml->getChildContent('Body|Message|Body');
print $Body . "\n";

$cert = new CkCert();
$success = $cert->LoadPfxFile('qa_data/pfx/govTalkMessage_aaa.pfx','aaa');
if ($success == false) {
    print $cert->lastErrorText() . "\n";
    exit;
}

$crypt = new CkCrypt2();
$crypt->put_CryptAlgorithm('pki');
$success = $crypt->SetDecryptCert($cert);
if ($success == false) {
    print $crypt->lastErrorText() . "\n";
    exit;
}

$bd = new CkBinData();
// Append the bytes to bd.
$success = $bd->AppendEncoded($Body,'base64');

// Decrypt in-place.
$success = $crypt->DecryptBd($bd);
if ($success == false) {
    print $crypt->lastErrorText() . "\n";
    exit;
}

// 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:
print 'Decrypted bytes as hex: ' . $bd->getEncoded('hex') . "\n";

?>