(Xojo Plugin) Decrypt a govtalk.gov.uk SOAP GovTalkMessage

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

Chilkat Xojo Plugin Download

Xojo Plugin for Windows, Linux, Mac OS X, and ARM, ARM64

// 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...

Dim xml As New Chilkat.Xml
Dim success As Boolean
success = xml.LoadXmlFile("qa_data/xml/govTalkMessageResponse.xml")
If (success = False) Then
    System.DebugLog(xml.LastErrorText)
    Return
End If

Dim Body As String
Body = xml.GetChildContent("Body|Message|Body")
System.DebugLog(Body)

Dim cert As New Chilkat.Cert
success = cert.LoadPfxFile("qa_data/pfx/govTalkMessage_aaa.pfx","aaa")
If (success = False) Then
    System.DebugLog(cert.LastErrorText)
    Return
End If

Dim crypt As New Chilkat.Crypt2
crypt.CryptAlgorithm = "pki"
success = crypt.SetDecryptCert(cert)
If (success = False) Then
    System.DebugLog(crypt.LastErrorText)
    Return
End If

Dim bd As New Chilkat.BinData
// Append the bytes to bd.
success = bd.AppendEncoded(Body,"base64")

// Decrypt in-place.
success = crypt.DecryptBd(bd)
If (success = False) Then
    System.DebugLog(crypt.LastErrorText)
    Return
End If

// 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:
System.DebugLog("Decrypted bytes as hex: " + bd.GetEncoded("hex"))