DataFlex
Decrypt a govtalk.gov.uk SOAP GovTalkMessage

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

DataFlex
Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoXml
    String sBody
    Variant vCert
    Handle hoCert
    Handle hoCrypt
    Variant vBd
    Handle hoBd
    String sTemp1

    Move False To iSuccess

    // 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...

    Get Create (RefClass(cComChilkatXml)) To hoXml
    If (Not(IsComObjectCreated(hoXml))) Begin
        Send CreateComObject of hoXml
    End
    Get ComLoadXmlFile Of hoXml "qa_data/xml/govTalkMessageResponse.xml" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoXml To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComGetChildContent Of hoXml "Body|Message|Body" To sBody
    Showln sBody

    Get Create (RefClass(cComChilkatCert)) To hoCert
    If (Not(IsComObjectCreated(hoCert))) Begin
        Send CreateComObject of hoCert
    End
    Get ComLoadPfxFile Of hoCert "qa_data/pfx/govTalkMessage_aaa.pfx" "aaa" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoCert To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get Create (RefClass(cComChilkatCrypt2)) To hoCrypt
    If (Not(IsComObjectCreated(hoCrypt))) Begin
        Send CreateComObject of hoCrypt
    End
    Set ComCryptAlgorithm Of hoCrypt To "pki"
    Get pvComObject of hoCert to vCert
    Get ComSetDecryptCert Of hoCrypt vCert To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoCrypt To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get Create (RefClass(cComChilkatBinData)) To hoBd
    If (Not(IsComObjectCreated(hoBd))) Begin
        Send CreateComObject of hoBd
    End
    // Append the bytes to bd.
    Get ComAppendEncoded Of hoBd sBody "base64" To iSuccess

    // Decrypt in-place.
    Get pvComObject of hoBd to vBd
    Get ComDecryptBd Of hoCrypt vBd To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoCrypt To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Save the decrypted data to a file.
    Get ComWriteFile Of hoBd "qa_output/out.dat" To iSuccess

    // If the decrypted data is non-text (binary) then we can examine it in an encoding, such as hex:
    Get ComGetEncoded Of hoBd "hex" To sTemp1
    Showln "Decrypted bytes as hex: " sTemp1


End_Procedure