C++
Calculate HRMC IRMark

See more XML Digital Signatures Examples
Demonstrates how to calculate an IRmark for an HMRC GovTalkMessage XML document.
Chilkat C++ Downloads

C++
#include <CkXml.h>
#include <CkXmlDSig.h>
#include <CkCrypt2.h>

void ChilkatSample(void)
    {
    //  This example requires the Chilkat API to have been previously unlocked.
    //  See Global Unlock Sample for sample code.

    //  First build a sample (but incomplete) GovTalkMessage.
    //  You can replace this code with a call to LoadXml or LoadXmlFile..
    //  
    //  Note: The online tool at https://tools.chilkat.io/xmlCreate.cshtml
    //  can be used to generate XML code that creates a given XML document.
    CkXml xml;
    xml.put_Tag("GovTalkMessage");
    xml.AddAttribute("xmlns","http://www.govtalk.gov.uk/CM/envelope");
    xml.UpdateAttrAt("Body|Message",true,"xmlns","urn:g3.ge:dea:call:SendDocument:v1");
    xml.UpdateChildContent("Body|Message","................");

    //  This is the XML created:
    //  <?xml version="1.0" encoding="utf-8" ?>
    //  <GovTalkMessage xmlns="http://www.govtalk.gov.uk/CM/envelope">
    //      <Body>
    //          <Message xmlns="urn:g3.ge:dea:call:SendDocument:v1">................</Message>
    //      </Body>
    //  </GovTalkMessage>

    std::cout << xml.getXml() << "\r\n";

    //  Canonicalize the XML (using C14N)
    CkXmlDSig xdsig;
    bool withComments = false;
    const char *canonXml = xdsig.canonicalizeXml(xml.getXml(),"C14N",withComments);

    //  Return the base64 SHA-1 HASH of the canonical XML.
    CkCrypt2 crypt;
    crypt.put_HashAlgorithm("sha1");
    crypt.put_EncodingMode("base64");
    const char *irmark = crypt.hashStringENC(canonXml);

    std::cout << "IRMark = " << irmark << "\r\n";
    }