Calculate HRMC IRMark

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

#include <C_CkXml.h>
#include <C_CkXmlDSig.h>
#include <C_CkCrypt2.h>

void ChilkatSample(void)
    {
    HCkXml xml;
    HCkXmlDSig xdsig;
    BOOL withComments;
    const char *canonXml;
    HCkCrypt2 crypt;
    const char *irmark;

    // 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.
    xml = CkXml_Create();
    CkXml_putTag(xml,"GovTalkMessage");
    CkXml_AddAttribute(xml,"xmlns","http://www.govtalk.gov.uk/CM/envelope");
    CkXml_UpdateAttrAt(xml,"Body|Message",TRUE,"xmlns","urn:g3.ge:dea:call:SendDocument:v1");
    CkXml_UpdateChildContent(xml,"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>

    printf("%s\n",CkXml_getXml(xml));

    // Canonicalize the XML (using C14N)
    xdsig = CkXmlDSig_Create();
    withComments = FALSE;
    canonXml = CkXmlDSig_canonicalizeXml(xdsig,CkXml_getXml(xml),"C14N",withComments);

    // Return the base64 SHA-1 HASH of the canonical XML.
    crypt = CkCrypt2_Create();
    CkCrypt2_putHashAlgorithm(crypt,"sha1");
    CkCrypt2_putEncodingMode(crypt,"base64");
    irmark = CkCrypt2_hashStringENC(crypt,canonXml);

    printf("IRMark = %s\n",irmark);


    CkXml_Dispose(xml);
    CkXmlDSig_Dispose(xdsig);
    CkCrypt2_Dispose(crypt);

    }