Delphi DLL
Calculate HRMC IRMark

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

Delphi DLL
uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Xml, XmlDSig, Crypt2;

...

procedure TForm1.Button1Click(Sender: TObject);
var
xml: HCkXml;
xdsig: HCkXmlDSig;
withComments: Boolean;
canonXml: PWideChar;
crypt: HCkCrypt2;
irmark: PWideChar;

begin
// 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>

Memo1.Lines.Add(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);

Memo1.Lines.Add('IRMark = ' + irmark);

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

end;