(Excel) Calculate HRMC IRMark

Demonstrates how to calculate an IRmark for an HMRC GovTalkMessage XML document.

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'  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.
Dim xml As Chilkat.Xml
Set xml = Chilkat.NewXml
xml.Tag = "GovTalkMessage"
Dim success As Boolean
success = xml.AddAttribute("xmlns","http://www.govtalk.gov.uk/CM/envelope")
success = 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>

Debug.Print xml.GetXml()

'  Canonicalize the XML (using C14N)
Dim xdsig As Chilkat.XmlDSig
Set xdsig = Chilkat.NewXmlDSig

withComments = False

canonXml = xdsig.CanonicalizeXml(xml.GetXml(),"C14N",withComments)

'  Return the base64 SHA-1 HASH of the canonical XML.
Dim crypt As Chilkat.Crypt2
Set crypt = Chilkat.NewCrypt2
crypt.HashAlgorithm = "sha1"
crypt.EncodingMode = "base64"

irmark = crypt.HashStringENC(canonXml)

Debug.Print "IRMark = "; irmark