(Excel) Swift Alliance LAU XML Signature

Calculating the LAU for Swift Alliance File Act XML using HMAC SHA256. (The XML signature, also referred to as Local Authentication (LAU), is computed using the algorithm HMAC based on SHA-256.)

Download Excel Class Modules Chilkat Excel Class Modules

' This example assumes the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

' We begin with the following XML:

' <?xml version="1.0" encoding="UTF-8"?>
' <Saa:DataPDU xmlns:Saa="urn:swift:saa:xsd:saa.2.0" xmlns:Sw="urn:swift:snl:ns.Sw" xmlns:SwInt="urn:swift:snl:ns.SwInt" xmlns:SwGbl="urn:swift:snl:ns.SwGbl" xmlns:SwSec="urn:swift:snl:ns.SwSec">
'     <Saa:Revision>2.0.6</Saa:Revision>
'     <Saa:Header>
'         <Saa:Message>
'             <Saa:SenderReference>Ref760FA1234</Saa:SenderReference>
'             <Saa:MessageIdentifier>tsrv.fin.mt7xx.gteesstandbys</Saa:MessageIdentifier>
'             <Saa:Format>File</Saa:Format>
'             <Saa:SubFormat>Input</Saa:SubFormat>
'             <Saa:Sender>
'                 <Saa:DN>cn=su8,o=ptsqgbbb,o=swift</Saa:DN>
'                 <Saa:FullName>
'                     <Saa:X1>PTSQGBBBXXX</Saa:X1>
'                 </Saa:FullName>
'             </Saa:Sender>
'             <Saa:Receiver>
'                 <Saa:DN>cn=abc,ou=saa,o=xxx,o=swift</Saa:DN>
'                 <Saa:FullName>
'                     <Saa:X1>PTSXXXXXXXX</Saa:X1>
'                     <Saa:X2>saa</Saa:X2>
'                 </Saa:FullName>
'             </Saa:Receiver>
'             <Saa:InterfaceInfo>
'                 <Saa:UserReference>CRE...</Saa:UserReference>
'                 <Saa:MessageCreator>ApplicationInterface</Saa:MessageCreator>
'                 <Saa:MessageContext>Original</Saa:MessageContext>
'                 <Saa:MessageNature>Financial</Saa:MessageNature>
'             </Saa:InterfaceInfo>
'             <Saa:NetworkInfo>
'                 <Saa:Priority>Normal</Saa:Priority>
'                 <Saa:IsPossibleDuplicate>true</Saa:IsPossibleDuplicate>
'                 <Saa:Service>swift.corp.fast!x</Saa:Service>
'                 <Saa:Network>Application</Saa:Network>
'                 <Saa:SessionNr>0080</Saa:SessionNr>
'                 <Saa:SeqNr>000001</Saa:SeqNr>
'                 <Saa:SWIFTNetNetworkInfo>
'                     <Saa:RequestType>tsrv.fin.mt7xx.gteesstandbys</Saa:RequestType>
'                     <Saa:Reference>2f949999-d32e-49eb-9999-9a819b9b9c0d</Saa:Reference>
'                     <Saa:FileInfo>SwCompression=Zip</Saa:FileInfo>
'                 </Saa:SWIFTNetNetworkInfo>
'             </Saa:NetworkInfo>
'             <Saa:SecurityInfo>
'                 <Saa:SWIFTNetSecurityInfo>
'                     <Saa:FileDigestAlgorithm>SHA-256</Saa:FileDigestAlgorithm>
'                     <Saa:FileDigestValue>9tnnjIgsowPSU+ehm8Rb0J5TvZIvhCYnySzFkpur1aw=</Saa:FileDigestValue>
'                 </Saa:SWIFTNetSecurityInfo>
'             </Saa:SecurityInfo>
'             <Saa:FileLogicalName>Payload.ZIP</Saa:FileLogicalName>
'             <Saa:ExpiryDateTime>20210712074808</Saa:ExpiryDateTime>
'         </Saa:Message>
'     </Saa:Header>
'     <Saa:Body>Payload.ZIP</Saa:Body>
' </Saa:DataPDU>

' Load the XML file to be signed.
Dim sbXml As Chilkat.StringBuilder
Set sbXml = Chilkat.NewStringBuilder

success = sbXml.LoadFile("c:/someDir/fileToSign.xml","utf-8")
If (success = False) Then
    Debug.Print "Failed to load XML file."
    Exit Sub
End If

' We need to add a "LAU" XML element just before the "</Saa:DataPDU>"

numReplaced = sbXml.Replace("</Saa:DataPDU>","<LAU xmlns=""urn:swift:saa:xsd:saa.2.0""></LAU></Saa:DataPDU>")

Dim gen As Chilkat.XmlDSigGen
Set gen = Chilkat.NewXmlDSigGen
gen.SigLocation = "Saa:DataPDU|LAU"
gen.SigLocationMod = 0
gen.SigNamespacePrefix = "ds"
gen.SigNamespaceUri = "http://www.w3.org/2000/09/xmldsig#"
gen.SignedInfoCanonAlg = "EXCL_C14N"
gen.SignedInfoDigestMethod = "sha256"
gen.Behaviors = "CompactSignedXml"

' Sign the entire document.
Dim success As Boolean
success = gen.AddSameDocRef("","sha256","EXCL_C14N","","")

' Set our HMAC key
success = gen.SetHmacKey("Abcdef0123456789Abcdef0123456789","ascii")

' Sign the XML:
success = gen.CreateXmlDSigSb(sbXml)
If (success = False) Then
    Debug.Print gen.LastErrorText
    Exit Sub
End If

' Examine the signed XML
Debug.Print sbXml.GetAsString()

' Save the signed XML to a file.
success = sbXml.WriteFile("c:/someDir/signedFile.xml","utf-8",False)