(Tcl) 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.)

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load ./chilkat.dll

# 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.
set sbXml [new_CkStringBuilder]

set success [CkStringBuilder_LoadFile $sbXml "c:/someDir/fileToSign.xml" "utf-8"]
if {$success == 0} then {
    puts "Failed to load XML file."
    delete_CkStringBuilder $sbXml
    exit
}

# We need to add a "LAU" XML element just before the "</Saa:DataPDU>"
set numReplaced [CkStringBuilder_Replace $sbXml "</Saa:DataPDU>" "<LAU xmlns=\"urn:swift:saa:xsd:saa.2.0\"></LAU></Saa:DataPDU>"]

set gen [new_CkXmlDSigGen]

CkXmlDSigGen_put_SigLocation $gen "Saa:DataPDU|LAU"
CkXmlDSigGen_put_SigLocationMod $gen 0
CkXmlDSigGen_put_SigNamespacePrefix $gen "ds"
CkXmlDSigGen_put_SigNamespaceUri $gen "http://www.w3.org/2000/09/xmldsig#"
CkXmlDSigGen_put_SignedInfoCanonAlg $gen "EXCL_C14N"
CkXmlDSigGen_put_SignedInfoDigestMethod $gen "sha256"
CkXmlDSigGen_put_Behaviors $gen "CompactSignedXml"

# Sign the entire document.
CkXmlDSigGen_AddSameDocRef $gen "" "sha256" "EXCL_C14N" "" ""

# Set our HMAC key
CkXmlDSigGen_SetHmacKey $gen "Abcdef0123456789Abcdef0123456789" "ascii"

# Sign the XML:
set success [CkXmlDSigGen_CreateXmlDSigSb $gen $sbXml]
if {$success == 0} then {
    puts [CkXmlDSigGen_lastErrorText $gen]
    delete_CkStringBuilder $sbXml
    delete_CkXmlDSigGen $gen
    exit
}

# Examine the signed XML
puts [CkStringBuilder_getAsString $sbXml]

# Save the signed XML to a file.
set success [CkStringBuilder_WriteFile $sbXml "c:/someDir/signedFile.xml" "utf-8" 0]

delete_CkStringBuilder $sbXml
delete_CkXmlDSigGen $gen