(Ruby) 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.)

Chilkat Ruby Downloads install from rubygems.org gem install chilkat or download... Ruby Library for Windows, MacOS, Linux, Alpine Linux

require 'chilkat'

# 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.
sbXml = Chilkat::CkStringBuilder.new()
success = sbXml.LoadFile("c:/someDir/fileToSign.xml","utf-8")
if (success == false)
    print "Failed to load XML file." + "\n";
    exit
end

# 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>")

gen = Chilkat::CkXmlDSigGen.new()
gen.put_SigLocation("Saa:DataPDU|LAU")
gen.put_SigLocationMod(0)
gen.put_SigNamespacePrefix("ds")
gen.put_SigNamespaceUri("http://www.w3.org/2000/09/xmldsig#")
gen.put_SignedInfoCanonAlg("EXCL_C14N")
gen.put_SignedInfoDigestMethod("sha256")
gen.put_Behaviors("CompactSignedXml")

# Sign the entire document.
gen.AddSameDocRef("","sha256","EXCL_C14N","","")

# Set our HMAC key
gen.SetHmacKey("Abcdef0123456789Abcdef0123456789","ascii")

# Sign the XML:
success = gen.CreateXmlDSigSb(sbXml)
if (success == false)
    print gen.lastErrorText() + "\n";
    exit
end

# Examine the signed XML
print sbXml.getAsString() + "\n";

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