(Tcl) Verify HMAC XML Digital Signature

Demonstrates how to validate an XML digital signature signed with an HMAC key.

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load ./chilkat.dll

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

# The XML containing the Signature to be verified contains the following:

# <?xml version="1.0" encoding="UTF-8" standalone="no"?>
# <collection Id="root">
# 	<album>
# 		<title>Questions, unanswered</title>
# 		<artist>Steve and the flubberblubs</artist>
# 		<year>1989</year>
# 		<t:tracks xmlns:t="http://test.xades4j/tracks">
# 			<t:song length="4:05" tracknumber="1">
# 				<t:title>What do you know?</t:title>
# 				<t:artist>Steve and the flubberblubs</t:artist>
# 				<t:lastplayed>2006-10-17-08:31</t:lastplayed>
# 			</t:song>
# 			<t:song length="3:45" tracknumber="2">
# 				<t:title>Who do you know?</t:title>
# 				<t:artist>Steve and the flubberblubs</t:artist>
# 				<t:lastplayed>2006-10-17-08:35</t:lastplayed>
# 			</t:song>
# 			<t:song length="5:14" tracknumber="3">
# 				<t:title>When do you know?</t:title>
# 				<t:artist>Steve and the flubberblubs</t:artist>
# 				<t:lastplayed>2006-10-17-08:39</t:lastplayed>
# 			</t:song>
# 			<t:song length="4:19" tracknumber="4">
# 				<t:title>Do you know?</t:title>
# 				<t:artist>Steve and the flubberblubs</t:artist>
# 				<t:lastplayed>2006-10-17-08:44</t:lastplayed>
# 			</t:song>
# 		</t:tracks>
# 	</album>
# <ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#"><ds:SignedInfo><ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/><ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#hmac-sha256"/><ds:Reference URI="#root"><ds:Transforms><ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/></ds:Transforms><ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/><ds:DigestValue>rD/g8soqKz8EiPUBhEWfcQacS0ta4ULHX3dKMEH6ZoQ=</ds:DigestValue></ds:Reference></ds:SignedInfo><ds:SignatureValue>R8dXP95VRYJBfL6d0Peogybdk27+R+JIfX8jnVu0NOI=</ds:SignatureValue></ds:Signature></collection>

# The above XML is available at https://www.chilkatsoft.com/exampleData/hmacSigned.xml
# First fetch the XML..

set url "https://www.chilkatsoft.com/exampleData/hmacSigned.xml"
set http [new_CkHttp]

set sbXml [new_CkStringBuilder]

set success [CkHttp_QuickGetSb $http $url $sbXml]
if {$success != 1} then {
    puts [CkHttp_lastErrorText $http]
    delete_CkHttp $http
    delete_CkStringBuilder $sbXml
    exit
}

set verifier [new_CkXmlDSig]

# Load the XML containing the signature to be verified.
set success [CkXmlDSig_LoadSignatureSb $verifier $sbXml]
if {$success != 1} then {
    puts [CkXmlDSig_lastErrorText $verifier]
    delete_CkHttp $http
    delete_CkStringBuilder $sbXml
    delete_CkXmlDSig $verifier
    exit
}

# Provide the HMAC key
# The HMAC key for this signature is the us-ascii bytes of the string "secret",
# It can be set in any of the following ways (and also more ways not shown here..)
CkXmlDSig_SetHmacKey $verifier "secret" "ascii"
# or
CkXmlDSig_SetHmacKey $verifier "c2VjcmV0" "base64"
# or
CkXmlDSig_SetHmacKey $verifier "736563726574" "hex"

# Verify the signature
set bVerified [CkXmlDSig_VerifySignature $verifier 1]
puts "Signature verified = $bVerified"

delete_CkHttp $http
delete_CkStringBuilder $sbXml
delete_CkXmlDSig $verifier