Tcl

Verify an XML Signature with Multiple References

See more XML Digital Signatures Examples

Demonstrates how to verify an XML digital signature that contains multiple references. Tcl

load ./chilkat.dll

set success 0

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

# An example of an enveloping XML signature with mulitple references is available at
# https://www.chilkatsoft.com/exampleData/envelopedMultipleRefs.xml

# This example will show how to verify the signature and all references, and also how
# to verify each reference individually.  This is useful to distinguish which part
# of the XML signature validation failed.  It could be that one or more of the references
# failed because of a hash computation mismatch.  Or it could be that the signature over
# the SignedInfo failed.  

# First, let's grab the sample XML signature.
set http [new_CkHttp]

set sbXml [new_CkStringBuilder]

set success [CkHttp_QuickGetSb $http "https://www.chilkatsoft.com/exampleData/envelopedMultipleRefs.xml" $sbXml]
if {$success != 1} then {
    puts [CkHttp_lastErrorText $http]
    delete_CkHttp $http
    delete_CkStringBuilder $sbXml
    exit
}

# Load the XML containing the signature to be verified.
set verifier [new_CkXmlDSig]

set success [CkXmlDSig_LoadSignatureSb $verifier $sbXml]
if {$success != 1} then {
    puts [CkXmlDSig_lastErrorText $verifier]
    delete_CkHttp $http
    delete_CkStringBuilder $sbXml
    delete_CkXmlDSig $verifier
    exit
}

set verifyReferenceDigests 1

# The quick way to validate all references and the signature over the SignedInfo
# is to call VerifySignature with verifyReferenceDigests equal to 1.
set verified [CkXmlDSig_VerifySignature $verifier $verifyReferenceDigests]
puts "Signature and all reference digests verified = $verified"

# Let's pretend the call to VerifySignature returned 0.  Something did not validate.
# Was it one or more of the References that did not hash to the correct value?
# Or was it the signature over the SignedInfo that failed?
# We can check just the signature over the SignedInfo by passing 0 to VerifySignature.
# This allows us to skip the hashing and checking each Reference.  
set verifyReferenceDigests 0
set signedInfoVerified [CkXmlDSig_VerifySignature $verifier $verifyReferenceDigests]
puts "Neglecting the reference hashes, the SignedInfo validation result = $signedInfoVerified"

# We can also verify each reference digest separately
set numRefs [CkXmlDSig_get_NumReferences $verifier]
set i 0
while {$i < $numRefs} {
    set refDigestVerified [CkXmlDSig_VerifyReferenceDigest $verifier $i]
    puts "Reference $i digest verified = $refDigestVerified"
    set i [expr $i + 1]
}

# For this sample XML signature with 3 References, we get the following output:

# Signature and all reference digests verified = True
# Neglecting the reference hashes, the SignedInfo validation result = True
# Reference 0 digest verified = True
# Reference 1 digest verified = True
# Reference 2 digest verified = Tru

delete_CkHttp $http
delete_CkStringBuilder $sbXml
delete_CkXmlDSig $verifier