(Tcl) Create XML Digital Signature using Certificate on Smart Card

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Demonstrates how to load a certificate located on a smart card or USB token and then use it for creating an XML digital signature such that the cryptographic signing happens on the smart card.

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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.

set scmd [new_CkScMinidriver]

# Reader names (smart card readers or USB tokens) can be discovered
# via List Readers or Find Smart Cards
set readerName "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0"
set success [CkScMinidriver_AcquireContext $scmd $readerName]
if {$success == 0} then {
    puts [CkScMinidriver_lastErrorText $scmd]
    delete_CkScMinidriver $scmd
    exit
}

# If successful, the name of the currently inserted smart card is available:
puts "Card name: [CkScMinidriver_cardName $scmd]"

# If desired, perform regular PIN authentication with the smartcard.
# For more details about smart card PIN authentication, see the Smart Card PIN Authentication Example
set retval [CkScMinidriver_PinAuthenticate $scmd "user" "000000"]
if {$retval != 0} then {
    puts "PIN Authentication failed."
}

# You can find a cerficate using any of the following certificate parts:
# "subjectDN" -- The full distinguished name of the cert.
# "subjectDN_withTags" -- Same as above, but in a format that includes the subject part tags, such as the "CN=" in "CN=something"
# "subjectCN" -- The common name part (CN) of the certificate's subject.
# "serial" -- The certificate serial number.
# "serial:issuerCN" -- The certificate serial number + the issuer's common name, delimited with a colon char.
# These are the same certificate parts that can be retrieved by listing certificates on the smart card (or USB token).
# See List Certificates on Smart Card Example
set certPart "subjectCN"
set partValue "PIVKey E42D60A759D39147A26E0AF2FB1183C5"

# If the certificate is found, it is loaded into the cert object.
set cert [new_CkCert]

set success [CkScMinidriver_FindCert $scmd $certPart $partValue $cert]
if {$success == 0} then {
    puts "Failed to find the certificate."
    CkScMinidriver_DeleteContext $scmd
    delete_CkScMinidriver $scmd
    delete_CkCert $cert
    exit
}

puts "Successfully loaded the cert object from the smart card / USB token."

# Note: When successful, the cert object is internally linked to the ScMinidriver object's authenticated session.
# The cert object can now be used to sign or do other cryptographic operations that occur on the smart card / USB token.
# If your application calls PinDeauthenticate or DeleteContext, the cert will no longer be able to sign on the smart card
# because the smart card ScMinidriver session will no longer be authenticated or deleted.

# ------------------------------------------------------------------------------------------------------------
# We have the certificate.  Now let's do the XML digital signature..

# Create the following XML to be signed:

# <?xml version="1.0" encoding="UTF-8" standalone="no" ?>
# <SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
#     <SOAP-ENV:Header>
#         <wsse:Security xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd" SOAP-ENV:mustUnderstand="1"></wsse:Security>
#     </SOAP-ENV:Header>
#     <SOAP-ENV:Body xmlns:SOAP-SEC="http://schemas.xmlsoap.org/soap/security/2000-12" SOAP-SEC:id="Body">
#         <z:FooBar xmlns:z="http://example.com" />
#     </SOAP-ENV:Body>
# </SOAP-ENV:Envelope>

set xml [new_CkXml]

CkXml_put_Tag $xml "SOAP-ENV:Envelope"
CkXml_AddAttribute $xml "xmlns:SOAP-ENV" "http://schemas.xmlsoap.org/soap/envelope/"
CkXml_UpdateAttrAt $xml "SOAP-ENV:Header|wsse:Security" 1 "xmlns:wsse" "http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd"
CkXml_UpdateAttrAt $xml "SOAP-ENV:Header|wsse:Security" 1 "SOAP-ENV:mustUnderstand" "1"
CkXml_UpdateAttrAt $xml "SOAP-ENV:Body" 1 "xmlns:SOAP-SEC" "http://schemas.xmlsoap.org/soap/security/2000-12"
CkXml_UpdateAttrAt $xml "SOAP-ENV:Body" 1 "SOAP-SEC:id" "Body"
CkXml_UpdateAttrAt $xml "SOAP-ENV:Body|z:FooBar" 1 "xmlns:z" "http://example.com"

# Prepare for signing...
set gen [new_CkXmlDSigGen]

# Indicate where the Signature will be inserted.
CkXmlDSigGen_put_SigLocation $gen "SOAP-ENV:Envelope|SOAP-ENV:Header|wsse:Security"

# Add a reference to the fragment of the XML to be signed.

# Note: "Body" refers to the XML element having an "id" equal to "Body", where "id" is case insensitive
# and where any namespace might qualify the attribute.  In this case, the SOAP-ENV:Body fragment is signed
# NOT because the tag = "Body", but because it has SOAP-SEC:id="Body"
CkXmlDSigGen_AddSameDocRef $gen "Body" "sha1" "EXCL_C14N" "" ""

# (You can read about the SignedInfoPrefixList in the online reference documentation.  It's optional..)
CkXmlDSigGen_put_SignedInfoPrefixList $gen "wsse SOAP-ENV"

# Provide the private key for signing via the certificate, and indicate that
# we want the base64 of the certificate embedded in the KeyInfo.
CkXmlDSigGen_put_KeyInfoType $gen "X509Data"
CkXmlDSigGen_put_X509Type $gen "Certificate"

# Note: Our certificate was loaded from the smartcard and is internally linked to the authenticated ScMinidriver session.
# The signing will occur on the smart card using the chosen certificate.
set bUsePrivateKey 1
set success [CkXmlDSigGen_SetX509Cert $gen $cert $bUsePrivateKey]
if {$success != 1} then {
    puts [CkXmlDSigGen_lastErrorText $gen]
    delete_CkScMinidriver $scmd
    delete_CkCert $cert
    delete_CkXml $xml
    delete_CkXmlDSigGen $gen
    exit
}

# Everything's specified.  Now create and insert the Signature
set sbXml [new_CkStringBuilder]

CkXml_GetXmlSb $xml $sbXml
set success [CkXmlDSigGen_CreateXmlDSigSb $gen $sbXml]
if {$success != 1} then {
    puts [CkXmlDSigGen_lastErrorText $gen]
    delete_CkScMinidriver $scmd
    delete_CkCert $cert
    delete_CkXml $xml
    delete_CkXmlDSigGen $gen
    delete_CkStringBuilder $sbXml
    exit
}

# Examine the XML with the digital signature inserted
puts [CkStringBuilder_getAsString $sbXml]

# ------------------------------------------------------------------------------------------------------------
# Cleanup our ScMinidriver session...

# When finished with operations that required authentication, you may if you wish, deauthenticate the session.
set success [CkScMinidriver_PinDeauthenticate $scmd "user"]
if {$success == 0} then {
    puts [CkScMinidriver_lastErrorText $scmd]
}

# Delete the context when finished with the card.
set success [CkScMinidriver_DeleteContext $scmd]
if {$success == 0} then {
    puts [CkScMinidriver_lastErrorText $scmd]
}


delete_CkScMinidriver $scmd
delete_CkCert $cert
delete_CkXml $xml
delete_CkXmlDSigGen $gen
delete_CkStringBuilder $sbXml