(Tcl) Create XML Digital Signature using a ECDSA Key

Demonstrates how to create an XML digital signature using a ECDSA key.

This example requires Chilkat v9.5.0.69 or greater.

Chilkat Tcl Extension Downloads Chilkat Tcl Extension Downloads

load ./chilkat.dll

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

# The SOAP XML to be signed in this example contains the following:

# <?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>
# 

# The above XML is available at https://www.chilkatsoft.com/exampleData/soapToSign.xml
# Fetch the XML and then sign it..

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

set sbSoapXml [new_CkStringBuilder]

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

# This example uses an ECDSA private key for signing.  
# There are many ways to load an ECDSA private key using Chilkat.  This example
# will load from an unencrypted PEM file.

# For your convenience, Chilkat put this sample ECDSA PEM here:  https://www.chilkatsoft.com/exampleData/secp256r1-key.zip
set ecKey [new_CkPrivateKey]

set success [CkPrivateKey_LoadPemFile $ecKey "qa_data/ecc/secp256r1-key.pem"]
if {$success != 1} then {
    puts [CkPrivateKey_lastErrorText $ecKey]
    delete_CkHttp $http
    delete_CkStringBuilder $sbSoapXml
    delete_CkPrivateKey $ecKey
    exit
}

# To create the XML digital signature (i.e. embed the signature within
# the SOAP XML), we specify what is desired, and then call the method to 
# create the XML signature.
# 
# For example, the application must provide the following:
#     - Where to put the signature.
#     - What to sign.
#     - The algorithms to be used.
#     - The key to be used for signing.
# 

set xmlSigGen [new_CkXmlDSigGen]

# In this example, the Signature will be placed within the wsse:Security element.
# To specify the location, set the SigLocation property to the XML path to this element,
# using vertical bar characters to separate tags.
CkXmlDSigGen_put_SigLocation $xmlSigGen "SOAP-ENV:Envelope|SOAP-ENV:Header|wsse:Security"

# An XML digital signature contains one or more references.  A given reference
# can be a same-document reference (to an XML fragment), or an external reference.
# This example will add a single same-document reference.  We'll add a reference to the XML fragment
# at SOAP-ENV:Body, which is indicated by providing the value of the "Id" attribute (where "Id" is case
# insensitive).  For each same-document reference, we must also indicate the hash algorithm and XML canonicalization
# algorithm to be used.  For this example we'll choose SHA-256 and Exclusive XML Canonicalization.
CkXmlDSigGen_AddSameDocRef $xmlSigGen "Body" "sha256" "EXCL_C14N" "" ""

# Let's provide the ECDSA key to be used for signing:
CkXmlDSigGen_SetPrivateKey $xmlSigGen $ecKey

# We're leaving the following properties at their default values:
# 
#    - SigNamespacePrefix (default is "ds")
#    - SignedInfoCanonAlg  (default is EXCL_C14N)
#    - SignedInfoDigestMethod (default is sha256)
#    - KeyInfoType (default is "KeyValue", where the ECDSA public key is included in the Signature)

# Note: Each Reference specifies its own algorithms for XML canonicalization and hashing.
# The SignedInfo part also has specified hash and canonicalization algorithms, which may be different
# than the algorithms used in the References.
# In this example, we use Exclusive XML Canonicalization and SHA-256 throughout.

# Finally, we're going to set one property that's optional, but commonly used.
# It's the SignedInfoPrefixList.  In this case, we're using Exclusive Canonicalization, and the signature
# will be placed in a location within the XML document where namespace prefixes are used in the ancestors.
# Specifically, the "wsse" and "SOAP-ENV" namespace prefixes are used.
CkXmlDSigGen_put_SignedInfoPrefixList $xmlSigGen "wsse SOAP-ENV"

# OK, everything's specified, so let's create the XML digital signature:
# This in-place signs the XML.  If successful, sbSoapXml will contain the 
# XML with the digital signature at the specified location.
set success [CkXmlDSigGen_CreateXmlDSigSb $xmlSigGen $sbSoapXml]
if {$success != 1} then {
    puts [CkXmlDSigGen_lastErrorText $xmlSigGen]
    delete_CkHttp $http
    delete_CkStringBuilder $sbSoapXml
    delete_CkPrivateKey $ecKey
    delete_CkXmlDSigGen $xmlSigGen
    exit
}

# Examine the signed SOAP XML:
puts [CkStringBuilder_getAsString $sbSoapXml]

# This is the signed SOAP XML.
# Chilkat emits the Signature in compact form on a single line.  Whitespace in XML signatures
# matters.  Chilkat's opinion is that writing the Signature without whitespace minimizes the chance
# for problems with whatever software might be verifying the signature.

# <?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"><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#"><InclusiveNamespaces xmlns="http://www.w3.org/2001/10/xml-exc-c14n#" PrefixList="wsse SOAP-ENV"/></ds:CanonicalizationMethod><ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha256"/><ds:Reference URI="#Body"><ds:Transforms><ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/></ds:Transforms><ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/><ds:DigestValue>OwgHPZNfDkXnZsjpfzXqAcT3RV3HzmTsEy2bP44FJ0M=</ds:DigestValue></ds:Reference></ds:SignedInfo><ds:SignatureValue>jmPSGgtirHSjjcs/o0NIDwwvy4aFBCEosSN+XP5NLVuGpRYnS2EM7mItiw6TKmESAoJYV23ZN4pZ9BFRKSvZqw==</ds:SignatureValue><ds:KeyInfo><ds:KeyValue><ds:ECKeyValue xmlns="http://www.w3.org/2009/xmldsig11#"><ds:NamedCurve URI="urn:oid:1.2.840.10045.3.1.7" /><ds:PublicKey>BOVKaiLPKEDChhkA64UEBOXTv/VFHnhrUPN+bXqCvEl7rroAYpH5tKzbiGTtMSlp4JO9Pxg44zeX7EoWDvOrpD0=</ds:PublicKey></ds:ECKeyValue></ds:KeyValue></ds:KeyInfo></ds:Signature></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>

# The above signed XML contains the ECDSA public key in the ECKeyValue fragment (within the ds:KeyInfo).
# The signature can easily be verified like this:

set verifier [new_CkXmlDSig]

# First load the XML containing the signature(s) to be verified.
set success [CkXmlDSig_LoadSignatureSb $verifier $sbSoapXml]
if {$success != 1} then {
    puts [CkXmlDSig_lastErrorText $verifier]
    delete_CkHttp $http
    delete_CkStringBuilder $sbSoapXml
    delete_CkPrivateKey $ecKey
    delete_CkXmlDSigGen $xmlSigGen
    delete_CkXmlDSig $verifier
    exit
}

set bVerified [CkXmlDSig_VerifySignature $verifier 1]
if {$bVerified != 1} then {
    puts [CkXmlDSig_lastErrorText $verifier]
}

puts "Signature verified = $bVerified"

delete_CkHttp $http
delete_CkStringBuilder $sbSoapXml
delete_CkPrivateKey $ecKey
delete_CkXmlDSigGen $xmlSigGen
delete_CkXmlDSig $verifier