(Ruby) SAML Signature Validation

See more XML Digital Signatures Examples

A SAML Signature is an XML Digital Signature (XMLDSig) just like any other XML digital signature. It can be verified by using Chilkat' XmlDSig class, as shown in this example.

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

require 'chilkat'

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

dsig = Chilkat::CkXmlDSig.new()
success = dsig.LoadSignature("XML xml signature goes here...")

# A sample SAML signature is shown below..

numSignatures = dsig.get_NumSignatures()
i = 0
while i < numSignatures
    dsig.put_Selector(i)

    bVerifyRefDigests = false
    bSignatureVerified = dsig.VerifySignature(bVerifyRefDigests)
    if (bSignatureVerified == true)
        print "Signature " + (i + 1).to_s() + " verified" + "\n";
    else
        print "Signature " + (i + 1).to_s() + " invalid" + "\n";
    end

    # Check each of the reference digests separately..
    numRefDigests = dsig.get_NumReferences()
    j = 0
    while j < numRefDigests
        bDigestVerified = dsig.VerifyReferenceDigest(j)
        print "reference digest " + (j + 1).to_s() + " verified = " + bDigestVerified.to_s() + "\n";
        if (bDigestVerified == false)
            print "    reference digest fail reason: " + dsig.get_RefFailReason().to_s() + "\n";
        end

        j = j + 1
    end

    i = i + 1
end

# --------------------------------------
# Here is a sample SAML XML Signature
# 
# 
# <?xml version="1.0" encoding="UTF-8"?>
# <saml2p:Response xmlns:saml2p="urn:oasis:names:tc:SAML:2.0:protocol" ID="abc123" Version="2.0" IssueInstant="2022-04-01T12:34:56Z" Destination="https://sp.example.com/sso">
#   <saml2:Issuer xmlns:saml2="urn:oasis:names:tc:SAML:2.0:assertion">https://idp.example.com</saml2:Issuer>
#   <saml2p:Status>
#     <saml2p:StatusCode Value="urn:oasis:names:tc:SAML:2.0:status:Success"/>
#   </saml2p:Status>
#   <saml2:Assertion xmlns:saml2="urn:oasis:names:tc:SAML:2.0:assertion" ID="def456" IssueInstant="2022-04-01T12:34:56Z" Version="2.0">
#     <saml2:Issuer>https://idp.example.com</saml2:Issuer>
#     <saml2:Subject>
#       <saml2:NameID Format="urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress">user@example.com</saml2:NameID>
#     </saml2:Subject>
#     <saml2:Conditions NotBefore="2022-04-01T12:34:56Z" NotOnOrAfter="2022-04-01T13:34:56Z"/>
#     <saml2:AuthnStatement AuthnInstant="2022-04-01T12:34:56Z">
#       <saml2:AuthnContext>
#         <saml2:AuthnContextClassRef>urn:oasis:names:tc:SAML:2.0:ac:classes:Password</saml2:AuthnContextClassRef>
#       </saml2:AuthnContext>
#     </saml2:AuthnStatement>
#     <!-- Additional assertion content -->
#   </saml2:Assertion>
#   <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#rsa-sha256"/>
#       <ds:Reference URI="#abc123">
#         <ds:Transforms>
#           <ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/>
#           <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>q7Zj1w+...+pCsjw=</ds:DigestValue>
#       </ds:Reference>
#       <!-- Additional references if present -->
#     </ds:SignedInfo>
#     <ds:SignatureValue>
#       NjIzOWE5ZjA2M2M1...NzUwNzUwNzUwNzUwNzU=
#     </ds:SignatureValue>
#     <ds:KeyInfo>
#       <ds:X509Data>
#         <ds:X509Certificate>
#           MIIDgzCCAmugAwIBAg...AgADAA==
#         </ds:X509Certificate>
#       </ds:X509Data>
#     </ds:KeyInfo>
#   </ds:Signature>
# </saml2p:Response>