(Classic ASP) 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.

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

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.XmlDSig")
set dsig = Server.CreateObject("Chilkat.XmlDSig")
success = dsig.LoadSignature("XML xml signature goes here...")

' A sample SAML signature is shown below..

numSignatures = dsig.NumSignatures
i = 0
Do While i < numSignatures
    dsig.Selector = i

    bVerifyRefDigests = 0
    bSignatureVerified = dsig.VerifySignature(bVerifyRefDigests)
    If (bSignatureVerified = 1) Then
        Response.Write "<pre>" & Server.HTMLEncode( "Signature " & i + 1 & " verified") & "</pre>"
    Else
        Response.Write "<pre>" & Server.HTMLEncode( "Signature " & i + 1 & " invalid") & "</pre>"
    End If

    ' Check each of the reference digests separately..
    numRefDigests = dsig.NumReferences
    j = 0
    Do While j < numRefDigests
        bDigestVerified = dsig.VerifyReferenceDigest(j)
        Response.Write "<pre>" & Server.HTMLEncode( "reference digest " & j + 1 & " verified = " & bDigestVerified) & "</pre>"
        If (bDigestVerified = 0) Then
            Response.Write "<pre>" & Server.HTMLEncode( "    reference digest fail reason: " & dsig.RefFailReason) & "</pre>"
        End If

        j = j + 1
    Loop

    i = i + 1
Loop

' --------------------------------------
' 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>

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