(Visual Basic 6.0) Verify XML Signature having KeyInfo / X509Data / X509Certificate

This example demonstrates how to verify an XML Digital Signature where the KeyInfo element contains an X509Data element, which in turn contains an X509Certificate element which contains the base64-encoded certificate.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

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

' The SOAP XML with digital signature verified in this example is available at 
' https://www.chilkatsoft.com/exampleData/sigWithX509Certificate.xml

Dim signedSoapXmlUrl As String
signedSoapXmlUrl = "https://www.chilkatsoft.com/exampleData/sigWithX509Certificate.xml"

' First, let's get the signed SOAP XML..
Dim http As New ChilkatHttp
Dim sbXml As New ChilkatStringBuilder
Dim success As Long
success = http.QuickGetSb(signedSoapXmlUrl,sbXml)
If (success <> 1) Then
    Debug.Print http.LastErrorText
    Exit Sub
End If

' The signed XML downloaded from the above URL contains the following.
' Note: Everything we need to verify the signature is already available within the signed XML.
' The KeyInfo part of the Signature contains the X.509 certificate in base64 format,
' and the public key used to verify the signature is contained within the X.509.
' Chilkat automatically fetches and uses the public key from the base64 certificate.
' 

' <?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#rsa-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/2000/09/xmldsig#sha1"/><ds:DigestValue>PIiVPpuMc1jGpWaL8ftzTOcc4gc=</ds:DigestValue></ds:Reference></ds:SignedInfo><ds:SignatureValue>dlSGYRtxv8DiGQ9THPEdPTlbwjkidCUEutVWkqhnjzKOxjl6EZPp6ibf7ogrn1QJAabo7eb/d2UjD8LXzQYB+q9OmN29dsDcg4i9hzpttjU9xt8Sc3IgdaQ+6NXStWd1AKrjNTCY52sOpIWh45uff/yjf9ynsbCo/UR8+hk6ZDCrM78YEyMj52miXzVQtSZ7f+bvWtz8iPppXXC+/zwGPAI9EPC+9uRHRRh4vzGwid+clMmh9FF/0Oe4n0G5dBZvwLPncwOMg0UxLVs63ZRdTCSku4oKReQieqNr7+hzBAKaS8NRpxMtx2XC5aR0wYMkYT9API/vYubeU0L3r4lplw==</ds:SignatureValue><ds:KeyInfo><ds:X509Data><ds:X509Certificate>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</ds:X509Certificate></ds:X509Data></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>

' To verify this signature, we simply load and verify:
Dim verifier As New ChilkatXmlDSig
success = verifier.LoadSignatureSb(sbXml)
If (success <> 1) Then
    Debug.Print verifier.LastErrorText
    Exit Sub
End If

Dim bVerified As Long
bVerified = verifier.VerifySignature(1)
If (bVerified <> 1) Then
    Debug.Print verifier.LastErrorText
    Exit Sub
End If

Debug.Print "Signature verified!"