(DataFlex) Verify XML Signature having KeyInfo / X509Data / X509SKI

This example demonstrates how to verify an XML Digital Signature where the KeyInfo element contains an X509Data element,
which in turn contains an X509SKI element which contains only the signing certificate's Subject Key Identifier (SKI).

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

Use ChilkatAx-win32.pkg

Procedure Test
    String sSignedSoapXmlUrl
    Handle hoHttp
    Variant vSbXml
    Handle hoSbXml
    Boolean iSuccess
    Variant vSbCertPem
    Handle hoSbCertPem
    Variant vCertVault
    Handle hoCertVault
    Handle hoVerifier
    Boolean iBVerified
    String sTemp1

    // 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/sigWithX509SKI.xml

    Move "https://www.chilkatsoft.com/exampleData/sigWithX509SKI.xml" To sSignedSoapXmlUrl

    // First, let's get the signed SOAP XML..
    Get Create (RefClass(cComChilkatHttp)) To hoHttp
    If (Not(IsComObjectCreated(hoHttp))) Begin
        Send CreateComObject of hoHttp
    End
    Get Create (RefClass(cComChilkatStringBuilder)) To hoSbXml
    If (Not(IsComObjectCreated(hoSbXml))) Begin
        Send CreateComObject of hoSbXml
    End
    Get pvComObject of hoSbXml to vSbXml
    Get ComQuickGetSb Of hoHttp sSignedSoapXmlUrl vSbXml To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoHttp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // The signed XML downloaded from the above URL 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"><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>Rlta8LplnFH0q8L+UeVmh4Smdn6oVETi4RoUmpT/KQX3RNAIOdCVE3b7gjmx5+3vp3DhjphOsZvW6dXzkI46xt9pD5otp3b/ZppGqKzltggo9gyQtPvJ8ltJZqVKYOGo5uElRFF/xm/zcx5Y3E14t+LYVSlv2lbem/zZ5zQ7ai8DmGD33id7nGu+MXVwb3kGkJFYoB/GOXtwsep+bcilMglTp8/7SBfBaVFKxWVBp4N2NW7bGlyDct8FaCk9hXQDNm/kqne9GU87tgh8/rbsFCYgyqIRMIvMPvhRWr2EKdEKyLtlZ8w0KYJYpgsf4T7SDghemzXkJoJPrfUQmHudIw==</ds:SignatureValue><ds:KeyInfo><ds:X509Data><ds:X509SKI>bDMtm8bAimMlGLU2M/82W8+y3tM=</ds:X509SKI></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>

    // Note: We don't have everything we need to verify the signature.
    // The KeyInfo part of the Signature contains only the signing cert's Subject Key Identifier.  
    // We must obtain the certificate locally using this information.  
    // 
    // On a Windows system, if the matching certificate is already installed in the registry-based
    // certificate stores, then your application does not need to do anything.  Chilkat will automatically
    // locate and use the matching certificate installed on the Windows system.
    // 
    // This example will assume we're not on a Windows system, or that the matching certificate
    // is not already installed on the system.
    // 

    // One strategy for providing certificates to the application doing the XML signature verification 
    // is to load all possible certificates into an in-memory XmlCertVault beforehand, and then call
    // UseCertVault to allow for Chilkat to automatically find the matching cert from the pre-loaded certificates.
    // We'll do that here with the one certificate that we already know is the matching certificate.

    Get Create (RefClass(cComChilkatStringBuilder)) To hoSbCertPem
    If (Not(IsComObjectCreated(hoSbCertPem))) Begin
        Send CreateComObject of hoSbCertPem
    End
    Get pvComObject of hoSbCertPem to vSbCertPem
    Get ComQuickGetSb Of hoHttp "https://chilkatdownload.com/example_data/testcertificate.pem" vSbCertPem To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoHttp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Create a cert vault and add the certificates.
    // In this example, we're only adding a single certificate.  An application
    // could load many certificates into the cert vault..
    Get Create (RefClass(cComChilkatXmlCertVault)) To hoCertVault
    If (Not(IsComObjectCreated(hoCertVault))) Begin
        Send CreateComObject of hoCertVault
    End
    Get ComGetAsString Of hoSbCertPem To sTemp1
    Get ComAddCertString Of hoCertVault sTemp1 To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoCertVault To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get Create (RefClass(cComChilkatXmlDSig)) To hoVerifier
    If (Not(IsComObjectCreated(hoVerifier))) Begin
        Send CreateComObject of hoVerifier
    End

    // Tell the verifier to use the certVault as a source for locating
    // matching certificates.
    Get pvComObject of hoCertVault to vCertVault
    Get ComUseCertVault Of hoVerifier vCertVault To iSuccess

    Get pvComObject of hoSbXml to vSbXml
    Get ComLoadSignatureSb Of hoVerifier vSbXml To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoVerifier To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComVerifySignature Of hoVerifier True To iBVerified
    If (iBVerified <> True) Begin
        Get ComLastErrorText Of hoVerifier To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln "Signature verified!"


End_Procedure