(DataFlex) Verify an XML Signature with Multiple References

Demonstrates how to verify an XML digital signature that contains multiple references.

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

Use ChilkatAx-9.5.0-win32.pkg

Procedure Test
    Handle hoHttp
    Variant vSbXml
    Handle hoSbXml
    Boolean iSuccess
    Handle hoVerifier
    Boolean iVerifyReferenceDigests
    Boolean iVerified
    Boolean iSignedInfoVerified
    Integer iNumRefs
    Integer i
    Boolean iRefDigestVerified
    String sTemp1

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

    // An example of an enveloping XML signature with mulitple references is available at
    // https://www.chilkatsoft.com/exampleData/envelopedMultipleRefs.xml

    // This example will show how to verify the signature and all references, and also how
    // to verify each reference individually.  This is useful to distinguish which part
    // of the XML signature validation failed.  It could be that one or more of the references
    // failed because of a hash computation mismatch.  Or it could be that the signature over
    // the SignedInfo failed.  

    // First, let's grab the sample XML signature.
    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 "https://www.chilkatsoft.com/exampleData/envelopedMultipleRefs.xml" vSbXml To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoHttp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Load the XML containing the signature to be verified.
    Get Create (RefClass(cComChilkatXmlDSig)) To hoVerifier
    If (Not(IsComObjectCreated(hoVerifier))) Begin
        Send CreateComObject of hoVerifier
    End
    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

    Move True To iVerifyReferenceDigests

    // The quick way to validate all references and the signature over the SignedInfo
    // is to call VerifySignature with verifyReferenceDigests equal to True.
    Get ComVerifySignature Of hoVerifier iVerifyReferenceDigests To iVerified
    Showln "Signature and all reference digests verified = " iVerified

    // Let's pretend the call to VerifySignature returned False.  Something did not validate.
    // Was it one or more of the References that did not hash to the correct value?
    // Or was it the signature over the SignedInfo that failed?
    // We can check just the signature over the SignedInfo by passing False to VerifySignature.
    // This allows us to skip the hashing and checking each Reference.  
    Move False To iVerifyReferenceDigests
    Get ComVerifySignature Of hoVerifier iVerifyReferenceDigests To iSignedInfoVerified
    Showln "Neglecting the reference hashes, the SignedInfo validation result = " iSignedInfoVerified

    // We can also verify each reference digest separately
    Get ComNumReferences Of hoVerifier To iNumRefs
    Move 0 To i
    While (i < iNumRefs)
        Get ComVerifyReferenceDigest Of hoVerifier i To iRefDigestVerified
        Showln "Reference " i " digest verified = " iRefDigestVerified
        Move (i + 1) To i
    Loop

    // For this sample XML signature with 3 References, we get the following output:

    // Signature and all reference digests verified = True
    // Neglecting the reference hashes, the SignedInfo validation result = True
    // Reference 0 digest verified = True
    // Reference 1 digest verified = True
    // Reference 2 digest verified = Tru


End_Procedure