PowerBuilder

Verify XML Signature with External URL References

See more XML Digital Signatures Examples

Demonstrates how to verify an XML digital signature that includes references to URLs where the data to be digested is on a web server. PowerBuilder

integer li_rc
integer li_Success
oleobject loo_Verifier
oleobject loo_Http
oleobject loo_SbSignedXml
oleobject loo_SbRefUri
oleobject loo_Bd
integer li_NumRefs
integer i
integer li_BVerified

li_Success = 0

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

// The signed XML we wish to verify contains external references such as this:

//     <ds:Reference Id="xmldsig-e7ae7ce2-9133-4d56-bd97-0a6aef738cc2-ref0" URI="https://www.chilkatsoft.com/images/starfish.jpg">
//       <ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/>
//       <ds:DigestValue>AOU810yJV5Np/DnO29qpObqiTSTTCDvxGsX5ayiTYXI=</ds:DigestValue>
//     </ds:Reference>
//     <ds:Reference Id="xmldsig-e7ae7ce2-9133-4d56-bd97-0a6aef738cc2-ref1" URI="https://www.chilkatsoft.com/hamlet.xml">
//       <ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/>
//       <ds:DigestValue>4sRRyWOzC7EOic4fQ9+Op1pa10DbgoBGjBvkq09LZmE=</ds:DigestValue>
//     </ds:Reference>

loo_Verifier = create oleobject
li_rc = loo_Verifier.ConnectToNewObject("Chilkat.XmlDSig")
if li_rc < 0 then
    destroy loo_Verifier
    MessageBox("Error","Connecting to COM object failed")
    return
end if
loo_Http = create oleobject
li_rc = loo_Http.ConnectToNewObject("Chilkat.Http")

// First load the signed XML
loo_SbSignedXml = create oleobject
li_rc = loo_SbSignedXml.ConnectToNewObject("Chilkat.StringBuilder")

li_Success = loo_SbSignedXml.LoadFile("qa_data/xml_dsig_verify/signedWithExternalUrlRefs.xml","utf-8")
if li_Success = 0 then
    Write-Debug "Failed to load signed XML."
    destroy loo_Verifier
    destroy loo_Http
    destroy loo_SbSignedXml
    return
end if

li_Success = loo_Verifier.LoadSignatureSb(loo_SbSignedXml)
if li_Success = 0 then
    Write-Debug loo_Verifier.LastErrorText
    destroy loo_Verifier
    destroy loo_Http
    destroy loo_SbSignedXml
    return
end if

// Iterate over each reference.  If it is an external URL reference, download the data and provide it to the verifier.
loo_SbRefUri = create oleobject
li_rc = loo_SbRefUri.ConnectToNewObject("Chilkat.StringBuilder")

loo_Bd = create oleobject
li_rc = loo_Bd.ConnectToNewObject("Chilkat.BinData")

li_NumRefs = loo_Verifier.NumReferences
i = 0
do while i < li_NumRefs
    if loo_Verifier.IsReferenceExternal(i) = 1 then
        loo_SbRefUri.Clear()
        loo_SbRefUri.Append(loo_Verifier.ReferenceUri(i))
        if loo_SbRefUri.StartsWith("https://",0) = 1 then
            Write-Debug "External URL Reference: " + loo_SbRefUri.GetAsString()

            // Download the data at the URL and provide to the verifier.
            li_Success = loo_Http.DownloadBd(loo_SbRefUri.GetAsString(),loo_Bd)
            if li_Success = 0 then
                Write-Debug loo_Http.LastErrorText
                destroy loo_Verifier
                destroy loo_Http
                destroy loo_SbSignedXml
                destroy loo_SbRefUri
                destroy loo_Bd
                return
            end if

            li_Success = loo_Verifier.SetRefDataBd(i,loo_Bd)
            if li_Success = 0 then
                Write-Debug loo_Verifier.LastErrorText
                destroy loo_Verifier
                destroy loo_Http
                destroy loo_SbSignedXml
                destroy loo_SbRefUri
                destroy loo_Bd
                return
            end if

        end if

    end if

    i = i + 1
loop

// Now that we have the external data, verify the signature..
li_BVerified = loo_Verifier.VerifySignature(1)
if li_BVerified = 0 then
    Write-Debug loo_Verifier.LastErrorText
end if

Write-Debug "Signature verified = " + string(li_BVerified)


destroy loo_Verifier
destroy loo_Http
destroy loo_SbSignedXml
destroy loo_SbRefUri
destroy loo_Bd