(PowerBuilder) Verify XML Digital Signature with an RSA Key

This example demonstrates how to verify an XML signature, where the RSA public key is embedded in the KeyInfo part of the Signature. When this is the case, nothing external is needed to verify the signature.

This example requires Chilkat v9.5.0.69 or greater.

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

integer li_rc
string ls_Url
oleobject loo_Http
oleobject loo_SbXml
integer li_Success
oleobject loo_Dsig
integer i
integer li_BVerifyReferenceDigests
integer li_BVerified

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

// The signed XML to be verified in this example contains the following:

// <?xml version="1.0" encoding="UTF-8"?>
// <Signature xmlns="http://www.w3.org/2000/09/xmldsig#">
// <SignedInfo>
//   <CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315" />
//   <SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1" />
//   <Reference URI="#object">
//     <DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1" />
//     <DigestValue>OPnpF/ZNLDxJ/I+1F3iHhlmSwgo=</DigestValue>
//   </Reference>
// </SignedInfo>
// <SignatureValue>nihUFQg4mDhLgecvhIcKb9Gz8VRTOlw+adiZOBBXgK4JodEe5aFfCqm8WcRIT8GLLXSk8PsUP4//SsKqUBQkpotcAqQAhtz2v9kCWdoUDnAOtFZkd/CnsZ1sge0ndha40wWDV+nOWyJxkYgicvB8POYtSmldLLepPGMz+J7/Uws=</SignatureValue>
// <KeyInfo>
//   <KeyValue>
//     <RSAKeyValue><Modulus>4IlzOY3Y9fXoh3Y5f06wBbtTg94Pt6vcfcd1KQ0FLm0S36aGJtTSb6pYKfyX7PqCUQ8wgL6xUJ5GRPEsu9gyz8ZobwfZsGCsvu40CWoT9fcFBZPfXro1Vtlh/xl/yYHm+Gzqh0Bw76xtLHSfLfpVOrmZdwKmSFKMTvNXOFd0V18=</Modulus><Exponent>AQAB</Exponent></RSAKeyValue>
//   </KeyValue>
// </KeyInfo>
// <Object Id="object">some text
//   with spaces and CR-LF.</Object>
// </Signature>

// The above XML is available at https://www.chilkatsoft.com/exampleData/signedSample1.xml
// Fetch the XML and then verify it..

ls_Url = "https://www.chilkatsoft.com/exampleData/signedSample1.xml"
loo_Http = create oleobject
// Use "Chilkat_9_5_0.Http" for versions of Chilkat < 10.0.0
li_rc = loo_Http.ConnectToNewObject("Chilkat.Http")
if li_rc < 0 then
    destroy loo_Http
    MessageBox("Error","Connecting to COM object failed")
    return
end if
loo_SbXml = create oleobject
// Use "Chilkat_9_5_0.StringBuilder" for versions of Chilkat < 10.0.0
li_rc = loo_SbXml.ConnectToNewObject("Chilkat.StringBuilder")

li_Success = loo_Http.QuickGetSb(ls_Url,loo_SbXml)
if li_Success <> 1 then
    Write-Debug loo_Http.LastErrorText
    destroy loo_Http
    destroy loo_SbXml
    return
end if

loo_Dsig = create oleobject
// Use "Chilkat_9_5_0.XmlDSig" for versions of Chilkat < 10.0.0
li_rc = loo_Dsig.ConnectToNewObject("Chilkat.XmlDSig")

// First load the XML containing the signatures to be verified.
// Note that this particular Signature already contains the RSA public key that will be used
// for verification.
li_Success = loo_Dsig.LoadSignatureSb(loo_SbXml)
if li_Success <> 1 then
    Write-Debug loo_Dsig.LastErrorText
    destroy loo_Http
    destroy loo_SbXml
    destroy loo_Dsig
    return
end if

// The XML in this example contains only 1 signature.
// It's possible that an XML document can contain multiple signatures.
// Each can be verified as follows:
i = 0
do while i < loo_Dsig.NumSignatures
    // Select the Nth signature by setting the Selector property.
    loo_Dsig.Selector = i

    // The bVerifyReferenceDigests argument determines if we want
    // to also verify each reference digest.  If set to 0,
    // then only the SignedInfo part of the Signature is verified.
    li_BVerifyReferenceDigests = 1
    li_BVerified = loo_Dsig.VerifySignature(li_BVerifyReferenceDigests)
    Write-Debug "Signature " + string(i + 1) + " verified = " + string(li_BVerified)

    i = i + 1
loop


destroy loo_Http
destroy loo_SbXml
destroy loo_Dsig