Pascal (Lazarus/Delphi)

Verify XML Digital Signature with an RSA Key

See more XML Digital Signatures Examples

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.

Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.Http,
  Chilkat.StringBuilder,
  Chilkat.XmlDSig;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  url: string;
  http: THttp;
  sbXml: TStringBuilder;
  dsig: TXmlDSig;
  i: Integer;
  bVerifyReferenceDigests: Boolean;
  bVerified: Boolean;

begin
  success := False;

  //  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..

  url := 'https://www.chilkatsoft.com/exampleData/signedSample1.xml';
  http := THttp.Create;
  sbXml := TStringBuilder.Create;
  success := http.QuickGetSb(url,sbXml);
  if (success <> True) then
    begin
      WriteLn(http.LastErrorText);
      Exit;
    end;

  dsig := TXmlDSig.Create;

  //  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.
  success := dsig.LoadSignatureSb(sbXml);
  if (success <> True) then
    begin
      WriteLn(dsig.LastErrorText);
      Exit;
    end;

  //  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;
  while i < dsig.NumSignatures do
    begin
      //  Select the Nth signature by setting the Selector property.
      dsig.Selector := i;

      //  The bVerifyReferenceDigests argument determines if we want
      //  to also verify each reference digest.  If set to False,
      //  then only the SignedInfo part of the Signature is verified.
      bVerifyReferenceDigests := True;
      bVerified := dsig.VerifySignature(bVerifyReferenceDigests);
      WriteLn('Signature ' + i + 1 + ' verified = ' + bVerified);

      i := i + 1;
    end;



  http.Free;
  sbXml.Free;
  dsig.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.