Lazarus Pascal

Verify HMAC XML Digital Signature

See more XML Digital Signatures Examples

Demonstrates how to validate an XML digital signature signed with an HMAC key. Lazarus Pascal

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;
  verifier: TXmlDSig;
  bVerified: Boolean;

begin
  success := False;

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

  //  The XML containing the Signature to be verified contains the following:

  //  <?xml version="1.0" encoding="UTF-8" standalone="no"?>
  //  <collection Id="root">
  //  	<album>
  //  		<title>Questions, unanswered</title>
  //  		<artist>Steve and the flubberblubs</artist>
  //  		<year>1989</year>
  //  		<t:tracks xmlns:t="http://test.xades4j/tracks">
  //  			<t:song length="4:05" tracknumber="1">
  //  				<t:title>What do you know?</t:title>
  //  				<t:artist>Steve and the flubberblubs</t:artist>
  //  				<t:lastplayed>2006-10-17-08:31</t:lastplayed>
  //  			</t:song>
  //  			<t:song length="3:45" tracknumber="2">
  //  				<t:title>Who do you know?</t:title>
  //  				<t:artist>Steve and the flubberblubs</t:artist>
  //  				<t:lastplayed>2006-10-17-08:35</t:lastplayed>
  //  			</t:song>
  //  			<t:song length="5:14" tracknumber="3">
  //  				<t:title>When do you know?</t:title>
  //  				<t:artist>Steve and the flubberblubs</t:artist>
  //  				<t:lastplayed>2006-10-17-08:39</t:lastplayed>
  //  			</t:song>
  //  			<t:song length="4:19" tracknumber="4">
  //  				<t:title>Do you know?</t:title>
  //  				<t:artist>Steve and the flubberblubs</t:artist>
  //  				<t:lastplayed>2006-10-17-08:44</t:lastplayed>
  //  			</t:song>
  //  		</t:tracks>
  //  	</album>
  //  <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#"/><ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#hmac-sha256"/><ds:Reference URI="#root"><ds:Transforms><ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/></ds:Transforms><ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/><ds:DigestValue>rD/g8soqKz8EiPUBhEWfcQacS0ta4ULHX3dKMEH6ZoQ=</ds:DigestValue></ds:Reference></ds:SignedInfo><ds:SignatureValue>R8dXP95VRYJBfL6d0Peogybdk27+R+JIfX8jnVu0NOI=</ds:SignatureValue></ds:Signature></collection>

  //  The above XML is available at https://www.chilkatsoft.com/exampleData/hmacSigned.xml
  //  First fetch the XML..

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

  verifier := TXmlDSig.Create;

  //  Load the XML containing the signature to be verified.
  success := verifier.LoadSignatureSb(sbXml);
  if (success <> True) then
    begin
      WriteLn(verifier.LastErrorText);
      Exit;
    end;

  //  Provide the HMAC key
  //  The HMAC key for this signature is the us-ascii bytes of the string "secret",
  //  It can be set in any of the following ways (and also more ways not shown here..)
  verifier.SetHmacKey('secret','ascii');
  //  or
  verifier.SetHmacKey('c2VjcmV0','base64');
  //  or
  verifier.SetHmacKey('736563726574','hex');

  //  Verify the signature
  bVerified := verifier.VerifySignature(True);
  WriteLn('Signature verified = ' + bVerified);


  http.Free;
  sbXml.Free;
  verifier.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.