Lazarus Pascal

Extract SignatureValue from Signed XML

See more XML Digital Signatures Examples

Demonstrates how to extract the signature value from signed XML. 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.Xml,
  Chilkat.StringBuilder;

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

procedure RunDemo;
var
  success: Boolean;
  filePath: string;
  sb: TStringBuilder;
  base64Sig: string;
  xml: TXml;
  xSigVal: TXml;

begin
  success := False;

  //  This example will work with the following signed XML, which as been reformatted for readability.

  //  <?xml version="1.0" encoding="utf-8"?>
  //  <SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
  //      <SOAP-ENV:Header>
  //          <wsse:Security xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd" SOAP-ENV:mustUnderstand="1">
  //              <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#">
  //                          <InclusiveNamespaces xmlns="http://www.w3.org/2001/10/xml-exc-c14n#" PrefixList="wsse SOAP-ENV"/>
  //                      </ds:CanonicalizationMethod>
  //                      <ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha256"/>
  //                      <ds:Reference URI="#Body">
  //                          <ds:Transforms>
  //                              <ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
  //                          </ds:Transforms>
  //                          <ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/>
  //                          <ds:DigestValue>OwgHPZNfDkXnZsjpfzXqAcT3RV3HzmTsEy2bP44FJ0M=</ds:DigestValue>
  //                      </ds:Reference>
  //                  </ds:SignedInfo>
  //                  <ds:SignatureValue>C+7FWngU....DJFBcdg==</ds:SignatureValue>
  //                  <ds:KeyInfo>
  //                      <ds:KeyValue>
  //                          <ds:RSAKeyValue>
  //                              <ds:Modulus>sXeRhM55P13.....NAcibRw==</ds:Modulus>
  //                              <ds:Exponent>AQAB</ds:Exponent>
  //                          </ds:RSAKeyValue>
  //                      </ds:KeyValue>
  //                  </ds:KeyInfo>
  //              </ds:Signature>
  //          </wsse:Security>
  //      </SOAP-ENV:Header>
  //      <SOAP-ENV:Body xmlns:SOAP-SEC="http://schemas.xmlsoap.org/soap/security/2000-12" SOAP-SEC:id="Body">
  //          <z:FooBar xmlns:z="http://example.com"/>
  //      </SOAP-ENV:Body>
  //  </SOAP-ENV:Envelope>

  //  -----------------------------------------------------------------------------------------
  //  There are a number of ways we can get the contents of the  <ds:SignatureValue>...</ds:SignatureValue>

  filePath := 'qa_data/xml_dsig_testing/sample_to_show_how_to_extract_sig.xml';

  //  If you know there will only be a single SignatureValue in the XML, you don't need to parse XML.
  //  Just do quick and simple string search..
  //  For example:
  sb := TStringBuilder.Create;
  success := sb.LoadFile(filePath,'utf-8');
  if (success = False) then
    begin
      WriteLn('Failed to load file.');
      Exit;
    end;

  base64Sig := sb.GetBetween('SignatureValue>','</');
  WriteLn('base64Sig = ' + base64Sig);

  //  -----------------------------------------------------------------------------------------
  //  If the XML might contain multiple signatures, but the signatures will always be located in the 
  //  same place, then you can (beforehand) copy a sample signed XML into Chilkat's online tool
  //  at Generate Parsing Code from XML
  //  to get the path to the SignatureValue.  For example, the line of code generated for the SignatureValue
  //  for the above XML is:
  //  string ds_SignatureValue = xml.GetChildContent("SOAP-ENV:Header|wsse:Security|ds:Signature|ds:SignatureValue");

  //  So you can simply use that path..
  xml := TXml.Create;
  success := xml.LoadXmlFile(filePath);
  //  Assume success..

  base64Sig := xml.GetChildContent('SOAP-ENV:Header|wsse:Security|ds:Signature|ds:SignatureValue');
  WriteLn('base64Sig = ' + base64Sig);

  //  -----------------------------------------------------------------------------------------
  //  Or perhaps you don't know where the signature is located in the XML.
  //  You can search for the tag..
  xSigVal := xml.SearchForTag(xml,'*:SignatureValue');
  if (xml.LastMethodSuccess = True) then
    begin
      WriteLn('base64Sig = ' + xSigVal.Content);
      xSigVal.Free;
    end
  else
    begin
      WriteLn('No SignatureValue found.');
    end;


  sb.Free;
  xml.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.