Lazarus Pascal

Sign a Byte Array to Create an Opaque Signature in a Byte Array

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Signs data contained in a byte array to produce an opaque signature (also in a byte array). An opaque signature is a PKCS7 signature (also known as CAdES) that embeds the signed data. Also shows how to verify the signature and extract the original data. 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.FileAccess,
  Chilkat.Cert,
  Chilkat.Crypt2;

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

procedure RunDemo;
var
  success: Boolean;
  cert: TCert;
  fac: TFileAccess;
  fileBytes: TBytes;
  crypt: TCrypt2;
  sigBytes: TBytes;
  originalData: TBytes;

begin
  success := False;

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

  cert := TCert.Create;
  success := cert.LoadPfxFile('qa_data/pfx/cert_test123.pfx','test123');
  if (success = False) then
    begin
      WriteLn(cert.LastErrorText);
      Exit;
    end;

  fac := TFileAccess.Create;

  fileBytes := fac.ReadEntireFile('qa_data/pdf/sample.pdf');
  if (fac.LastMethodSuccess <> True) then
    begin
      WriteLn(fac.LastErrorText);
      Exit;
    end;

  crypt := TCrypt2.Create;

  success := crypt.SetSigningCert(cert);

  //  We can sign any type of file.

  sigBytes := crypt.OpaqueSignBytes(fileBytes);
  if (crypt.LastMethodSuccess <> True) then
    begin
      WriteLn(crypt.LastErrorText);
      Exit;
    end;

  success := fac.WriteEntireFile('qa_output/sample.pdf.p7m',sigBytes);
  if (fac.LastMethodSuccess <> True) then
    begin
      WriteLn(fac.LastErrorText);
      Exit;
    end;

  //  We can verify the opaque signature and extract the original data like this

  originalData := crypt.OpaqueVerifyBytes(sigBytes);
  if (crypt.LastMethodSuccess <> True) then
    begin
      WriteLn(crypt.LastErrorText);
      Exit;
    end;

  success := fac.WriteEntireFile('qa_output/sample.pdf',originalData);
  if (fac.LastMethodSuccess <> True) then
    begin
      WriteLn(fac.LastErrorText);
      Exit;
    end;

  WriteLn('Signature is verified and the original data was extracted.');


  cert.Free;
  fac.Free;
  crypt.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.