Pascal (Lazarus/Delphi)

RSA Sign Binary Data and Verify (Recover the Original Data)

See more RSA Examples

Demonstrates how to RSA sign binary data and then verify/recover the original data.

Note: This example uses methods introduced in Chilkat v9.5.0.77.

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.BinData,
  Chilkat.PrivateKey,
  Chilkat.Rsa,
  Chilkat.PublicKey;

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

procedure RunDemo;
var
  success: Boolean;
  privKey: TPrivateKey;
  rsa: TRsa;
  originalData: string;
  bd: TBinData;
  pubKey: TPublicKey;
  rsa2: TRsa;
  bVerified: Boolean;

begin
  success := False;

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

  //  Load an RSA private key for signing.
  privKey := TPrivateKey.Create;
  success := privKey.LoadEncryptedPemFile('qa_data/pem/rsa_passwd.pem','passwd');
  if (success = False) then
    begin
      WriteLn(privKey.LastErrorText);
      Exit;
    end;

  rsa := TRsa.Create;
  rsa.UsePrivateKey(privKey);

  //  We have some binary data (in hex) to sign
  originalData := '0102030405060708090A';
  bd := TBinData.Create;
  bd.AppendEncoded(originalData,'hex');

  //  If successful, the contents of bd are replaced with the RSA signature.
  success := rsa.SignRawBd(bd);
  if (success = False) then
    begin
      WriteLn(rsa.LastErrorText);
      Exit;
    end;

  //  Show the RSA signature in base64
  WriteLn(bd.GetEncoded('base64'));

  //  ------------------------------------------
  //  Get the public key from the private key
  pubKey := TPublicKey.Create;
  privKey.ToPublicKey(pubKey);

  //  Verify the signature and extract the original data.
  rsa2 := TRsa.Create;
  rsa2.UsePublicKey(pubKey);

  bVerified := rsa2.VerifyRawBd(bd);
  WriteLn('signature verified: ' + bVerified);

  //  Show the original data:
  WriteLn('original data: ' + bd.GetEncoded('hex'));


  privKey.Free;
  rsa.Free;
  bd.Free;
  pubKey.Free;
  rsa2.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.