Pascal (Lazarus/Delphi)

RSA Hash Binary Data and Sign (and Verify)

See more RSA Examples

Demonstrates how to sign the hash of binary data. Also demonstrates how to verify the RSA signature. 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;
  bdData: TBinData;
  bdSignature: 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';
  bdData := TBinData.Create;
  bdData.AppendEncoded(originalData,'hex');

  //  Hash (SHA-256) and sign the hash:
  bdSignature := TBinData.Create;
  success := rsa.SignBd(bdData,'sha256',bdSignature);
  if (success = False) then
    begin
      WriteLn(rsa.LastErrorText);
      Exit;
    end;

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

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

  //  Verify the signature..
  rsa2 := TRsa.Create;
  rsa2.UsePublicKey(pubKey);

  bVerified := rsa2.VerifyBd(bdData,'sha256',bdSignature);
  WriteLn('signature verified: ' + bVerified);


  privKey.Free;
  rsa.Free;
  bdData.Free;
  bdSignature.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.