Lazarus Pascal Requires Chilkat v11.0.0+

Demonstrate RSA Encrypt/Decrypt using BinData

See more RSA Examples

Demonstrates how to RSA encrypt and decrypt data contained in a Chilkat BinData object. 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.BinData,
  Chilkat.PrivateKey,
  Chilkat.Rsa,
  Chilkat.PublicKey;

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

procedure RunDemo;
var
  success: Boolean;
  pubKey: TPublicKey;
  rsa: TRsa;
  bd: TBinData;
  i: Integer;
  privKey: TPrivateKey;
  password: string;

begin
  success := False;

  //  The RSA public key is used for encryption, and the private key for decryption.

  //  The public key's role is to make encryption accessible to anyone while ensuring that
  //  only the private key holder can decrypt the messages.
  //  The public key is designed to be widely distributed so anyone can use it to encrypt messages
  //  intended for the owner of the private key.

  //  Load our 2048-bit RSA public key.
  pubKey := TPublicKey.Create;
  //  In all Chilkat methods expecting a path, you pass either absolute or relative paths.
  success := pubKey.LoadFromFile('rsaKeys/myTestRsaPublic.pem');
  if (success = False) then
    begin
      WriteLn(pubKey.LastErrorText);
      Exit;
    end;

  rsa := TRsa.Create;

  //  Tell RSA to use the public key.
  rsa.UsePublicKey(pubKey);

  //  RSA encryption is for small amounts of data, on the order of 200 bytes or less.
  //  The maximum number of bytes that can be RSA encrypted depends
  //  on the RSA key size and padding scheme (OAEP padding vs PKCS#1 v1.5 padding).
  //  For specific limits, see: RSA Encryption Maximum Number of Bytes

  //  Create some binary data to encrypt.
  bd := TBinData.Create;
  i := 0;
  for i := 0 to 49 do
    begin
      bd.AppendByte(i);
    end;

  //  Show the bytes to be encrypted in hex format:
  WriteLn('To be encrypted: ' + bd.GetEncoded('hex'));

  //  To be encrypted: 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F202122232425262728292A2B2C2D2E2F3031

  //  RSA encrypt the contents of the bd, replacing the contents with the RSA encrypted data.
  rsa.EncryptBd(bd,False);

  //  Now it is encrypted.
  WriteLn('Encrypted size = ' + bd.NumBytes);
  WriteLn(bd.GetEncoded('hex'));

  //  Encrypted size = 256
  //  749ED9D0A8767C06C09AD9697F654F86B145F966722F9714902C4175BDBD02E68984ECF111D4D461
  //  EDB4A8E677D399D19CCA60F35C6DE9972F4262880FE9D77DB75915393E8E7DB80AAB5E383013FAEB
  //  60C77D1E6FECC9A7C8426976416C6218FE7DA998EE063CE709E79C240F8625F4A56A0A33AFD63F7A
  //  BA26F2A692B42E878C53B78602C725FE63FF961A46A2B9D436E5E3D9D64AE3F1D1F5AD5F5B47FCD69
  //  447306B77F2FD6D766CCAA1A110A3371586B43DF0D7FFE2220D1B305CF9371AC342F849FB0C90CD99E
  //  C176928D877FE1C0DE1A7CB6EB824FEC7E1DCF90EF2C6BA9F1DFD3EBFBE89C51AF074DC6AE02E544A78
  //  5018C36D3D48B2EF5202AF61AC

  //  ------------------------------------------------------------------------------------------------------------------------
  //  Let's decrypt, which requires the matching private key...

  //  Load the matching 2048-bit RSA private key.
  privKey := TPrivateKey.Create;
  password := 'secret';
  success := privKey.LoadAnyFormatFile('rsaKeys/myTestRsaPrivate.pem',password);
  if (success = False) then
    begin
      WriteLn(privKey.LastErrorText);
      Exit;
    end;

  //  Tell the RSA object to use the private key.
  rsa.UsePrivateKey(privKey);

  //  Decrypt
  success := rsa.DecryptBd(bd,True);
  if (success = False) then
    begin
      WriteLn(rsa.LastErrorText);
      Exit;
    end;

  //  Examine the contents of bd to see if it now contains the unencrypted original data.
  WriteLn('Decrypted: ' + bd.GetEncoded('hex'));

  //  Decrypted: 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F202122232425262728292A2B2C2D2E2F3031


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