Lazarus Pascal

AES OFB Output Feedback Mode Encryption

See more Encryption Examples

Demonstrates how to encrypt using AES OFB (Output Feedback) mode. 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.Crypt2;

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

procedure RunDemo;
var
  crypt: TCrypt2;
  ivHex: string;
  keyHex: string;
  encStr: string;
  decrypt: TCrypt2;
  decStr: string;

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

  crypt := TCrypt2.Create;

  crypt.CryptAlgorithm := 'aes';
  //  Set the cipher mode to Output Feedback
  crypt.CipherMode := 'ofb';
  crypt.KeyLength := 256;

  //  EncodingMode specifies the encoding of the output for
  //  encryption, and the input for decryption.
  //  It may be "hex", "url", "base64", "quoted-printable", or many other choices.
  crypt.EncodingMode := 'hex';

  ivHex := '000102030405060708090A0B0C0D0E0F';
  crypt.SetEncodedIV(ivHex,'hex');

  //  The secret key must equal the size of the key.  For
  //  256-bit encryption, the binary secret key is 32 bytes.
  keyHex := '603deb1015ca71be2b73aef0857d77811f352c073b6108d72d9810a30914dff4';
  crypt.SetEncodedKey(keyHex,'hex');

  //  Encrypt a string...
  encStr := crypt.EncryptStringENC('Popular opinions, on subjects not palpable to sense, are often true, but seldom or never the whole truth. -- John Stuart Mill');
  WriteLn(encStr);

  decrypt := TCrypt2.Create;
  decrypt.CryptAlgorithm := 'aes';
  decrypt.CipherMode := 'ofb';
  decrypt.KeyLength := 256;
  decrypt.EncodingMode := 'hex';
  decrypt.SetEncodedIV(ivHex,'hex');
  decrypt.SetEncodedKey(keyHex,'hex');

  //  Now decrypt:
  decStr := decrypt.DecryptStringENC(encStr);
  WriteLn(decStr);


  crypt.Free;
  decrypt.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.