How to use?
Drop component on your form, specify password in Key property, put any two cahracters to Salt property and get encrypted password from Result. You can play with it even at design-time.  
Since the acUnixCrypt component uses one-way encryption algorithm, there is no way to decrypt the keys. For authentication you can only compare two encrypted passwords.  

procedure TForm1.AuthenticationBtnClick(Sender: TObject);  
  // we'd like to take salt from two first characters of username  
  acUnixCrypt1.Salt := Copy(RealUsername, 12);  
  // asking for password  
  acUnixCrypt1.Key := InputBox('Authentication',  
                               'Enter password:''');  
  // comparing two encrypted passwords  
  if acUnixCrypt.Result <> RealCryptedPassword then  
    ShowMessage('Authentication Failed!');