#ifndef MOBIUS_CRYPT_HMAC_H
#define MOBIUS_CRYPT_HMAC_H

// =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
// Mobius Forensic Toolkit
// Copyright (C) 2008,2009,2010,2011,2012,2013,2014,2015,2016,2017,2018,2019 Eduardo Aguiar
//
// This program is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2, or (at your option) any later
// version.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
// Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
// =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
#include <mobius/bytearray.h>
#include <mobius/crypt/hash.h>
#include <string>

namespace mobius
{
namespace crypt
{
// =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
//! \brief HMAC message authentication implementation
//! \author Eduardo Aguiar
//! \see RFC 2104
// =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
class hmac
{
public:
  explicit hmac (const bytearray&, const std::string& = "md5");
  bytearray get_digest ();
  void reset ();

  // =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
  //! \brief update HMAC object
  //! \param data input data
  // =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
  void
  update (const bytearray& data)
  {
    h_inner_.update (data);
  }

  // =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
  //! \brief get digest as hex string
  //! \return hex digest
  // =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
  std::string
  get_hex_digest ()
  {
    return get_digest ().to_hexstring ();
  }

private:
  //! \brief inner hash: H (K ^ ipad || text)
  mobius::crypt::hash h_inner_;

  //! \brief outer hash: H (K ^ opad || h_inner_.get_digest ())
  mobius::crypt::hash h_outer_;
  
  //! \brief inner hash initial value
  mobius::crypt::hash h_inner_0_;

  //! \brief outer hash initial value
  mobius::crypt::hash h_outer_0_;
};

} // namespace crypt
} // namespace mobius

#endif
