CryptoContext.h

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/*
  Copyright (C) 2004-2006 the Minisip Team

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library 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
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
*/



#ifndef CRYPTOCONTEXT_H
#define CRYPTOCONTEXT_H

#include <cc++/config.h>

#include <ccrtp/rtppkt.h>

#ifdef SRTP_SUPPORT
#include <ccrtp/crypto/AesSrtp.h>
#endif

#define REPLAY_WINDOW_SIZE 64


const int SrtpAuthenticationNull     = 0;
const int SrtpAuthenticationSha1Hmac = 1;

const int SrtpEncryptionNull  = 0;
const int SrtpEncryptionAESCM = 1;
const int SrtpEncryptionAESF8 = 2;

#ifdef CCXX_NAMESPACES
namespace ost {
#endif

    class RTPPacket;

    class __EXPORT CryptoContext {
        public:
            CryptoContext( uint32 ssrc );

            CryptoContext( uint32 ssrc, int32 roc,
                           int64  keyDerivRate,
                           const  int32 ealg,
                           const  int32 aalg,
                           uint8* masterKey,
                           int32  masterKeyLength,
                           uint8* masterSalt,
                           int32  masterSaltLength,
                           int32  ekeyl,
                           int32  akeyl,
                           int32  skeyl,
                           int32  tagLength );
            ~CryptoContext();

            inline void
            setRoc(uint32 r)
            {roc = r;}

            inline uint32
            getRoc() const
            {return roc;}

            void srtpEncrypt( RTPPacket* rtp, uint64 index, uint32 ssrc );

            void srtpAuthenticate(RTPPacket* rtp, uint32 roc, uint8* tag );

            void deriveSrtpKeys(uint64 index);

            uint64 guessIndex(uint16 newSeqNumber);

            bool checkReplay(uint16 newSeqNumber);

            void update( uint16 newSeqNumber );

            inline int32
            getTagLength() const
            {return tagLength;}


            inline int32
            getMkiLength() const
            {return mkiLength;}

            inline uint32
            getSsrc() const
            {return ssrc;}

            CryptoContext* newCryptoContextForSSRC(uint32 ssrc, int roc, int64 keyDerivRate);

        private:

            uint32 ssrc;
            bool   using_mki;
            uint32 mkiLength;
            uint8* mki;

            uint32 roc;
            uint32 guessed_roc;
            uint16 s_l;
            int64  key_deriv_rate;

            /* bitmask for replay check */
            uint64 replay_window;

            uint8* master_key;
            uint32 master_key_length;
            uint32 master_key_srtp_use_nb;
            uint32 master_key_srtcp_use_nb;
            uint8* master_salt;
            uint32 master_salt_length;

            /* Session Encryption, Authentication keys, Salt */
            int32  n_e;
            uint8* k_e;
            int32  n_a;
            uint8* k_a;
            int32  n_s;
            uint8* k_s;

            uint8 ealg;
            uint8 aalg;
            uint8 ekeyl;
            uint8 akeyl;
            uint8 skeyl;
            uint8 tagLength;
            bool  seqNumSet;
            
#ifdef SRTP_SUPPORT
            AesSrtp* aesCipher;
            AesSrtp* f8AesCipher;
#else
            void* aesCipher;
            void* f8AesCipher;
#endif

    };
#ifdef  CCXX_NAMESPACES
}
#endif

#endif