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 <commoncpp/config.h>

#include <ccrtp/rtppkt.h>


#define REPLAY_WINDOW_SIZE 64

const int SrtpAuthenticationNull     =  0;
const int SrtpAuthenticationSha1Hmac =  1;
const int SrtpAuthenticationSkeinHmac = 2;

const int SrtpEncryptionNull  = 0;
const int SrtpEncryptionAESCM = 1;
const int SrtpEncryptionAESF8 = 2;
const int SrtpEncryptionTWOCM = 3;
const int SrtpEncryptionTWOF8 = 4;

#ifndef CRYPTOCONTEXTCTRL_H

#include <stdint.h>

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

class SrtpSymCrypto;

NAMESPACE_COMMONCPP

    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 ssrcCtx;}

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

    private:

        uint32 ssrcCtx;
        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;

        int32 ealg;
        int32 aalg;
        int32 ekeyl;
        int32 akeyl;
        int32 skeyl;
        int32 tagLength;
        bool  seqNumSet;

        void*   macCtx;

#ifdef SRTP_SUPPORT
        SrtpSymCrypto* cipher;
        SrtpSymCrypto* f8Cipher;
#else
        void* cipher;
        void* f8Cipher;
#endif

    };

END_NAMESPACE

#endif

#endif

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