KeyAgreementResponder.hpp

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/*
    Copyright (c) 2009-2010 Christopher A. Taylor.  All rights reserved.

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#ifndef CAT_KEY_AGREEMENT_RESPONDER_HPP
#define CAT_KEY_AGREEMENT_RESPONDER_HPP

#include <cat/crypt/tunnel/KeyAgreement.hpp>
#include <cat/crypt/tunnel/AuthenticatedEncryption.hpp>
#include <cat/threads/Atomic.hpp>

#if defined(CAT_NO_ATOMIC_ADD) || defined(CAT_NO_ATOMIC_SET)
# include <cat/threads/Mutex.hpp>
# define CAT_NO_ATOMIC_RESPONDER
#endif

namespace cat {


class KeyAgreementResponder : public KeyAgreementCommon
{
    Leg *b; // Responder's private key (kept secret)
    Leg *B; // Responder's public key (pre-shared with initiator)
    Leg *B_neutral; // Endian-neutral B
    Leg *G_MultPrecomp; // 8-bit table for multiplication
    Leg *y[2]; // Responder's ephemeral private key (kept secret)
    Leg *Y_neutral[2]; // Responder's ephemeral public key (shared online with initiator)

#if defined(CAT_NO_ATOMIC_RESPONDER)
    Mutex m_thread_id_mutex;
#endif // CAT_NO_ATOMIC_RESPONDER

    volatile u32 ChallengeCount;
    volatile u32 ActiveY;

    void Rekey(BigTwistedEdwards *math, FortunaOutput *csprng);
    bool AllocateMemory();
    void FreeMemory();

public:
    KeyAgreementResponder();
    ~KeyAgreementResponder();

    bool Initialize(BigTwistedEdwards *math, FortunaOutput *csprng,
                    const u8 *responder_public_key, int public_bytes,
                    const u8 *responder_private_key, int private_bytes);

public:
    bool ProcessChallenge(BigTwistedEdwards *math, FortunaOutput *csprng,
                          const u8 *initiator_challenge, int challenge_bytes,
                          u8 *responder_answer, int answer_bytes, Skein *key_hash);

    inline bool KeyEncryption(Skein *key_hash, AuthenticatedEncryption *auth_enc, const char *key_name)
    {
        return auth_enc->SetKey(KeyBytes, key_hash, false, key_name);
    }

public:
    bool Sign(BigTwistedEdwards *math, FortunaOutput *csprng,
              const u8 *message, int message_bytes,
              u8 *signature, int signature_bytes);
};


} // namespace cat

#endif // CAT_KEY_AGREEMENT_RESPONDER_HPP