i2pd/libi2pd/ECIESX25519AEADRatchetSession.h

#ifndef ECIES_X25519_AEAD_RATCHET_SESSION_H__
#define ECIES_X25519_AEAD_RATCHET_SESSION_H__

#include <string.h>
#include <inttypes.h>
#include <functional>
#include <vector>
#include "Identity.h"
#include "Crypto.h"
#include "Garlic.h"

namespace i2p
{
namespace garlic
{
    class RatchetTagSet
    {
        public:
            
            void DHInitialize (const uint8_t * rootKey, const uint8_t * k);
            void NextSessionTagRatchet ();
            const uint8_t * GetNextSessionTag ();

        private:

           uint8_t m_CK[64], m_SessTagConstant[32];   
    };       

    enum ECIESx25519BlockType
	{
		eECIESx25519BlkDateTime = 0,
		eECIESx25519BlkSessionID = 1, 
		eECIESx25519BlkTermination = 4,
		eECIESx25519BlkOptions = 5,
		eECIESx25519BlkNextSessionKey = 7,
		eECIESx25519BlkGalicClove = 11,
		eECIESx25519BlkPadding = 254	
	};	

    class ECIESX25519AEADRatchetSession: public GarlicRoutingSession
    {
        enum SessionState
        {
            eSessionStateNew =0,
            eSessionStateNewSessionReceived
        };

        public:

            typedef std::function<void (const uint8_t * buf, size_t len)> CloveHandler;

            ECIESX25519AEADRatchetSession (GarlicDestination * owner);
            ~ECIESX25519AEADRatchetSession ();

            std::shared_ptr<I2NPMessage> WrapSingleMessage (std::shared_ptr<const I2NPMessage> msg);

            bool NewIncomingSession (const uint8_t * buf, size_t len, CloveHandler handleClove);
            const uint8_t * GetRemoteStaticKey () const { return m_RemoteStaticKey; }
			void SetRemoteStaticKey (const uint8_t * key) { memcpy (m_RemoteStaticKey, key, 32); }

        private:

            void MixHash (const uint8_t * buf, size_t len);
            bool GenerateEphemeralKeysAndEncode (uint8_t * buf); // buf is 32 bytes

            void HandlePayload (const uint8_t * buf, size_t len,  CloveHandler& handleClove);

            bool NewOutgoingSessionMessage (const uint8_t * payload, size_t len, uint8_t * out, size_t outLen);
            bool NewSessionReplyMessage (const uint8_t * payload, size_t len, uint8_t * out, size_t outLen);
            std::vector<uint8_t> CreatePayload (std::shared_ptr<const I2NPMessage> msg);

        private:

            uint8_t m_H[32], m_CK[64] /* [chainkey, key] */, m_RemoteStaticKey[32];
            i2p::crypto::X25519Keys m_EphemeralKeys;
            SessionState m_State = eSessionStateNew;
            RatchetTagSet m_TagsetAB, m_TagsetBA;
    };
}
}

#endif