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#ifndef ECIES_X25519_AEAD_RATCHET_SESSION_H__
#define ECIES_X25519_AEAD_RATCHET_SESSION_H__
#include <string.h>
#include <inttypes.h>
#include <functional>
#include <memory>
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#include <vector>
#include "Identity.h"
#include "Crypto.h"
#include "Garlic.h"
namespace i2p
{
namespace garlic
{
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class RatchetTagSet
{
public:
void DHInitialize (const uint8_t * rootKey, const uint8_t * k);
void NextSessionTagRatchet ();
uint64_t GetNextSessionTag ();
int GetNextIndex () const { return m_NextIndex; };
const uint8_t * GetSymmKey (int index);
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private:
void CalculateSymmKeyCK (int index);
private:
union
{
uint64_t ll[8];
uint8_t buf[64];
const uint8_t * GetSessTagCK () const { return buf; }; // sessTag_chainKey = keydata[0:31]
const uint8_t * GetSessTagConstant () const { return buf + 32; }; // SESSTAG_CONSTANT = keydata[32:63]
uint64_t GetTag () const { return ll[4]; }; // tag = keydata[32:39]
} m_KeyData;
uint8_t m_SessTagConstant[32], m_SymmKeyCK[32], m_CurrentSymmKeyCK[64];
int m_NextIndex, m_NextSymmKeyIndex;
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};
enum ECIESx25519BlockType
{
eECIESx25519BlkDateTime = 0,
eECIESx25519BlkSessionID = 1,
eECIESx25519BlkTermination = 4,
eECIESx25519BlkOptions = 5,
eECIESx25519BlkNextSessionKey = 7,
eECIESx25519BlkGalicClove = 11,
eECIESx25519BlkPadding = 254
};
const int ECIESX25519_RESTART_TIMEOUT = 120; // number of second of inactivity we should restart after
const int ECIESX25519_EXPIRATION_TIMEOUT = 600; // in seconds
class ECIESX25519AEADRatchetSession: public GarlicRoutingSession, public std::enable_shared_from_this<ECIESX25519AEADRatchetSession>
{
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enum SessionState
{
eSessionStateNew =0,
eSessionStateNewSessionReceived,
eSessionStateNewSessionSent,
eSessionStateEstablished
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};
public:
ECIESX25519AEADRatchetSession (GarlicDestination * owner);
~ECIESX25519AEADRatchetSession ();
bool HandleNextMessage (const uint8_t * buf, size_t len, int index = 0);
std::shared_ptr<I2NPMessage> WrapSingleMessage (std::shared_ptr<const I2NPMessage> msg);
const uint8_t * GetRemoteStaticKey () const { return m_RemoteStaticKey; }
void SetRemoteStaticKey (const uint8_t * key) { memcpy (m_RemoteStaticKey, key, 32); }
void SetDestination (const i2p::data::IdentHash& dest) // TODO:
{
if (!m_Destination) m_Destination.reset (new i2p::data::IdentHash (dest));
}
bool IsExpired (uint64_t ts) const { return ts > m_LastActivityTimestamp + ECIESX25519_EXPIRATION_TIMEOUT; }
bool CanBeRestarted (uint64_t ts) const { return ts > m_LastActivityTimestamp + ECIESX25519_RESTART_TIMEOUT; }
private:
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void ResetKeys ();
void MixHash (const uint8_t * buf, size_t len);
void CreateNonce (uint64_t seqn, uint8_t * nonce);
bool GenerateEphemeralKeysAndEncode (uint8_t * buf); // buf is 32 bytes
uint64_t CreateNewSessionTag () const;
bool HandleNewIncomingSession (const uint8_t * buf, size_t len);
bool HandleNewOutgoingSessionReply (const uint8_t * buf, size_t len);
bool HandleExistingSessionMessage (const uint8_t * buf, size_t len, int index);
void HandlePayload (const uint8_t * buf, size_t len);
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);
bool NewExistingSessionMessage (const uint8_t * payload, size_t len, uint8_t * out, size_t outLen);
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std::vector<uint8_t> CreatePayload (std::shared_ptr<const I2NPMessage> msg);
size_t CreateGarlicClove (std::shared_ptr<const I2NPMessage> msg, uint8_t * buf, size_t len, bool isDestination = false);
void GenerateMoreReceiveTags (int numTags);
private:
uint8_t m_H[32], m_CK[64] /* [chainkey, key] */, m_RemoteStaticKey[32];
uint8_t m_Aepk[32]; // Alice's ephemeral keys TODO: for incoming only
i2p::crypto::X25519Keys m_EphemeralKeys;
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SessionState m_State = eSessionStateNew;
uint64_t m_LastActivityTimestamp = 0; // incoming
RatchetTagSet m_SendTagset, m_ReceiveTagset;
int m_NumReceiveTags = 0;
std::unique_ptr<i2p::data::IdentHash> m_Destination;// TODO: might not need it
};
}
}
#endif