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/*
* Copyright (c) 2013-2020, The PurpleI2P Project
*
* This file is part of Purple i2pd project and licensed under BSD3
*
* See full license text in LICENSE file at top of project tree
*/
#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 <list>
#include <unordered_map>
#include "Identity.h"
#include "Crypto.h"
#include "Garlic.h"
#include "Tag.h"
namespace i2p
{
namespace garlic
{
const int ECIESX25519_RESTART_TIMEOUT = 120; // number of second since session creation we can restart session after
const int ECIESX25519_EXPIRATION_TIMEOUT = 480; // in seconds
const int ECIESX25519_INACTIVITY_TIMEOUT = 90; // number of second we receive nothing and should restart if we can
const int ECIESX25519_INCOMING_TAGS_EXPIRATION_TIMEOUT = 600; // in seconds
const int ECIESX25519_PREVIOUS_TAGSET_EXPIRATION_TIMEOUT = 180; // 180
const int ECIESX25519_TAGSET_MAX_NUM_TAGS = 4096; // number of tags we request new tagset after
const int ECIESX25519_MIN_NUM_GENERATED_TAGS = 24;
const int ECIESX25519_MAX_NUM_GENERATED_TAGS = 160;
const int ECIESX25519_NSR_NUM_GENERATED_TAGS = 12;
const size_t ECIESX25519_OPTIMAL_PAYLOAD_SIZE = 1912; // 1912 = 1956 /* to fit 2 tunnel messages */
// - 16 /* I2NP header */ - 16 /* poly hash */ - 8 /* tag */ - 4 /* garlic length */
class ECIESX25519AEADRatchetSession;
class RatchetTagSet
{
public:
RatchetTagSet (std::shared_ptr<ECIESX25519AEADRatchetSession> session): m_Session (session) {};
void DHInitialize (const uint8_t * rootKey, const uint8_t * k);
void NextSessionTagRatchet ();
uint64_t GetNextSessionTag ();
const uint8_t * GetNextRootKey () const { return m_NextRootKey; };
int GetNextIndex () const { return m_NextIndex; };
void GetSymmKey (int index, uint8_t * key);
std::shared_ptr<ECIESX25519AEADRatchetSession> GetSession () { return m_Session.lock (); };
int GetTagSetID () const { return m_TagSetID; };
void SetTagSetID (int tagsetID) { m_TagSetID = tagsetID; };
void Expire ();
bool IsExpired (uint64_t ts) const { return m_ExpirationTimestamp && ts > m_ExpirationTimestamp; };
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], m_NextRootKey[32];
int m_NextIndex, m_NextSymmKeyIndex;
std::unordered_map<int, i2p::data::Tag<32> > m_ItermediateSymmKeys;
std::weak_ptr<ECIESX25519AEADRatchetSession> m_Session;
int m_TagSetID = 0;
uint64_t m_ExpirationTimestamp = 0;
};
enum ECIESx25519BlockType
{
eECIESx25519BlkDateTime = 0,
eECIESx25519BlkSessionID = 1,
eECIESx25519BlkTermination = 4,
eECIESx25519BlkOptions = 5,
eECIESx25519BlkNextKey = 7,
eECIESx25519BlkAck = 8,
eECIESx25519BlkAckRequest = 9,
eECIESx25519BlkGalicClove = 11,
eECIESx25519BlkPadding = 254
};
const uint8_t ECIESX25519_NEXT_KEY_KEY_PRESENT_FLAG = 0x01;
const uint8_t ECIESX25519_NEXT_KEY_REVERSE_KEY_FLAG = 0x02;
const uint8_t ECIESX25519_NEXT_KEY_REQUEST_REVERSE_KEY_FLAG = 0x04;
class ECIESX25519AEADRatchetSession: public GarlicRoutingSession, public std::enable_shared_from_this<ECIESX25519AEADRatchetSession>
{
enum SessionState
{
eSessionStateNew = 0,
eSessionStateNewSessionReceived,
eSessionStateNewSessionSent,
eSessionStateNewSessionReplySent,
eSessionStateEstablished
};
5 years ago
struct DHRatchet
{
int keyID = 0;
i2p::crypto::X25519Keys key;
uint8_t remote[32]; // last remote public key
bool newKey = true;
};
public:
ECIESX25519AEADRatchetSession (GarlicDestination * owner, bool attachLeaseSet);
~ECIESX25519AEADRatchetSession ();
bool HandleNextMessage (uint8_t * buf, size_t len, std::shared_ptr<RatchetTagSet> receiveTagset, 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 CheckExpired (uint64_t ts); // true is expired
bool CanBeRestarted (uint64_t ts) const { return ts > m_SessionCreatedTimestamp + ECIESX25519_RESTART_TIMEOUT; }
bool IsInactive (uint64_t ts) const { return ts > m_LastActivityTimestamp + ECIESX25519_INACTIVITY_TIMEOUT && CanBeRestarted (ts); }
bool IsRatchets () const { return true; };
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
std::shared_ptr<RatchetTagSet> CreateNewSessionTagset ();
bool HandleNewIncomingSession (const uint8_t * buf, size_t len);
bool HandleNewOutgoingSessionReply (uint8_t * buf, size_t len);
bool HandleExistingSessionMessage (uint8_t * buf, size_t len, std::shared_ptr<RatchetTagSet> receiveTagset, int index);
void HandlePayload (const uint8_t * buf, size_t len, const std::shared_ptr<RatchetTagSet>& receiveTagset, int index);
void HandleNextKey (const uint8_t * buf, size_t len, const std::shared_ptr<RatchetTagSet>& receiveTagset);
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 NextNewSessionReplyMessage (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);
std::vector<uint8_t> CreatePayload (std::shared_ptr<const I2NPMessage> msg, bool first);
size_t CreateGarlicClove (std::shared_ptr<const I2NPMessage> msg, uint8_t * buf, size_t len, bool isDestination = false);
size_t CreateLeaseSetClove (std::shared_ptr<const i2p::data::LocalLeaseSet> ls, uint64_t ts, uint8_t * buf, size_t len);
void GenerateMoreReceiveTags (std::shared_ptr<RatchetTagSet> receiveTagset, int numTags);
void NewNextSendRatchet ();
private:
uint8_t m_H[32], m_CK[64] /* [chainkey, key] */, m_RemoteStaticKey[32];
uint8_t m_Aepk[32]; // Alice's ephemeral keys, for incoming only
uint8_t m_NSREncodedKey[32], m_NSRH[32], m_NSRKey[32]; // new session reply, for incoming only
i2p::crypto::X25519Keys m_EphemeralKeys;
SessionState m_State = eSessionStateNew;
uint64_t m_SessionCreatedTimestamp = 0, m_LastActivityTimestamp = 0; // incoming
std::shared_ptr<RatchetTagSet> m_SendTagset, m_NSRTagset;
std::unique_ptr<i2p::data::IdentHash> m_Destination;// TODO: might not need it
std::list<std::pair<uint16_t, int> > m_AckRequests; // (tagsetid, index)
bool m_SendReverseKey = false, m_SendForwardKey = false;
std::unique_ptr<DHRatchet> m_NextReceiveRatchet, m_NextSendRatchet;
public:
// for HTTP only
int GetState () const { return (int)m_State; }
i2p::data::IdentHash GetDestination () const
{
return m_Destination ? *m_Destination : i2p::data::IdentHash ();
}
};
std::shared_ptr<I2NPMessage> WrapECIESX25519AEADRatchetMessage (std::shared_ptr<const I2NPMessage> msg, const uint8_t * key, uint64_t tag);
}
}
#endif