I2P: End-to-End encrypted and anonymous Internet https://i2pd.website/
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/*
* Copyright (c) 2022, 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
*/
#include <string.h>
#include <openssl/rand.h>
#include "Transports.h"
#include "SSU2.h"
namespace i2p
{
namespace transport
{
SSU2Session::SSU2Session (std::shared_ptr<const i2p::data::RouterInfo> in_RemoteRouter,
std::shared_ptr<const i2p::data::RouterInfo::Address> addr, bool peerTest):
TransportSession (in_RemoteRouter, SSU2_TERMINATION_TIMEOUT),
m_Address (addr)
{
m_NoiseState.reset (new i2p::crypto::NoiseSymmetricState);
if (in_RemoteRouter && addr)
{
// outgoing
InitNoiseXKState1 (*m_NoiseState, addr->s);
}
}
SSU2Session::~SSU2Session ()
{
}
void SSU2Session::SendSessionRequest ()
{
m_EphemeralKeys = i2p::transport::transports.GetNextX25519KeysPair ();
m_NoiseState->MixHash (m_EphemeralKeys->GetPublicKey (), 32);
uint8_t sharedSecret[32];
m_EphemeralKeys->Agree (m_Address->s, sharedSecret);
m_NoiseState->MixKey (sharedSecret);
Header header;
uint8_t headerX[48], payload[1200]; // TODO: correct payload size
size_t payloadSize = 8;
// fill packet
RAND_bytes (header.h.connID, 8);
memset (header.h.packetNum, 0, 4);
header.h.type = eSSU2SessionRequest;
header.h.flags[0] = 2; // ver
header.h.flags[1] = 2; // netID TODO:
header.h.flags[2] = 0; // flag
RAND_bytes (headerX, 8); // source id
memset (headerX + 8, 0, 8); // token
memcpy (headerX + 16, m_EphemeralKeys->GetPublicKey (), 32); // X
// encrypt
const uint8_t nonce[12] = {0};
i2p::crypto::AEADChaCha20Poly1305 (payload, payloadSize, m_NoiseState->m_H, 32, m_NoiseState->m_CK + 32, nonce, payload, payloadSize + 16, true);
payloadSize += 16;
CreateHeaderMask (m_Address->i, payload + (payloadSize - 24), m_Address->i, payload + (payloadSize - 12));
EncryptHeader (header);
i2p::crypto::ChaCha20 (headerX, 48, m_Address->i, nonce, headerX);
}
void SSU2Session::EncryptHeader (Header& h)
{
h.ll[0] ^= m_HeaderMask.ll[0];
h.ll[1] ^= m_HeaderMask.ll[1];
}
void SSU2Session::CreateHeaderMask (const uint8_t * kh1, const uint8_t * nonce1, const uint8_t * kh2, const uint8_t * nonce2)
{
// Header Encryption KDF
uint8_t data[8] = {0};
i2p::crypto::ChaCha20 (data, 8, kh1, nonce1, m_HeaderMask.buf);
i2p::crypto::ChaCha20 (data, 8, kh2, nonce2, m_HeaderMask.buf + 8);
}
}
}