I2P: End-to-End encrypted and anonymous Internet https://i2pd.website/
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/*
* Copyright (c) 2013-2022, 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 "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);
uint8_t packet[1200]; // TODO: correct packet size
size_t packetSize = 64;
// fill packet
memcpy (packet + 32, m_EphemeralKeys->GetPublicKey (), 32); // X
// encrypt
CreateHeaderMask (m_Address->i, packet + (packetSize - 24), m_Address->i, packet + (packetSize - 12));
EncryptHeader (*(i2p::crypto::ChipherBlock *)packet);
uint8_t nonce[12] = {0};
i2p::crypto::ChaCha20 (packet + 16, 48, m_Address->i, nonce, packet + 16);
i2p::crypto::AEADChaCha20Poly1305 (packet + 64, packetSize - 64, m_NoiseState->m_H, 32, m_NoiseState->m_CK, nonce, packet + 64, packetSize - 48, true);
}
void SSU2Session::EncryptHeader (i2p::crypto::ChipherBlock& header)
{
header ^= m_HeaderMask;
}
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);
}
}
}