I2P: End-to-End encrypted and anonymous Internet https://i2pd.website/
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#include <openssl/rand.h>
#include <openssl/sha.h>
#include <openssl/hmac.h>
#include <stdlib.h>
#include "Log.h"
#include "I2PEndian.h"
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#include "Crypto.h"
#include "Ed25519.h"
#include "NTCP2.h"
namespace i2p
{
namespace transport
{
NTCP2Session::NTCP2Session (NTCP2Server& server, std::shared_ptr<const i2p::data::RouterInfo> in_RemoteRouter):
TransportSession (in_RemoteRouter, 30),
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m_Server (server), m_Socket (m_Server.GetService ()),
m_IsEstablished (false), m_IsTerminated (false),
m_SessionRequestBuffer (nullptr), m_SessionCreatedBuffer (nullptr)
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{
auto addr = in_RemoteRouter->GetNTCPAddress ();
if (addr->ntcp2)
{
memcpy (m_RemoteStaticKey, addr->ntcp2->staticKey, 32);
memcpy (m_RemoteIV, addr->ntcp2->iv, 16);
}
else
LogPrint (eLogWarning, "NTCP2: Missing NTCP2 parameters");
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}
NTCP2Session::~NTCP2Session ()
{
delete[] m_SessionRequestBuffer;
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delete[] m_SessionCreatedBuffer;
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}
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void NTCP2Session::Terminate ()
{
if (!m_IsTerminated)
{
m_IsTerminated = true;
m_IsEstablished = false;
m_Socket.close ();
LogPrint (eLogDebug, "NTCP2: session terminated");
}
}
void NTCP2Session::Done ()
{
m_Server.GetService ().post (std::bind (&NTCP2Session::Terminate, shared_from_this ()));
}
bool NTCP2Session::KeyDerivationFunction1 (const uint8_t * rs, const uint8_t * pub, uint8_t * derived, uint8_t * ad)
{
static const char protocolName[] = "Noise_XK_25519_ChaChaPoly_SHA256"; // 32 bytes
uint8_t h[64], ck[33];
memcpy (ck, protocolName, 32);
SHA256 ((const uint8_t *)protocolName, 32, h);
// h = SHA256(h || rs)
memcpy (h + 32, rs, 32);
SHA256 (h, 64, h);
// h = SHA256(h || pub)
memcpy (h + 32, pub, 32);
SHA256 (h, 64, ad);
// x25519 between rs and priv
uint8_t inputKeyMaterial[32];
BN_CTX * ctx = BN_CTX_new ();
i2p::crypto::GetEd25519 ()->ScalarMul (rs, m_ExpandedPrivateKey, inputKeyMaterial, ctx); // rs*priv
BN_CTX_free (ctx);
// temp_key = HMAC-SHA256(ck, input_key_material)
uint8_t tempKey[32]; unsigned int len;
HMAC(EVP_sha256(), ck, 32, inputKeyMaterial, 32, tempKey, &len);
// ck = HMAC-SHA256(temp_key, byte(0x01))
inputKeyMaterial[0] = 1;
HMAC(EVP_sha256(), tempKey, 32, inputKeyMaterial, 1, ck, &len);
// derived = HMAC-SHA256(temp_key, ck || byte(0x02))
ck[32] = 2;
HMAC(EVP_sha256(), tempKey, 32, ck, 33, derived, &len);
return true;
}
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void NTCP2Session::CreateEphemeralKey (uint8_t * pub)
{
uint8_t key[32];
RAND_bytes (key, 32);
i2p::crypto::Ed25519::ExpandPrivateKey (key, m_ExpandedPrivateKey);
BN_CTX * ctx = BN_CTX_new ();
i2p::crypto::GetEd25519 ()->ScalarMulB (m_ExpandedPrivateKey, pub, ctx);
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BN_CTX_free (ctx);
}
void NTCP2Session::SendSessionRequest ()
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{
// create buffer and fill padding
auto paddingLength = rand () % (287 - 64); // message length doesn't exceed 287 bytes
m_SessionRequestBuffer = new uint8_t[paddingLength + 64];
RAND_bytes (m_SessionRequestBuffer + 64, paddingLength);
// generate key pair (X)
uint8_t x[32];
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CreateEphemeralKey (x);
// encrypt X
i2p::crypto::CBCEncryption encryption;
encryption.SetKey (GetRemoteIdentity ()->GetIdentHash ());
encryption.SetIV (m_RemoteIV);
encryption.Encrypt (x, 32, m_SessionRequestBuffer);
// encryption key for next block
uint8_t key[32], ad[32];
KeyDerivationFunction1 (m_RemoteStaticKey, x, key, ad);
// fill options
uint8_t options[32]; // actual options size is 16 bytes
memset (options, 0, 16);
htobe16buf (options, 2); // ver
htobe16buf (options + 2, paddingLength); // padLen
htobe16buf (options + 4, 0); // m3p2Len TODO:
// 2 bytes reserved
htobe32buf (options + 8, i2p::util::GetSecondsSinceEpoch ()); // tsA
// 4 bytes reserved
// sign and encrypt options
uint8_t nonce[12];
memset (nonce, 0, 12); // set nonce to zero
i2p::crypto::AEADChaCha20Poly1305Encrypt (options, 16, ad, 32, key, nonce, m_SessionRequestBuffer + 32, 32);
// send message
boost::asio::async_write (m_Socket, boost::asio::buffer (m_SessionRequestBuffer, paddingLength + 64), boost::asio::transfer_all (),
std::bind(&NTCP2Session::HandleSessionRequestSent, shared_from_this (), std::placeholders::_1, std::placeholders::_2));
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}
void NTCP2Session::HandleSessionRequestSent (const boost::system::error_code& ecode, std::size_t bytes_transferred)
{
(void) bytes_transferred;
delete[] m_SessionRequestBuffer; m_SessionRequestBuffer = nullptr;
if (ecode)
{
LogPrint (eLogInfo, "NTCP2: couldn't send SessionRequest message: ", ecode.message ());
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Terminate ();
}
else
{
m_SessionCreatedBuffer = new uint8_t[287]; // TODO: determine actual max size
// we receive first 56 bytes (32 Y, and 24 ChaCha/Poly frame) first
boost::asio::async_read (m_Socket, boost::asio::buffer(m_SessionCreatedBuffer, sizeof (56)), boost::asio::transfer_all (),
std::bind(&NTCP2Session::HandleSessionCreatedReceived, shared_from_this (), std::placeholders::_1, std::placeholders::_2));
}
}
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void NTCP2Session::HandleSessionCreatedReceived (const boost::system::error_code& ecode, std::size_t bytes_transferred)
{
(void) bytes_transferred;
delete[] m_SessionCreatedBuffer; m_SessionCreatedBuffer = nullptr;
if (ecode)
LogPrint (eLogInfo, "NTCP2: SessionCreated read error: ", ecode.message ());
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Terminate (); // TODO: continue
}
void NTCP2Session::ClientLogin ()
{
SendSessionRequest ();
}
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NTCP2Server::NTCP2Server ():
m_IsRunning (false), m_Thread (nullptr), m_Work (m_Service)
{
}
NTCP2Server::~NTCP2Server ()
{
Stop ();
}
void NTCP2Server::Start ()
{
if (!m_IsRunning)
{
m_IsRunning = true;
m_Thread = new std::thread (std::bind (&NTCP2Server::Run, this));
}
}
void NTCP2Server::Stop ()
{
if (m_IsRunning)
{
m_IsRunning = false;
m_Service.stop ();
if (m_Thread)
{
m_Thread->join ();
delete m_Thread;
m_Thread = nullptr;
}
}
}
void NTCP2Server::Run ()
{
while (m_IsRunning)
{
try
{
m_Service.run ();
}
catch (std::exception& ex)
{
LogPrint (eLogError, "NTCP2: runtime exception: ", ex.what ());
}
}
}
void NTCP2Server::Connect(const boost::asio::ip::address & address, uint16_t port, std::shared_ptr<NTCP2Session> conn)
{
LogPrint (eLogDebug, "NTCP2: Connecting to ", address ,":", port);
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m_Service.post([this, address, port, conn]()
{
conn->GetSocket ().async_connect (boost::asio::ip::tcp::endpoint (address, port), std::bind (&NTCP2Server::HandleConnect, this, std::placeholders::_1, conn));
});
}
void NTCP2Server::HandleConnect (const boost::system::error_code& ecode, std::shared_ptr<NTCP2Session> conn)
{
if (ecode)
{
LogPrint (eLogInfo, "NTCP2: Connect error ", ecode.message ());
conn->Terminate ();
}
else
{
LogPrint (eLogDebug, "NTCP2: Connected to ", conn->GetSocket ().remote_endpoint ());
conn->ClientLogin ();
}
}
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}
}