I2P: End-to-End encrypted and anonymous Internet https://i2pd.website/
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/*
* Copyright (c) 2013-2021, 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 <memory>
#include <openssl/rand.h>
#include <openssl/sha.h>
#include "Log.h"
#include "Transports.h"
#include "Timestamp.h"
#include "I2PEndian.h"
#include "I2NPProtocol.h"
#include "TunnelConfig.h"
namespace i2p
{
namespace tunnel
{
TunnelHopConfig::TunnelHopConfig (std::shared_ptr<const i2p::data::IdentityEx> r)
{
RAND_bytes ((uint8_t *)&tunnelID, 4);
if (!tunnelID) tunnelID = 1; // tunnelID can't be zero
isGateway = true;
isEndpoint = true;
ident = r;
//nextRouter = nullptr;
nextTunnelID = 0;
next = nullptr;
prev = nullptr;
}
void TunnelHopConfig::SetNextIdent (const i2p::data::IdentHash& ident)
{
nextIdent = ident;
isEndpoint = false;
RAND_bytes ((uint8_t *)&nextTunnelID, 4);
if (!nextTunnelID) nextTunnelID = 1; // tunnelID can't be zero
}
void TunnelHopConfig::SetReplyHop (uint32_t replyTunnelID, const i2p::data::IdentHash& replyIdent)
{
nextIdent = replyIdent;
nextTunnelID = replyTunnelID;
isEndpoint = true;
}
void TunnelHopConfig::SetNext (TunnelHopConfig * n)
{
next = n;
if (next)
{
next->prev = this;
next->isGateway = false;
isEndpoint = false;
nextIdent = next->ident->GetIdentHash ();
nextTunnelID = next->tunnelID;
}
}
void TunnelHopConfig::SetPrev (TunnelHopConfig * p)
{
prev = p;
if (prev)
{
prev->next = this;
prev->isEndpoint = false;
isGateway = false;
}
}
void TunnelHopConfig::DecryptRecord (uint8_t * records, int index) const
{
uint8_t * record = records + index*TUNNEL_BUILD_RECORD_SIZE;
i2p::crypto::CBCDecryption decryption;
decryption.SetKey (replyKey);
decryption.SetIV (replyIV);
decryption.Decrypt(record, TUNNEL_BUILD_RECORD_SIZE, record);
}
void ECIESTunnelHopConfig::EncryptECIES (const uint8_t * plainText, size_t len, uint8_t * encrypted)
{
if (!ident) return;
i2p::crypto::InitNoiseNState (*this, ident->GetEncryptionPublicKey ());
auto ephemeralKeys = i2p::transport::transports.GetNextX25519KeysPair ();
memcpy (encrypted, ephemeralKeys->GetPublicKey (), 32);
MixHash (encrypted, 32); // h = SHA256(h || sepk)
encrypted += 32;
uint8_t sharedSecret[32];
ephemeralKeys->Agree (ident->GetEncryptionPublicKey (), sharedSecret); // x25519(sesk, hepk)
MixKey (sharedSecret);
uint8_t nonce[12];
memset (nonce, 0, 12);
if (!i2p::crypto::AEADChaCha20Poly1305 (plainText, len, m_H, 32, m_CK + 32, nonce, encrypted, len + 16, true)) // encrypt
{
LogPrint (eLogWarning, "Tunnel: Plaintext AEAD encryption failed");
return;
}
MixHash (encrypted, len + 16); // h = SHA256(h || ciphertext)
}
bool ECIESTunnelHopConfig::DecryptECIES (const uint8_t * key, const uint8_t * nonce, const uint8_t * encrypted, size_t len, uint8_t * clearText) const
{
return i2p::crypto::AEADChaCha20Poly1305 (encrypted, len - 16, m_H, 32, key, nonce, clearText, len - 16, false); // decrypt
}
void LongECIESTunnelHopConfig::CreateBuildRequestRecord (uint8_t * records, uint32_t replyMsgID)
{
// generate keys
RAND_bytes (layerKey, 32);
RAND_bytes (ivKey, 32);
RAND_bytes (replyKey, 32);
RAND_bytes (replyIV, 16);
// fill clear text
uint8_t flag = 0;
if (isGateway) flag |= TUNNEL_BUILD_RECORD_GATEWAY_FLAG;
if (isEndpoint) flag |= TUNNEL_BUILD_RECORD_ENDPOINT_FLAG;
uint8_t clearText[ECIES_BUILD_REQUEST_RECORD_CLEAR_TEXT_SIZE];
htobe32buf (clearText + ECIES_BUILD_REQUEST_RECORD_RECEIVE_TUNNEL_OFFSET, tunnelID);
htobe32buf (clearText + ECIES_BUILD_REQUEST_RECORD_NEXT_TUNNEL_OFFSET, nextTunnelID);
memcpy (clearText + ECIES_BUILD_REQUEST_RECORD_NEXT_IDENT_OFFSET, nextIdent, 32);
memcpy (clearText + ECIES_BUILD_REQUEST_RECORD_LAYER_KEY_OFFSET, layerKey, 32);
memcpy (clearText + ECIES_BUILD_REQUEST_RECORD_IV_KEY_OFFSET, ivKey, 32);
memcpy (clearText + ECIES_BUILD_REQUEST_RECORD_REPLY_KEY_OFFSET, replyKey, 32);
memcpy (clearText + ECIES_BUILD_REQUEST_RECORD_REPLY_IV_OFFSET, replyIV, 16);
clearText[ECIES_BUILD_REQUEST_RECORD_FLAG_OFFSET] = flag;
memset (clearText + ECIES_BUILD_REQUEST_RECORD_MORE_FLAGS_OFFSET, 0, 3); // set to 0 for compatibility
htobe32buf (clearText + ECIES_BUILD_REQUEST_RECORD_REQUEST_TIME_OFFSET, i2p::util::GetMinutesSinceEpoch ());
htobe32buf (clearText + ECIES_BUILD_REQUEST_RECORD_REQUEST_EXPIRATION_OFFSET, 600); // +10 minutes
htobe32buf (clearText + ECIES_BUILD_REQUEST_RECORD_SEND_MSG_ID_OFFSET, replyMsgID);
memset (clearText + ECIES_BUILD_REQUEST_RECORD_PADDING_OFFSET, 0, ECIES_BUILD_REQUEST_RECORD_CLEAR_TEXT_SIZE - ECIES_BUILD_REQUEST_RECORD_PADDING_OFFSET);
// encrypt
uint8_t * record = records + recordIndex*TUNNEL_BUILD_RECORD_SIZE;
EncryptECIES (clearText, ECIES_BUILD_REQUEST_RECORD_CLEAR_TEXT_SIZE, record + BUILD_REQUEST_RECORD_ENCRYPTED_OFFSET);
memcpy (record + BUILD_REQUEST_RECORD_TO_PEER_OFFSET, (const uint8_t *)ident->GetIdentHash (), 16);
}
bool LongECIESTunnelHopConfig::DecryptBuildResponseRecord (uint8_t * records) const
{
uint8_t * record = records + recordIndex*TUNNEL_BUILD_RECORD_SIZE;
uint8_t nonce[12];
memset (nonce, 0, 12);
if (!DecryptECIES (m_CK, nonce, record, TUNNEL_BUILD_RECORD_SIZE, record))
{
LogPrint (eLogWarning, "Tunnel: Response AEAD decryption failed");
return false;
}
return true;
}
void ShortECIESTunnelHopConfig::CreateBuildRequestRecord (uint8_t * records, uint32_t replyMsgID)
{
// fill clear text
uint8_t flag = 0;
if (isGateway) flag |= TUNNEL_BUILD_RECORD_GATEWAY_FLAG;
if (isEndpoint) flag |= TUNNEL_BUILD_RECORD_ENDPOINT_FLAG;
uint8_t clearText[SHORT_REQUEST_RECORD_CLEAR_TEXT_SIZE ];
htobe32buf (clearText + SHORT_REQUEST_RECORD_RECEIVE_TUNNEL_OFFSET, tunnelID);
htobe32buf (clearText + SHORT_REQUEST_RECORD_NEXT_TUNNEL_OFFSET, nextTunnelID);
memcpy (clearText + SHORT_REQUEST_RECORD_NEXT_IDENT_OFFSET, nextIdent, 32);
clearText[SHORT_REQUEST_RECORD_FLAG_OFFSET] = flag;
memset (clearText + SHORT_REQUEST_RECORD_MORE_FLAGS_OFFSET, 0, 2);
clearText[SHORT_REQUEST_RECORD_LAYER_ENCRYPTION_TYPE] = 0; // AES
htobe32buf (clearText + SHORT_REQUEST_RECORD_REQUEST_TIME_OFFSET, i2p::util::GetMinutesSinceEpoch ());
htobe32buf (clearText + SHORT_REQUEST_RECORD_REQUEST_EXPIRATION_OFFSET , 600); // +10 minutes
htobe32buf (clearText + SHORT_REQUEST_RECORD_SEND_MSG_ID_OFFSET, replyMsgID);
memset (clearText + SHORT_REQUEST_RECORD_PADDING_OFFSET, 0, SHORT_REQUEST_RECORD_CLEAR_TEXT_SIZE - SHORT_REQUEST_RECORD_PADDING_OFFSET);
// encrypt
uint8_t * record = records + recordIndex*SHORT_TUNNEL_BUILD_RECORD_SIZE;
EncryptECIES (clearText, SHORT_REQUEST_RECORD_CLEAR_TEXT_SIZE, record + SHORT_REQUEST_RECORD_ENCRYPTED_OFFSET);
// derive keys
i2p::crypto::HKDF (m_CK, nullptr, 0, "SMTunnelReplyKey", m_CK);
memcpy (replyKey, m_CK + 32, 32);
i2p::crypto::HKDF (m_CK, nullptr, 0, "SMTunnelLayerKey", m_CK);
memcpy (layerKey, m_CK + 32, 32);
if (isEndpoint)
{
i2p::crypto::HKDF (m_CK, nullptr, 0, "TunnelLayerIVKey", m_CK);
memcpy (ivKey, m_CK + 32, 32);
i2p::crypto::HKDF (m_CK, nullptr, 0, "RGarlicKeyAndTag", m_CK); // OTBRM garlic key m_CK + 32, tag first 8 bytes of m_CK
}
else
memcpy (ivKey, m_CK, 32); // last HKDF
memcpy (record + BUILD_REQUEST_RECORD_TO_PEER_OFFSET, (const uint8_t *)ident->GetIdentHash (), 16);
}
bool ShortECIESTunnelHopConfig::DecryptBuildResponseRecord (uint8_t * records) const
{
uint8_t * record = records + recordIndex*SHORT_TUNNEL_BUILD_RECORD_SIZE;
uint8_t nonce[12];
memset (nonce, 0, 12);
nonce[4] = recordIndex; // nonce is record index
if (!DecryptECIES (replyKey, nonce, record, SHORT_TUNNEL_BUILD_RECORD_SIZE, record))
{
LogPrint (eLogWarning, "Tunnel: Response AEAD decryption failed");
return false;
}
return true;
}
void ShortECIESTunnelHopConfig::DecryptRecord (uint8_t * records, int index) const
{
uint8_t * record = records + index*SHORT_TUNNEL_BUILD_RECORD_SIZE;
uint8_t nonce[12];
memset (nonce, 0, 12);
nonce[4] = index; // nonce is index
i2p::crypto::ChaCha20 (record, SHORT_TUNNEL_BUILD_RECORD_SIZE, replyKey, nonce, record);
}
uint64_t ShortECIESTunnelHopConfig::GetGarlicKey (uint8_t * key) const
{
uint64_t tag;
memcpy (&tag, m_CK, 8);
memcpy (key, m_CK + 32, 32);
return tag;
}
void TunnelConfig::CreatePeers (const std::vector<std::shared_ptr<const i2p::data::IdentityEx> >& peers)
{
TunnelHopConfig * prev = nullptr;
for (const auto& it: peers)
{
TunnelHopConfig * hop = nullptr;
if (m_IsShort)
hop = new ShortECIESTunnelHopConfig (it);
else
{
if (it->GetCryptoKeyType () == i2p::data::CRYPTO_KEY_TYPE_ECIES_X25519_AEAD)
hop = new LongECIESTunnelHopConfig (it);
else
LogPrint (eLogError, "Tunnel: ElGamal router is not supported");
}
if (hop)
{
if (prev)
prev->SetNext (hop);
else
m_FirstHop = hop;
prev = hop;
}
}
m_LastHop = prev;
}
}
}