I2P: End-to-End encrypted and anonymous Internet https://i2pd.website/
 
 
 
 
 

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/*
* Copyright (c) 2013-2023, 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 "I2PEndian.h"
#include "Crypto.h"
#include "Log.h"
#include "Tag.h"
#include "Timestamp.h"
#include "NetDb.hpp"
#include "Tunnel.h"
#include "LeaseSet.h"
namespace i2p
{
namespace data
{
LeaseSet::LeaseSet (bool storeLeases):
m_IsValid (false), m_StoreLeases (storeLeases), m_ExpirationTime (0), m_EncryptionKey (nullptr),
m_Buffer (nullptr), m_BufferLen (0)
{
}
LeaseSet::LeaseSet (const uint8_t * buf, size_t len, bool storeLeases):
m_IsValid (true), m_StoreLeases (storeLeases), m_ExpirationTime (0), m_EncryptionKey (nullptr)
{
m_Buffer = new uint8_t[len];
memcpy (m_Buffer, buf, len);
m_BufferLen = len;
ReadFromBuffer ();
}
void LeaseSet::Update (const uint8_t * buf, size_t len, bool verifySignature)
{
SetBuffer (buf, len);
ReadFromBuffer (false, verifySignature);
}
void LeaseSet::PopulateLeases ()
{
m_StoreLeases = true;
ReadFromBuffer (false);
}
void LeaseSet::ReadFromBuffer (bool readIdentity, bool verifySignature)
{
if (readIdentity || !m_Identity)
m_Identity = netdb.NewIdentity (m_Buffer, m_BufferLen);
size_t size = m_Identity->GetFullLen ();
if (size + 256 > m_BufferLen)
{
LogPrint (eLogError, "LeaseSet: Identity length ", int(size), " exceeds buffer size ", int(m_BufferLen));
m_IsValid = false;
return;
}
if (m_StoreLeases)
{
if (!m_EncryptionKey) m_EncryptionKey = new uint8_t[256];
memcpy (m_EncryptionKey, m_Buffer + size, 256);
}
size += 256; // encryption key
size += m_Identity->GetSigningPublicKeyLen (); // unused signing key
if (size + 1 > m_BufferLen)
{
LogPrint (eLogError, "LeaseSet: ", int(size), " exceeds buffer size ", int(m_BufferLen));
m_IsValid = false;
return;
}
uint8_t num = m_Buffer[size];
size++; // num
LogPrint (eLogDebug, "LeaseSet: Read num=", (int)num);
if (!num || num > MAX_NUM_LEASES)
{
LogPrint (eLogError, "LeaseSet: Incorrect number of leases", (int)num);
m_IsValid = false;
return;
}
if (size + num*LEASE_SIZE > m_BufferLen)
{
LogPrint (eLogError, "LeaseSet: ", int(size), " exceeds buffer size ", int(m_BufferLen));
m_IsValid = false;
return;
}
UpdateLeasesBegin ();
// process leases
m_ExpirationTime = 0;
auto ts = i2p::util::GetMillisecondsSinceEpoch ();
const uint8_t * leases = m_Buffer + size;
for (int i = 0; i < num; i++)
{
Lease lease;
lease.tunnelGateway = leases;
leases += 32; // gateway
lease.tunnelID = bufbe32toh (leases);
leases += 4; // tunnel ID
lease.endDate = bufbe64toh (leases);
leases += 8; // end date
UpdateLease (lease, ts);
}
if (!m_ExpirationTime)
{
LogPrint (eLogWarning, "LeaseSet: All leases are expired. Dropped");
m_IsValid = false;
return;
}
m_ExpirationTime += LEASE_ENDDATE_THRESHOLD;
UpdateLeasesEnd ();
// verify
if (verifySignature)
{
auto signedSize = leases - m_Buffer;
if (signedSize + m_Identity->GetSignatureLen () > m_BufferLen)
{
LogPrint (eLogError, "LeaseSet: Signature exceeds buffer size ", int(m_BufferLen));
m_IsValid = false;
}
else if (!m_Identity->Verify (m_Buffer, signedSize, leases))
{
LogPrint (eLogWarning, "LeaseSet: Verification failed");
m_IsValid = false;
}
}
}
void LeaseSet::UpdateLeasesBegin ()
{
// reset existing leases
if (m_StoreLeases)
for (auto& it: m_Leases)
it->isUpdated = false;
else
m_Leases.clear ();
}
void LeaseSet::UpdateLeasesEnd ()
{
// delete old leases
if (m_StoreLeases)
{
for (auto it = m_Leases.begin (); it != m_Leases.end ();)
{
if (!(*it)->isUpdated)
{
(*it)->endDate = 0; // somebody might still hold it
m_Leases.erase (it++);
}
else
++it;
}
}
}
void LeaseSet::UpdateLease (const Lease& lease, uint64_t ts)
{
if (ts < lease.endDate + LEASE_ENDDATE_THRESHOLD)
{
if (lease.endDate > m_ExpirationTime)
m_ExpirationTime = lease.endDate;
if (m_StoreLeases)
{
auto ret = m_Leases.insert (i2p::data::netdb.NewLease (lease));
if (!ret.second) (*ret.first)->endDate = lease.endDate; // update existing
(*ret.first)->isUpdated = true;
}
}
else
LogPrint (eLogWarning, "LeaseSet: Lease is expired already");
}
uint64_t LeaseSet::ExtractExpirationTimestamp (const uint8_t * buf, size_t len) const
{
if (!m_Identity) return 0;
size_t size = m_Identity->GetFullLen ();
if (size > len) return 0;
size += 256; // encryption key
size += m_Identity->GetSigningPublicKeyLen (); // unused signing key
if (size > len) return 0;
uint8_t num = buf[size];
size++; // num
if (size + num*LEASE_SIZE > len) return 0;
uint64_t timestamp= 0 ;
for (int i = 0; i < num; i++)
{
size += 36; // gateway (32) + tunnelId(4)
auto endDate = bufbe64toh (buf + size);
size += 8; // end date
if (!timestamp || endDate < timestamp)
timestamp = endDate;
}
return timestamp;
}
bool LeaseSet::IsNewer (const uint8_t * buf, size_t len) const
{
return ExtractExpirationTimestamp (buf, len) > ExtractExpirationTimestamp (m_Buffer, m_BufferLen);
}
bool LeaseSet::ExpiresSoon(const uint64_t dlt, const uint64_t fudge) const
{
auto now = i2p::util::GetMillisecondsSinceEpoch ();
if (fudge) now += rand() % fudge;
if (now >= m_ExpirationTime) return true;
return m_ExpirationTime - now <= dlt;
}
const std::vector<std::shared_ptr<const Lease> > LeaseSet::GetNonExpiredLeases (bool withThreshold) const
{
return GetNonExpiredLeasesExcluding( [] (const Lease & l) -> bool { return false; }, withThreshold);
}
const std::vector<std::shared_ptr<const Lease> > LeaseSet::GetNonExpiredLeasesExcluding (LeaseInspectFunc exclude, bool withThreshold) const
{
auto ts = i2p::util::GetMillisecondsSinceEpoch ();
std::vector<std::shared_ptr<const Lease> > leases;
for (const auto& it: m_Leases)
{
auto endDate = it->endDate;
if (withThreshold)
endDate += LEASE_ENDDATE_THRESHOLD;
else
endDate -= LEASE_ENDDATE_THRESHOLD;
if (ts < endDate && !exclude(*it))
leases.push_back (it);
}
return leases;
}
bool LeaseSet::HasExpiredLeases () const
{
auto ts = i2p::util::GetMillisecondsSinceEpoch ();
for (const auto& it: m_Leases)
if (ts >= it->endDate) return true;
return false;
}
bool LeaseSet::IsExpired () const
{
if (m_StoreLeases && IsEmpty ()) return true;
auto ts = i2p::util::GetMillisecondsSinceEpoch ();
return ts > m_ExpirationTime;
}
void LeaseSet::Encrypt (const uint8_t * data, uint8_t * encrypted) const
{
if (!m_EncryptionKey) return;
auto encryptor = m_Identity->CreateEncryptor (m_EncryptionKey);
if (encryptor)
encryptor->Encrypt (data, encrypted);
}
void LeaseSet::SetBuffer (const uint8_t * buf, size_t len)
{
if (len > MAX_LS_BUFFER_SIZE)
{
LogPrint (eLogError, "LeaseSet: Buffer is too long ", len);
len = MAX_LS_BUFFER_SIZE;
}
if (m_Buffer && len > m_BufferLen)
{
delete[] m_Buffer;
m_Buffer = nullptr;
}
if (!m_Buffer)
m_Buffer = new uint8_t[len];
m_BufferLen = len;
memcpy (m_Buffer, buf, len);
}
void LeaseSet::SetBufferLen (size_t len)
{
if (len <= m_BufferLen) m_BufferLen = len;
else
LogPrint (eLogError, "LeaseSet2: Actual buffer size ", int(len) , " exceeds full buffer size ", int(m_BufferLen));
}
LeaseSet2::LeaseSet2 (uint8_t storeType, const uint8_t * buf, size_t len, bool storeLeases, CryptoKeyType preferredCrypto):
LeaseSet (storeLeases), m_StoreType (storeType), m_EncryptionType (preferredCrypto)
{
SetBuffer (buf, len);
if (storeType == NETDB_STORE_TYPE_ENCRYPTED_LEASESET2)
ReadFromBufferEncrypted (buf, len, nullptr, nullptr);
else
ReadFromBuffer (buf, len);
}
LeaseSet2::LeaseSet2 (const uint8_t * buf, size_t len, std::shared_ptr<const BlindedPublicKey> key,
const uint8_t * secret, CryptoKeyType preferredCrypto):
LeaseSet (true), m_StoreType (NETDB_STORE_TYPE_ENCRYPTED_LEASESET2), m_EncryptionType (preferredCrypto)
{
ReadFromBufferEncrypted (buf, len, key, secret);
}
void LeaseSet2::Update (const uint8_t * buf, size_t len, bool verifySignature)
{
SetBuffer (buf, len);
if (GetStoreType () != NETDB_STORE_TYPE_ENCRYPTED_LEASESET2)
ReadFromBuffer (buf, len, false, verifySignature);
// TODO: implement encrypted
}
bool LeaseSet2::IsNewer (const uint8_t * buf, size_t len) const
{
uint64_t expiration;
return ExtractPublishedTimestamp (buf, len, expiration) > m_PublishedTimestamp;
}
void LeaseSet2::ReadFromBuffer (const uint8_t * buf, size_t len, bool readIdentity, bool verifySignature)
{
// standard LS2 header
std::shared_ptr<const IdentityEx> identity;
if (readIdentity || !GetIdentity ())
{
identity = netdb.NewIdentity (buf, len);
SetIdentity (identity);
}
else
identity = GetIdentity ();
size_t offset = identity->GetFullLen ();
if (offset + 8 > len) return;
m_PublishedTimestamp = bufbe32toh (buf + offset); offset += 4; // published timestamp (seconds)
uint16_t expires = bufbe16toh (buf + offset); offset += 2; // expires (seconds)
SetExpirationTime ((m_PublishedTimestamp + expires)*1000LL); // in milliseconds
uint16_t flags = bufbe16toh (buf + offset); offset += 2; // flags
if (flags & LEASESET2_FLAG_OFFLINE_KEYS)
{
// transient key
m_TransientVerifier = ProcessOfflineSignature (identity, buf, len, offset);
if (!m_TransientVerifier)
{
LogPrint (eLogError, "LeaseSet2: Offline signature failed");
return;
}
}
if (flags & LEASESET2_FLAG_UNPUBLISHED_LEASESET) m_IsPublic = false;
if (flags & LEASESET2_FLAG_PUBLISHED_ENCRYPTED)
{
m_IsPublishedEncrypted = true;
m_IsPublic = true;
}
// type specific part
size_t s = 0;
switch (m_StoreType)
{
case NETDB_STORE_TYPE_STANDARD_LEASESET2:
s = ReadStandardLS2TypeSpecificPart (buf + offset, len - offset);
break;
case NETDB_STORE_TYPE_META_LEASESET2:
s = ReadMetaLS2TypeSpecificPart (buf + offset, len - offset);
break;
default:
LogPrint (eLogWarning, "LeaseSet2: Unexpected store type ", (int)m_StoreType);
}
if (!s) return;
offset += s;
if (verifySignature || m_TransientVerifier)
{
// verify signature
bool verified = m_TransientVerifier ? VerifySignature (m_TransientVerifier, buf, len, offset) :
VerifySignature (identity, buf, len, offset);
SetIsValid (verified);
}
else
SetIsValid (true);
offset += m_TransientVerifier ? m_TransientVerifier->GetSignatureLen () : identity->GetSignatureLen ();
if (offset > len) {
LogPrint (eLogWarning, "LeaseSet2: short buffer: wanted ", int(offset), "bytes, have ", int(len));
return;
}
SetBufferLen (offset);
}
template<typename Verifier>
bool LeaseSet2::VerifySignature (Verifier& verifier, const uint8_t * buf, size_t len, size_t signatureOffset)
{
if (signatureOffset + verifier->GetSignatureLen () > len) return false;
// we assume buf inside DatabaseStore message, so buf[-1] is valid memory
// change it for signature verification, and restore back
uint8_t c = buf[-1];
const_cast<uint8_t *>(buf)[-1] = m_StoreType;
bool verified = verifier->Verify (buf - 1, signatureOffset + 1, buf + signatureOffset);
const_cast<uint8_t *>(buf)[-1] = c;
if (!verified)
LogPrint (eLogWarning, "LeaseSet2: Verification failed");
return verified;
}
size_t LeaseSet2::ReadStandardLS2TypeSpecificPart (const uint8_t * buf, size_t len)
{
size_t offset = 0;
// properties
uint16_t propertiesLen = bufbe16toh (buf + offset); offset += 2;
offset += propertiesLen; // skip for now. TODO: implement properties
// key sections
CryptoKeyType preferredKeyType = m_EncryptionType;
bool preferredKeyFound = false;
if (offset + 1 > len) return 0;
int numKeySections = buf[offset]; offset++;
for (int i = 0; i < numKeySections; i++)
{
if (offset + 4 > len) return 0;
uint16_t keyType = bufbe16toh (buf + offset); offset += 2; // encryption key type
uint16_t encryptionKeyLen = bufbe16toh (buf + offset); offset += 2;
if (offset + encryptionKeyLen > len) return 0;
if (IsStoreLeases () && !preferredKeyFound) // create encryptor with leases only
{
// we pick first valid key if preferred not found
auto encryptor = i2p::data::IdentityEx::CreateEncryptor (keyType, buf + offset);
if (encryptor && (!m_Encryptor || keyType == preferredKeyType))
{
m_Encryptor = encryptor; // TODO: atomic
m_EncryptionType = keyType;
if (keyType == preferredKeyType) preferredKeyFound = true;
}
}
offset += encryptionKeyLen;
}
// leases
if (offset + 1 > len) return 0;
int numLeases = buf[offset]; offset++;
auto ts = i2p::util::GetMillisecondsSinceEpoch ();
if (IsStoreLeases ())
{
UpdateLeasesBegin ();
for (int i = 0; i < numLeases; i++)
{
if (offset + LEASE2_SIZE > len) return 0;
Lease lease;
lease.tunnelGateway = buf + offset; offset += 32; // gateway
lease.tunnelID = bufbe32toh (buf + offset); offset += 4; // tunnel ID
lease.endDate = bufbe32toh (buf + offset)*1000LL; offset += 4; // end date
UpdateLease (lease, ts);
}
UpdateLeasesEnd ();
}
else
offset += numLeases*LEASE2_SIZE; // 40 bytes per lease
return (offset > len ? 0 : offset);
}
size_t LeaseSet2::ReadMetaLS2TypeSpecificPart (const uint8_t * buf, size_t len)
{
size_t offset = 0;
// properties
uint16_t propertiesLen = bufbe16toh (buf + offset); offset += 2;
offset += propertiesLen; // skip for now. TODO: implement properties
// entries
if (offset + 1 > len) return 0;
int numEntries = buf[offset]; offset++;
for (int i = 0; i < numEntries; i++)
{
if (offset + LEASE2_SIZE > len) return 0;
offset += 32; // hash
offset += 3; // flags
offset += 1; // cost
offset += 4; // expires
}
// revocations
if (offset + 1 > len) return 0;
int numRevocations = buf[offset]; offset++;
for (int i = 0; i < numRevocations; i++)
{
if (offset + 32 > len) return 0;
offset += 32; // hash
}
return offset;
}
void LeaseSet2::ReadFromBufferEncrypted (const uint8_t * buf, size_t len, std::shared_ptr<const BlindedPublicKey> key, const uint8_t * secret)
{
size_t offset = 0;
// blinded key
if (len < 2) return;
const uint8_t * stA1 = buf + offset; // stA1 = blinded signature type, 2 bytes big endian
uint16_t blindedKeyType = bufbe16toh (stA1); offset += 2;
std::unique_ptr<i2p::crypto::Verifier> blindedVerifier (i2p::data::IdentityEx::CreateVerifier (blindedKeyType));
if (!blindedVerifier) return;
auto blindedKeyLen = blindedVerifier->GetPublicKeyLen ();
if (offset + blindedKeyLen >= len) return;
const uint8_t * blindedPublicKey = buf + offset;
blindedVerifier->SetPublicKey (blindedPublicKey); offset += blindedKeyLen;
// expiration
if (offset + 8 >= len) return;
const uint8_t * publishedTimestamp = buf + offset;
m_PublishedTimestamp = bufbe32toh (publishedTimestamp); offset += 4; // published timestamp (seconds)
uint16_t expires = bufbe16toh (buf + offset); offset += 2; // expires (seconds)
SetExpirationTime ((m_PublishedTimestamp + expires)*1000LL); // in milliseconds
uint16_t flags = bufbe16toh (buf + offset); offset += 2; // flags
if (flags & LEASESET2_FLAG_OFFLINE_KEYS)
{
// transient key
m_TransientVerifier = ProcessOfflineSignature (blindedVerifier, buf, len, offset);
if (!m_TransientVerifier)
{
LogPrint (eLogError, "LeaseSet2: Offline signature failed");
return;
}
}
// outer ciphertext
if (offset + 2 > len) return;
uint16_t lenOuterCiphertext = bufbe16toh (buf + offset); offset += 2;
const uint8_t * outerCiphertext = buf + offset;
offset += lenOuterCiphertext;
// verify signature
bool verified = m_TransientVerifier ? VerifySignature (m_TransientVerifier, buf, len, offset) :
VerifySignature (blindedVerifier, buf, len, offset);
SetIsValid (verified);
// handle ciphertext
if (verified && key && lenOuterCiphertext >= 32)
{
SetIsValid (false); // we must verify it again in Layer 2
if (blindedKeyType == key->GetBlindedSigType ())
{
// verify blinding
char date[9];
i2p::util::GetDateString (m_PublishedTimestamp, date);
std::vector<uint8_t> blinded (blindedKeyLen);
key->GetBlindedKey (date, blinded.data ());
if (memcmp (blindedPublicKey, blinded.data (), blindedKeyLen))
{
LogPrint (eLogError, "LeaseSet2: Blinded public key doesn't match");
return;
}
}
else
{
LogPrint (eLogError, "LeaseSet2: Unexpected blinded key type ", blindedKeyType, " instead ", key->GetBlindedSigType ());
return;
}
// outer key
// outerInput = subcredential || publishedTimestamp
uint8_t subcredential[36];
key->GetSubcredential (blindedPublicKey, blindedKeyLen, subcredential);
memcpy (subcredential + 32, publishedTimestamp, 4);
// outerSalt = outerCiphertext[0:32]
// keys = HKDF(outerSalt, outerInput, "ELS2_L1K", 44)
uint8_t keys[64]; // 44 bytes actual data
i2p::crypto::HKDF (outerCiphertext, subcredential, 36, "ELS2_L1K", keys);
// decrypt Layer 1
// outerKey = keys[0:31]
// outerIV = keys[32:43]
size_t lenOuterPlaintext = lenOuterCiphertext - 32;
std::vector<uint8_t> outerPlainText (lenOuterPlaintext);
i2p::crypto::ChaCha20 (outerCiphertext + 32, lenOuterPlaintext, keys, keys + 32, outerPlainText.data ());
// inner key
// innerInput = authCookie || subcredential || publishedTimestamp
// innerSalt = innerCiphertext[0:32]
// keys = HKDF(innerSalt, innerInput, "ELS2_L2K", 44)
uint8_t innerInput[68];
size_t authDataLen = ExtractClientAuthData (outerPlainText.data (), lenOuterPlaintext, secret, subcredential, innerInput);
if (authDataLen > 0)
{
memcpy (innerInput + 32, subcredential, 36);
i2p::crypto::HKDF (outerPlainText.data () + 1 + authDataLen, innerInput, 68, "ELS2_L2K", keys);
}
else
// no authData presented, innerInput = subcredential || publishedTimestamp
// skip 1 byte flags
i2p::crypto::HKDF (outerPlainText.data () + 1, subcredential, 36, "ELS2_L2K", keys); // no authCookie
// decrypt Layer 2
// innerKey = keys[0:31]
// innerIV = keys[32:43]
size_t lenInnerPlaintext = lenOuterPlaintext - 32 - 1 - authDataLen;
std::vector<uint8_t> innerPlainText (lenInnerPlaintext);
i2p::crypto::ChaCha20 (outerPlainText.data () + 32 + 1 + authDataLen, lenInnerPlaintext, keys, keys + 32, innerPlainText.data ());
if (innerPlainText[0] == NETDB_STORE_TYPE_STANDARD_LEASESET2 || innerPlainText[0] == NETDB_STORE_TYPE_META_LEASESET2)
{
// override store type and buffer
m_StoreType = innerPlainText[0];
SetBuffer (innerPlainText.data () + 1, lenInnerPlaintext - 1);
// parse and verify Layer 2
ReadFromBuffer (innerPlainText.data () + 1, lenInnerPlaintext - 1);
}
else
LogPrint (eLogError, "LeaseSet2: Unexpected LeaseSet type ", (int)innerPlainText[0], " inside encrypted LeaseSet");
}
else
{
// we set actual length of encrypted buffer
offset += m_TransientVerifier ? m_TransientVerifier->GetSignatureLen () : blindedVerifier->GetSignatureLen ();
SetBufferLen (offset);
}
}
// helper for ExtractClientAuthData
static inline bool GetAuthCookie (const uint8_t * authClients, int numClients, const uint8_t * okm, uint8_t * authCookie)
{
// try to find clientCookie_i for clientID_i = okm[44:51]
for (int i = 0; i < numClients; i++)
{
if (!memcmp (okm + 44, authClients + i*40, 8)) // clientID_i
{
// clientKey_i = okm[0:31]
// clientIV_i = okm[32:43]
i2p::crypto::ChaCha20 (authClients + i*40 + 8, 32, okm, okm + 32, authCookie); // clientCookie_i
return true;
}
}
return false;
}
size_t LeaseSet2::ExtractClientAuthData (const uint8_t * buf, size_t len, const uint8_t * secret, const uint8_t * subcredential, uint8_t * authCookie) const
{
size_t offset = 0;
uint8_t flag = buf[offset]; offset++; // flag
if (flag & 0x01) // client auth
{
if (!(flag & 0x0E)) // DH, bit 1-3 all zeroes
{
const uint8_t * ephemeralPublicKey = buf + offset; offset += 32; // ephemeralPublicKey
uint16_t numClients = bufbe16toh (buf + offset); offset += 2; // clients
const uint8_t * authClients = buf + offset; offset += numClients*40; // authClients
if (offset > len)
{
LogPrint (eLogError, "LeaseSet2: Too many clients ", numClients, " in DH auth data");
return 0;
}
// calculate authCookie
if (secret)
{
i2p::crypto::X25519Keys ck (secret, nullptr); // derive cpk_i from csk_i
uint8_t authInput[100];
ck.Agree (ephemeralPublicKey, authInput); // sharedSecret is first 32 bytes of authInput
memcpy (authInput + 32, ck.GetPublicKey (), 32); // cpk_i
memcpy (authInput + 64, subcredential, 36);
uint8_t okm[64]; // 52 actual data
i2p::crypto::HKDF (ephemeralPublicKey, authInput, 100, "ELS2_XCA", okm);
if (!GetAuthCookie (authClients, numClients, okm, authCookie))
LogPrint (eLogError, "LeaseSet2: Client cookie DH not found");
}
else
LogPrint (eLogError, "LeaseSet2: Can't calculate authCookie: csk_i is not provided");
}
else if (flag & 0x02) // PSK, bit 1 is set to 1
{
const uint8_t * authSalt = buf + offset; offset += 32; // authSalt
uint16_t numClients = bufbe16toh (buf + offset); offset += 2; // clients
const uint8_t * authClients = buf + offset; offset += numClients*40; // authClients
if (offset > len)
{
LogPrint (eLogError, "LeaseSet2: Too many clients ", numClients, " in PSK auth data");
return 0;
}
// calculate authCookie
if (secret)
{
uint8_t authInput[68];
memcpy (authInput, secret, 32);
memcpy (authInput + 32, subcredential, 36);
uint8_t okm[64]; // 52 actual data
i2p::crypto::HKDF (authSalt, authInput, 68, "ELS2PSKA", okm);
if (!GetAuthCookie (authClients, numClients, okm, authCookie))
LogPrint (eLogError, "LeaseSet2: Client cookie PSK not found");
}
else
LogPrint (eLogError, "LeaseSet2: Can't calculate authCookie: psk_i is not provided");
}
else
LogPrint (eLogError, "LeaseSet2: Unknown client auth type ", (int)flag);
}
return offset - 1;
}
void LeaseSet2::Encrypt (const uint8_t * data, uint8_t * encrypted) const
{
auto encryptor = m_Encryptor; // TODO: atomic
if (encryptor)
encryptor->Encrypt (data, encrypted);
}
uint64_t LeaseSet2::ExtractExpirationTimestamp (const uint8_t * buf, size_t len) const
{
uint64_t expiration = 0;
ExtractPublishedTimestamp (buf, len, expiration);
return expiration;
}
uint64_t LeaseSet2::ExtractPublishedTimestamp (const uint8_t * buf, size_t len, uint64_t& expiration) const
{
if (len < 8) return 0;
if (m_StoreType == NETDB_STORE_TYPE_ENCRYPTED_LEASESET2)
{
// encrypted LS2
size_t offset = 0;
uint16_t blindedKeyType = bufbe16toh (buf + offset); offset += 2;
std::unique_ptr<i2p::crypto::Verifier> blindedVerifier (i2p::data::IdentityEx::CreateVerifier (blindedKeyType));
if (!blindedVerifier) return 0 ;
auto blindedKeyLen = blindedVerifier->GetPublicKeyLen ();
if (offset + blindedKeyLen + 6 >= len) return 0;
offset += blindedKeyLen;
uint32_t timestamp = bufbe32toh (buf + offset); offset += 4;
uint16_t expires = bufbe16toh (buf + offset); offset += 2;
expiration = (timestamp + expires)* 1000LL;
return timestamp;
}
else
{
auto identity = GetIdentity ();
if (!identity) return 0;
size_t offset = identity->GetFullLen ();
if (offset + 6 >= len) return 0;
uint32_t timestamp = bufbe32toh (buf + offset); offset += 4;
uint16_t expires = bufbe16toh (buf + offset); offset += 2;
expiration = (timestamp + expires)* 1000LL;
return timestamp;
}
}
LocalLeaseSet::LocalLeaseSet (std::shared_ptr<const IdentityEx> identity, const uint8_t * encryptionPublicKey, std::vector<std::shared_ptr<i2p::tunnel::InboundTunnel> > tunnels):
m_ExpirationTime (0), m_Identity (identity)
{
int num = tunnels.size ();
if (num > MAX_NUM_LEASES) num = MAX_NUM_LEASES;
// identity
auto signingKeyLen = m_Identity->GetSigningPublicKeyLen ();
m_BufferLen = m_Identity->GetFullLen () + 256 + signingKeyLen + 1 + num*LEASE_SIZE + m_Identity->GetSignatureLen ();
m_Buffer = new uint8_t[m_BufferLen];
auto offset = m_Identity->ToBuffer (m_Buffer, m_BufferLen);
memcpy (m_Buffer + offset, encryptionPublicKey, 256);
offset += 256;
memset (m_Buffer + offset, 0, signingKeyLen);
offset += signingKeyLen;
// num leases
m_Buffer[offset] = num;
offset++;
// leases
m_Leases = m_Buffer + offset;
auto currentTime = i2p::util::GetMillisecondsSinceEpoch ();
for (int i = 0; i < num; i++)
{
memcpy (m_Buffer + offset, tunnels[i]->GetNextIdentHash (), 32);
offset += 32; // gateway id
htobe32buf (m_Buffer + offset, tunnels[i]->GetNextTunnelID ());
offset += 4; // tunnel id
uint64_t ts = tunnels[i]->GetCreationTime () + i2p::tunnel::TUNNEL_EXPIRATION_TIMEOUT - i2p::tunnel::TUNNEL_EXPIRATION_THRESHOLD; // 1 minute before expiration
ts *= 1000; // in milliseconds
if (ts > m_ExpirationTime) m_ExpirationTime = ts;
// make sure leaseset is newer than previous, but adding some time to expiration date
ts += (currentTime - tunnels[i]->GetCreationTime ()*1000LL)*2/i2p::tunnel::TUNNEL_EXPIRATION_TIMEOUT; // up to 2 secs
htobe64buf (m_Buffer + offset, ts);
offset += 8; // end date
}
// we don't sign it yet. must be signed later on
}
LocalLeaseSet::LocalLeaseSet (std::shared_ptr<const IdentityEx> identity, const uint8_t * buf, size_t len):
m_ExpirationTime (0), m_Identity (identity)
{
if (buf)
{
m_BufferLen = len;
m_Buffer = new uint8_t[m_BufferLen];
memcpy (m_Buffer, buf, len);
}
else
{
m_Buffer = nullptr;
m_BufferLen = 0;
}
}
bool LocalLeaseSet::IsExpired () const
{
auto ts = i2p::util::GetMillisecondsSinceEpoch ();
return ts > m_ExpirationTime;
}
bool LeaseSetBufferValidate(const uint8_t * ptr, size_t sz, uint64_t & expires)
{
IdentityEx ident(ptr, sz);
size_t size = ident.GetFullLen ();
if (size > sz)
{
LogPrint (eLogError, "LeaseSet: Identity length ", size, " exceeds buffer size ", sz);
return false;
}
// encryption key
size += 256;
// signing key (unused)
size += ident.GetSigningPublicKeyLen ();
uint8_t numLeases = ptr[size];
++size;
if (!numLeases || numLeases > MAX_NUM_LEASES)
{
LogPrint (eLogError, "LeaseSet: Incorrect number of leases", (int)numLeases);
return false;
}
const uint8_t * leases = ptr + size;
expires = 0;
/** find lease with the max expiration timestamp */
for (int i = 0; i < numLeases; i++)
{
leases += 36; // gateway + tunnel ID
uint64_t endDate = bufbe64toh (leases);
leases += 8; // end date
if(endDate > expires)
expires = endDate;
}
return ident.Verify(ptr, leases - ptr, leases);
}
LocalLeaseSet2::LocalLeaseSet2 (uint8_t storeType, const i2p::data::PrivateKeys& keys,
const KeySections& encryptionKeys, const std::vector<std::shared_ptr<i2p::tunnel::InboundTunnel> >& tunnels,
bool isPublic, bool isPublishedEncrypted):
LocalLeaseSet (keys.GetPublic (), nullptr, 0)
{
auto identity = keys.GetPublic ();
// assume standard LS2
int num = tunnels.size ();
if (num > MAX_NUM_LEASES) num = MAX_NUM_LEASES;
size_t keySectionsLen = 0;
for (const auto& it: encryptionKeys)
keySectionsLen += 2/*key type*/ + 2/*key len*/ + it.keyLen/*key*/;
m_BufferLen = identity->GetFullLen () + 4/*published*/ + 2/*expires*/ + 2/*flag*/ + 2/*properties len*/ +
1/*num keys*/ + keySectionsLen + 1/*num leases*/ + num*LEASE2_SIZE + keys.GetSignatureLen ();
uint16_t flags = 0;
if (keys.IsOfflineSignature ())
{
flags |= LEASESET2_FLAG_OFFLINE_KEYS;
m_BufferLen += keys.GetOfflineSignature ().size ();
}
if (isPublishedEncrypted)
{
flags |= LEASESET2_FLAG_PUBLISHED_ENCRYPTED;
isPublic = true;
}
if (!isPublic) flags |= LEASESET2_FLAG_UNPUBLISHED_LEASESET;
m_Buffer = new uint8_t[m_BufferLen + 1];
m_Buffer[0] = storeType;
// LS2 header
auto offset = identity->ToBuffer (m_Buffer + 1, m_BufferLen) + 1;
auto timestamp = i2p::util::GetSecondsSinceEpoch ();
htobe32buf (m_Buffer + offset, timestamp); offset += 4; // published timestamp (seconds)
uint8_t * expiresBuf = m_Buffer + offset; offset += 2; // expires, fill later
htobe16buf (m_Buffer + offset, flags); offset += 2; // flags
if (keys.IsOfflineSignature ())
{
// offline signature
const auto& offlineSignature = keys.GetOfflineSignature ();
memcpy (m_Buffer + offset, offlineSignature.data (), offlineSignature.size ());
offset += offlineSignature.size ();
}
htobe16buf (m_Buffer + offset, 0); offset += 2; // properties len
// keys
m_Buffer[offset] = encryptionKeys.size (); offset++; // 1 key
for (const auto& it: encryptionKeys)
{
htobe16buf (m_Buffer + offset, it.keyType); offset += 2; // key type
htobe16buf (m_Buffer + offset, it.keyLen); offset += 2; // key len
memcpy (m_Buffer + offset, it.encryptionPublicKey, it.keyLen); offset += it.keyLen; // key
}
// leases
uint32_t expirationTime = 0; // in seconds
m_Buffer[offset] = num; offset++; // num leases
for (int i = 0; i < num; i++)
{
memcpy (m_Buffer + offset, tunnels[i]->GetNextIdentHash (), 32);
offset += 32; // gateway id
htobe32buf (m_Buffer + offset, tunnels[i]->GetNextTunnelID ());
offset += 4; // tunnel id
auto ts = tunnels[i]->GetCreationTime () + i2p::tunnel::TUNNEL_EXPIRATION_TIMEOUT - i2p::tunnel::TUNNEL_EXPIRATION_THRESHOLD; // in seconds, 1 minute before expiration
if (ts > expirationTime) expirationTime = ts;
htobe32buf (m_Buffer + offset, ts);
offset += 4; // end date
}
// update expiration
if (expirationTime)
{
SetExpirationTime (expirationTime*1000LL);
auto expires = (int)expirationTime - timestamp;
htobe16buf (expiresBuf, expires > 0 ? expires : 0);
}
else
{
// no tunnels or withdraw
SetExpirationTime (timestamp*1000LL);
memset (expiresBuf, 0, 2); // expires immeditely
}
// sign
keys.Sign (m_Buffer, offset, m_Buffer + offset); // LS + leading store type
}
LocalLeaseSet2::LocalLeaseSet2 (uint8_t storeType, std::shared_ptr<const IdentityEx> identity, const uint8_t * buf, size_t len):
LocalLeaseSet (identity, nullptr, 0)
{
m_BufferLen = len;
m_Buffer = new uint8_t[m_BufferLen + 1];
memcpy (m_Buffer + 1, buf, len);
m_Buffer[0] = storeType;
}
LocalEncryptedLeaseSet2::LocalEncryptedLeaseSet2 (std::shared_ptr<const LocalLeaseSet2> ls, const i2p::data::PrivateKeys& keys,
int authType, std::shared_ptr<std::vector<AuthPublicKey> > authKeys):
LocalLeaseSet2 (ls->GetIdentity ()), m_InnerLeaseSet (ls)
{
size_t lenInnerPlaintext = ls->GetBufferLen () + 1, lenOuterPlaintext = lenInnerPlaintext + 32 + 1;
uint8_t layer1Flags = 0;
if (authKeys)
{
if (authType == ENCRYPTED_LEASESET_AUTH_TYPE_DH) layer1Flags |= 0x01; // DH, authentication scheme 0, auth bit 1
else if (authType == ENCRYPTED_LEASESET_AUTH_TYPE_PSK) layer1Flags |= 0x03; // PSK, authentication scheme 1, auth bit 1
if (layer1Flags)
lenOuterPlaintext += 32 + 2 + authKeys->size ()*40; // auth data len
}
size_t lenOuterCiphertext = lenOuterPlaintext + 32;
m_BufferLen = 2/*blinded sig type*/ + 32/*blinded pub key*/ + 4/*published*/ + 2/*expires*/ + 2/*flags*/ + 2/*lenOuterCiphertext*/ + lenOuterCiphertext + 64/*signature*/;
m_Buffer = new uint8_t[m_BufferLen + 1];
m_Buffer[0] = NETDB_STORE_TYPE_ENCRYPTED_LEASESET2;
BlindedPublicKey blindedKey (ls->GetIdentity ());
auto timestamp = i2p::util::GetSecondsSinceEpoch ();
char date[9];
i2p::util::GetDateString (timestamp, date);
uint8_t blindedPriv[64], blindedPub[128]; // 64 and 128 max
size_t publicKeyLen = blindedKey.BlindPrivateKey (keys.GetSigningPrivateKey (), date, blindedPriv, blindedPub);
std::unique_ptr<i2p::crypto::Signer> blindedSigner (i2p::data::PrivateKeys::CreateSigner (blindedKey.GetBlindedSigType (), blindedPriv));
if (!blindedSigner)
{
LogPrint (eLogError, "LeaseSet2: Can't create blinded signer for signature type ", blindedKey.GetSigType ());
return;
}
auto offset = 1;
htobe16buf (m_Buffer + offset, blindedKey.GetBlindedSigType ()); offset += 2; // Blinded Public Key Sig Type
memcpy (m_Buffer + offset, blindedPub, publicKeyLen); offset += publicKeyLen; // Blinded Public Key
htobe32buf (m_Buffer + offset, timestamp); offset += 4; // published timestamp (seconds)
auto nextMidnight = (timestamp/86400LL + 1)*86400LL; // 86400 = 24*3600 seconds
auto expirationTime = ls->GetExpirationTime ()/1000LL;
if (expirationTime > nextMidnight) expirationTime = nextMidnight;
SetExpirationTime (expirationTime*1000LL);
htobe16buf (m_Buffer + offset, expirationTime > timestamp ? expirationTime - timestamp : 0); offset += 2; // expires
uint16_t flags = 0;
htobe16buf (m_Buffer + offset, flags); offset += 2; // flags
htobe16buf (m_Buffer + offset, lenOuterCiphertext); offset += 2; // lenOuterCiphertext
// outerChipherText
// Layer 1
uint8_t subcredential[36];
blindedKey.GetSubcredential (blindedPub, 32, subcredential);
htobe32buf (subcredential + 32, timestamp); // outerInput = subcredential || publishedTimestamp
// keys = HKDF(outerSalt, outerInput, "ELS2_L1K", 44)
uint8_t keys1[64]; // 44 bytes actual data
RAND_bytes (m_Buffer + offset, 32); // outerSalt = CSRNG(32)
i2p::crypto::HKDF (m_Buffer + offset, subcredential, 36, "ELS2_L1K", keys1);
offset += 32; // outerSalt
uint8_t * outerPlainText = m_Buffer + offset;
m_Buffer[offset] = layer1Flags; offset++; // layer 1 flags
// auth data
uint8_t innerInput[68]; // authCookie || subcredential || publishedTimestamp
if (layer1Flags)
{
RAND_bytes (innerInput, 32); // authCookie
CreateClientAuthData (subcredential, authType, authKeys, innerInput, m_Buffer + offset);
offset += 32 + 2 + authKeys->size ()*40; // auth clients
}
// Layer 2
// keys = HKDF(outerSalt, outerInput, "ELS2_L2K", 44)
uint8_t keys2[64]; // 44 bytes actual data
RAND_bytes (m_Buffer + offset, 32); // innerSalt = CSRNG(32)
if (layer1Flags)
{
memcpy (innerInput + 32, subcredential, 36); // + subcredential || publishedTimestamp
i2p::crypto::HKDF (m_Buffer + offset, innerInput, 68, "ELS2_L2K", keys2);
}
else
i2p::crypto::HKDF (m_Buffer + offset, subcredential, 36, "ELS2_L2K", keys2); // no authCookie
offset += 32; // innerSalt
m_Buffer[offset] = ls->GetStoreType ();
memcpy (m_Buffer + offset + 1, ls->GetBuffer (), ls->GetBufferLen ());
i2p::crypto::ChaCha20 (m_Buffer + offset, lenInnerPlaintext, keys2, keys2 + 32, m_Buffer + offset); // encrypt Layer 2
offset += lenInnerPlaintext;
i2p::crypto::ChaCha20 (outerPlainText, lenOuterPlaintext, keys1, keys1 + 32, outerPlainText); // encrypt Layer 1
// signature
blindedSigner->Sign (m_Buffer, offset, m_Buffer + offset);
// store hash
m_StoreHash = blindedKey.GetStoreHash (date);
}
LocalEncryptedLeaseSet2::LocalEncryptedLeaseSet2 (std::shared_ptr<const IdentityEx> identity, const uint8_t * buf, size_t len):
LocalLeaseSet2 (NETDB_STORE_TYPE_ENCRYPTED_LEASESET2, identity, buf, len)
{
// fill inner LeaseSet2
auto blindedKey = std::make_shared<BlindedPublicKey>(identity);
i2p::data::LeaseSet2 ls (buf, len, blindedKey); // inner layer
if (ls.IsValid ())
{
m_InnerLeaseSet = std::make_shared<LocalLeaseSet2>(ls.GetStoreType (), identity, ls.GetBuffer (), ls.GetBufferLen ());
m_StoreHash = blindedKey->GetStoreHash ();
}
else
LogPrint (eLogError, "LeaseSet2: Couldn't extract inner layer");
}
void LocalEncryptedLeaseSet2::CreateClientAuthData (const uint8_t * subcredential, int authType, std::shared_ptr<std::vector<AuthPublicKey> > authKeys, const uint8_t * authCookie, uint8_t * authData) const
{
if (authType == ENCRYPTED_LEASESET_AUTH_TYPE_DH)
{
i2p::crypto::X25519Keys ek;
ek.GenerateKeys (); // esk and epk
memcpy (authData, ek.GetPublicKey (), 32); authData += 32; // epk
htobe16buf (authData, authKeys->size ()); authData += 2; // num clients
uint8_t authInput[100]; // sharedSecret || cpk_i || subcredential || publishedTimestamp
memcpy (authInput + 64, subcredential, 36);
for (auto& it: *authKeys)
{
ek.Agree (it, authInput); // sharedSecret = DH(esk, cpk_i)
memcpy (authInput + 32, it, 32);
uint8_t okm[64]; // 52 actual data
i2p::crypto::HKDF (ek.GetPublicKey (), authInput, 100, "ELS2_XCA", okm);
memcpy (authData, okm + 44, 8); authData += 8; // clientID_i
i2p::crypto::ChaCha20 (authCookie, 32, okm, okm + 32, authData); authData += 32; // clientCookie_i
}
}
else // assume PSK
{
uint8_t authSalt[32];
RAND_bytes (authSalt, 32);
memcpy (authData, authSalt, 32); authData += 32; // authSalt
htobe16buf (authData, authKeys->size ()); authData += 2; // num clients
uint8_t authInput[68]; // authInput = psk_i || subcredential || publishedTimestamp
memcpy (authInput + 32, subcredential, 36);
for (auto& it: *authKeys)
{
memcpy (authInput, it, 32);
uint8_t okm[64]; // 52 actual data
i2p::crypto::HKDF (authSalt, authInput, 68, "ELS2PSKA", okm);
memcpy (authData, okm + 44, 8); authData += 8; // clientID_i
i2p::crypto::ChaCha20 (authCookie, 32, okm, okm + 32, authData); authData += 32; // clientCookie_i
}
}
}
}
}