diff --git a/src/cryptonote_core/cryptonote_core.cpp b/src/cryptonote_core/cryptonote_core.cpp index f918afa33..2f55cc40b 100644 --- a/src/cryptonote_core/cryptonote_core.cpp +++ b/src/cryptonote_core/cryptonote_core.cpp @@ -160,6 +160,11 @@ namespace cryptonote , "Relay blocks as normal blocks" , false }; + static const command_line::arg_descriptor arg_pad_transactions = { + "pad-transactions" + , "Pad relayed transactions to help defend against traffic volume analysis" + , false + }; static const command_line::arg_descriptor arg_max_txpool_weight = { "max-txpool-weight" , "Set maximum txpool weight in bytes." @@ -185,7 +190,8 @@ namespace cryptonote m_disable_dns_checkpoints(false), m_update_download(0), m_nettype(UNDEFINED), - m_update_available(false) + m_update_available(false), + m_pad_transactions(false) { m_checkpoints_updating.clear(); set_cryptonote_protocol(pprotocol); @@ -279,6 +285,7 @@ namespace cryptonote command_line::add_arg(desc, arg_offline); command_line::add_arg(desc, arg_disable_dns_checkpoints); command_line::add_arg(desc, arg_max_txpool_weight); + command_line::add_arg(desc, arg_pad_transactions); command_line::add_arg(desc, arg_block_notify); miner::init_options(desc); @@ -317,6 +324,7 @@ namespace cryptonote set_enforce_dns_checkpoints(command_line::get_arg(vm, arg_dns_checkpoints)); test_drop_download_height(command_line::get_arg(vm, arg_test_drop_download_height)); m_fluffy_blocks_enabled = !get_arg(vm, arg_no_fluffy_blocks); + m_pad_transactions = get_arg(vm, arg_pad_transactions); m_offline = get_arg(vm, arg_offline); m_disable_dns_checkpoints = get_arg(vm, arg_disable_dns_checkpoints); if (!command_line::is_arg_defaulted(vm, arg_fluffy_blocks)) diff --git a/src/cryptonote_core/cryptonote_core.h b/src/cryptonote_core/cryptonote_core.h index 0ae063342..cc53fce58 100644 --- a/src/cryptonote_core/cryptonote_core.h +++ b/src/cryptonote_core/cryptonote_core.h @@ -754,6 +754,13 @@ namespace cryptonote */ bool fluffy_blocks_enabled() const { return m_fluffy_blocks_enabled; } + /** + * @brief get whether transaction relay should be padded + * + * @return whether transaction relay should be padded + */ + bool pad_transactions() const { return m_pad_transactions; } + /** * @brief check a set of hashes against the precompiled hash set * @@ -1013,6 +1020,7 @@ namespace cryptonote bool m_fluffy_blocks_enabled; bool m_offline; + bool m_pad_transactions; }; } diff --git a/src/cryptonote_protocol/cryptonote_protocol_defs.h b/src/cryptonote_protocol/cryptonote_protocol_defs.h index db159f0f4..d5bb50930 100644 --- a/src/cryptonote_protocol/cryptonote_protocol_defs.h +++ b/src/cryptonote_protocol/cryptonote_protocol_defs.h @@ -146,9 +146,11 @@ namespace cryptonote struct request { std::vector txs; + std::string _; // padding BEGIN_KV_SERIALIZE_MAP() KV_SERIALIZE(txs) + KV_SERIALIZE(_) END_KV_SERIALIZE_MAP() }; }; diff --git a/src/cryptonote_protocol/cryptonote_protocol_handler.inl b/src/cryptonote_protocol/cryptonote_protocol_handler.inl index 5ba637c2f..1de0cde07 100644 --- a/src/cryptonote_protocol/cryptonote_protocol_handler.inl +++ b/src/cryptonote_protocol/cryptonote_protocol_handler.inl @@ -1726,8 +1726,39 @@ skip: bool t_cryptonote_protocol_handler::relay_transactions(NOTIFY_NEW_TRANSACTIONS::request& arg, cryptonote_connection_context& exclude_context) { // no check for success, so tell core they're relayed unconditionally + const bool pad_transactions = m_core.pad_transactions(); + size_t bytes = pad_transactions ? 9 /* header */ + 4 /* 1 + 'txs' */ + tools::get_varint_data(arg.txs.size()).size() : 0; for(auto tx_blob_it = arg.txs.begin(); tx_blob_it!=arg.txs.end(); ++tx_blob_it) + { m_core.on_transaction_relayed(*tx_blob_it); + if (pad_transactions) + bytes += tools::get_varint_data(tx_blob_it->size()).size() + tx_blob_it->size(); + } + + if (pad_transactions) + { + // stuff some dummy bytes in to stay safe from traffic volume analysis + static constexpr size_t granularity = 1024; + size_t padding = granularity - bytes % granularity; + const size_t overhead = 2 /* 1 + '_' */ + tools::get_varint_data(padding).size(); + if (overhead > padding) + padding = 0; + else + padding -= overhead; + arg._ = std::string(padding, ' '); + + std::string arg_buff; + epee::serialization::store_t_to_binary(arg, arg_buff); + + // we probably lowballed the payload size a bit, so added a but too much. Fix this now. + size_t remove = arg_buff.size() % granularity; + if (remove > arg._.size()) + arg._.clear(); + else + arg._.resize(arg._.size() - remove); + // if the size of _ moved enough, we might lose byte in size encoding, we don't care + } + return relay_post_notify(arg, exclude_context); } //------------------------------------------------------------------------------------------------------------------------ diff --git a/tests/core_proxy/core_proxy.h b/tests/core_proxy/core_proxy.h index 7d36a0f68..023c220ae 100644 --- a/tests/core_proxy/core_proxy.h +++ b/tests/core_proxy/core_proxy.h @@ -104,5 +104,6 @@ namespace tests cryptonote::difficulty_type get_block_cumulative_difficulty(uint64_t height) const { return 0; } bool fluffy_blocks_enabled() const { return false; } uint64_t prevalidate_block_hashes(uint64_t height, const std::vector &hashes) { return 0; } + bool pad_transactions() const { return false; } }; } diff --git a/tests/unit_tests/ban.cpp b/tests/unit_tests/ban.cpp index e3dbdaef1..12625a949 100644 --- a/tests/unit_tests/ban.cpp +++ b/tests/unit_tests/ban.cpp @@ -83,6 +83,7 @@ public: cryptonote::difficulty_type get_block_cumulative_difficulty(uint64_t height) const { return 0; } bool fluffy_blocks_enabled() const { return false; } uint64_t prevalidate_block_hashes(uint64_t height, const std::vector &hashes) { return 0; } + bool pad_transactions() { return false; } void stop() {} };