From ea87b30f8907ee11252433811e7a7d0c46758cca Mon Sep 17 00:00:00 2001 From: j-berman Date: Mon, 15 Nov 2021 05:23:53 -0800 Subject: Add view tags to outputs to reduce wallet scanning time Implements view tags as proposed by @UkoeHB in MRL issue https://github.com/monero-project/research-lab/issues/73 At tx construction, the sender adds a 1-byte view tag to each output. The view tag is derived from the sender-receiver shared secret. When scanning for outputs, the receiver can check the view tag for a match, in order to reduce scanning time. When the view tag does not match, the wallet avoids the more expensive EC operations when deriving the output public key using the shared secret. --- src/device/device_default.cpp | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) (limited to 'src/device/device_default.cpp') diff --git a/src/device/device_default.cpp b/src/device/device_default.cpp index e7b452d40..d70ece229 100644 --- a/src/device/device_default.cpp +++ b/src/device/device_default.cpp @@ -263,6 +263,11 @@ namespace hw { return true; } + bool device_default::derive_view_tag(const crypto::key_derivation &derivation, const std::size_t output_index, crypto::view_tag &view_tag) { + crypto::derive_view_tag(derivation, output_index, view_tag); + return true; + } + bool device_default::conceal_derivation(crypto::key_derivation &derivation, const crypto::public_key &tx_pub_key, const std::vector &additional_tx_pub_keys, const crypto::key_derivation &main_derivation, const std::vector &additional_derivations){ return true; } @@ -291,7 +296,8 @@ namespace hw { const cryptonote::tx_destination_entry &dst_entr, const boost::optional &change_addr, const size_t output_index, const bool &need_additional_txkeys, const std::vector &additional_tx_keys, std::vector &additional_tx_public_keys, - std::vector &amount_keys, crypto::public_key &out_eph_public_key) { + std::vector &amount_keys, crypto::public_key &out_eph_public_key, + const bool use_view_tags, crypto::view_tag &view_tag) { crypto::key_derivation derivation; @@ -331,6 +337,12 @@ namespace hw { derivation_to_scalar(derivation, output_index, scalar1); amount_keys.push_back(rct::sk2rct(scalar1)); } + + if (use_view_tags) + { + derive_view_tag(derivation, output_index, view_tag); + } + r = derive_public_key(derivation, output_index, dst_entr.addr.m_spend_public_key, out_eph_public_key); CHECK_AND_ASSERT_MES(r, false, "at creation outs: failed to derive_public_key(" << derivation << ", " << output_index << ", "<< dst_entr.addr.m_spend_public_key << ")"); -- cgit v1.2.3