Spend proof without txkey

1 files changed, 230 insertions, 0 deletions

diff --git a/src/wallet/wallet2.cpp b/src/wallet/wallet2.cpp
index c4124a677..bfbb653a3 100644
--- a/src/wallet/wallet2.cpp
+++ b/src/wallet/wallet2.cpp
@@ -6209,6 +6209,236 @@ bool wallet2::get_tx_key(const crypto::hash &txid, crypto::secret_key &tx_key, s
     additional_tx_keys = j->second;
   return true;
 }
+//----------------------------------------------------------------------------------------------------
+std::string wallet2::get_spend_proof(const crypto::hash &txid, const std::string &message)
+{
+  THROW_WALLET_EXCEPTION_IF(m_watch_only, error::wallet_internal_error,
+    "get_spend_proof requires spend secret key and is not available for a watch-only wallet");
+
+  // fetch tx from daemon
+  COMMAND_RPC_GET_TRANSACTIONS::request req = AUTO_VAL_INIT(req);
+  req.txs_hashes.push_back(epee::string_tools::pod_to_hex(txid));
+  req.decode_as_json = false;
+  COMMAND_RPC_GET_TRANSACTIONS::response res = AUTO_VAL_INIT(res);
+  bool r;
+  {
+    const boost::lock_guard<boost::mutex> lock{m_daemon_rpc_mutex};
+    r = epee::net_utils::invoke_http_json("/gettransactions", req, res, m_http_client, rpc_timeout);
+  }
+  THROW_WALLET_EXCEPTION_IF(!r, error::no_connection_to_daemon, "gettransactions");
+  THROW_WALLET_EXCEPTION_IF(res.status == CORE_RPC_STATUS_BUSY, error::daemon_busy, "gettransactions");
+  THROW_WALLET_EXCEPTION_IF(res.status != CORE_RPC_STATUS_OK, error::wallet_internal_error, "gettransactions");
+  THROW_WALLET_EXCEPTION_IF(res.txs.size() != 1, error::wallet_internal_error,
+    "daemon returned wrong response for gettransactions, wrong txs count = " +
+    std::to_string(res.txs.size()) + ", expected 1");
+  cryptonote::blobdata bd;
+  THROW_WALLET_EXCEPTION_IF(!epee::string_tools::parse_hexstr_to_binbuff(res.txs[0].as_hex, bd), error::wallet_internal_error, "failed to parse tx from hexstr");
+  cryptonote::transaction tx;
+  crypto::hash tx_hash, tx_prefix_hash;
+  THROW_WALLET_EXCEPTION_IF(!cryptonote::parse_and_validate_tx_from_blob(bd, tx, tx_hash, tx_prefix_hash), error::wallet_internal_error, "failed to parse tx from blob");
+  THROW_WALLET_EXCEPTION_IF(tx_hash != txid, error::wallet_internal_error, "txid mismatch");
+
+  std::vector<std::vector<crypto::signature>> signatures;
+
+  // get signature prefix hash
+  std::string sig_prefix_data((const char*)&txid, sizeof(crypto::hash));
+  sig_prefix_data += message;
+  crypto::hash sig_prefix_hash;
+  crypto::cn_fast_hash(sig_prefix_data.data(), sig_prefix_data.size(), sig_prefix_hash);
+
+  for(size_t i = 0; i < tx.vin.size(); ++i)
+  {
+    const txin_to_key* const in_key = boost::get<txin_to_key>(std::addressof(tx.vin[i]));
+    if (in_key == nullptr)
+      continue;
+
+    // check if the key image belongs to us
+    const auto found = m_key_images.find(in_key->k_image);
+    if(found == m_key_images.end())
+    {
+      THROW_WALLET_EXCEPTION_IF(i > 0, error::wallet_internal_error, "subset of key images belong to us, very weird!");
+      THROW_WALLET_EXCEPTION_IF(true, error::wallet_internal_error, "This tx wasn't generated by this wallet!");
+    }
+
+    // derive the real output keypair
+    const transfer_details& in_td = m_transfers[found->second];
+    const txout_to_key* const in_tx_out_pkey = boost::get<txout_to_key>(std::addressof(in_td.m_tx.vout[in_td.m_internal_output_index].target));
+    THROW_WALLET_EXCEPTION_IF(in_tx_out_pkey == nullptr, error::wallet_internal_error, "Output is not txout_to_key");
+    const crypto::public_key in_tx_pub_key = get_tx_pub_key_from_extra(in_td.m_tx, in_td.m_pk_index);
+    const std::vector<crypto::public_key> in_additionakl_tx_pub_keys = get_additional_tx_pub_keys_from_extra(in_td.m_tx);
+    keypair in_ephemeral;
+    crypto::key_image in_img;
+    THROW_WALLET_EXCEPTION_IF(!generate_key_image_helper(m_account.get_keys(), m_subaddresses, in_tx_out_pkey->key, in_tx_pub_key, in_additionakl_tx_pub_keys, in_td.m_internal_output_index, in_ephemeral, in_img),
+      error::wallet_internal_error, "failed to generate key image");
+    THROW_WALLET_EXCEPTION_IF(in_key->k_image != in_img, error::wallet_internal_error, "key image mismatch");
+
+    // get output pubkeys in the ring
+    const std::vector<uint64_t> absolute_offsets = cryptonote::relative_output_offsets_to_absolute(in_key->key_offsets);
+    const size_t ring_size = in_key->key_offsets.size();
+    THROW_WALLET_EXCEPTION_IF(absolute_offsets.size() != ring_size, error::wallet_internal_error, "absolute offsets size is wrong");
+    COMMAND_RPC_GET_OUTPUTS_BIN::request req = AUTO_VAL_INIT(req);
+    req.outputs.resize(ring_size);
+    for (size_t j = 0; j < ring_size; ++j)
+    {
+      req.outputs[j].amount = in_key->amount;
+      req.outputs[j].index = absolute_offsets[j];
+    }
+    COMMAND_RPC_GET_OUTPUTS_BIN::response res = AUTO_VAL_INIT(res);
+    bool r;
+    {
+      const boost::lock_guard<boost::mutex> lock{m_daemon_rpc_mutex}; 
+      r = epee::net_utils::invoke_http_bin("/get_outs.bin", req, res, m_http_client, rpc_timeout);
+    }
+    THROW_WALLET_EXCEPTION_IF(!r, error::no_connection_to_daemon, "get_outs.bin");
+    THROW_WALLET_EXCEPTION_IF(res.status == CORE_RPC_STATUS_BUSY, error::daemon_busy, "get_outs.bin");
+    THROW_WALLET_EXCEPTION_IF(res.status != CORE_RPC_STATUS_OK, error::wallet_internal_error, "get_outs.bin");
+    THROW_WALLET_EXCEPTION_IF(res.outs.size() != ring_size, error::wallet_internal_error,
+      "daemon returned wrong response for get_outs.bin, wrong amounts count = " +
+      std::to_string(res.outs.size()) + ", expected " +  std::to_string(ring_size));
+
+    // copy pubkey pointers
+    std::vector<const crypto::public_key *> p_output_keys;
+    for (const COMMAND_RPC_GET_OUTPUTS_BIN::outkey &out : res.outs)
+      p_output_keys.push_back(&out.key);
+
+    // figure out real output index and secret key
+    size_t sec_index = -1;
+    for (size_t j = 0; j < ring_size; ++j)
+    {
+      if (res.outs[j].key == in_ephemeral.pub)
+      {
+        sec_index = j;
+        break;
+      }
+    }
+    THROW_WALLET_EXCEPTION_IF(sec_index >= ring_size, error::wallet_internal_error, "secret index not found");
+
+    // generate ring sig for this input
+    signatures.push_back(std::vector<crypto::signature>());
+    std::vector<crypto::signature>& sigs = signatures.back();
+    sigs.resize(in_key->key_offsets.size());
+    crypto::generate_ring_signature(sig_prefix_hash, in_key->k_image, p_output_keys, in_ephemeral.sec, sec_index, sigs.data());
+  }
+
+  std::string sig_str = "SpendProofV1";
+  for (const std::vector<crypto::signature>& ring_sig : signatures)
+    for (const crypto::signature& sig : ring_sig)
+       sig_str += tools::base58::encode(std::string((const char *)&sig, sizeof(crypto::signature)));
+  return sig_str;
+}
+//----------------------------------------------------------------------------------------------------
+bool wallet2::check_spend_proof(const crypto::hash &txid, const std::string &message, const std::string &sig_str)
+{
+  const std::string header = "SpendProofV1";
+  const size_t header_len = header.size();
+  THROW_WALLET_EXCEPTION_IF(sig_str.size() < header_len || sig_str.substr(0, header_len) != header, error::wallet_internal_error,
+    "Signature header check error");
+
+  // fetch tx from daemon
+  COMMAND_RPC_GET_TRANSACTIONS::request req = AUTO_VAL_INIT(req);
+  req.txs_hashes.push_back(epee::string_tools::pod_to_hex(txid));
+  req.decode_as_json = false;
+  COMMAND_RPC_GET_TRANSACTIONS::response res = AUTO_VAL_INIT(res);
+  bool r;
+  {
+    const boost::lock_guard<boost::mutex> lock{m_daemon_rpc_mutex}; 
+    r = epee::net_utils::invoke_http_json("/gettransactions", req, res, m_http_client, rpc_timeout);
+  }
+  THROW_WALLET_EXCEPTION_IF(!r, error::no_connection_to_daemon, "gettransactions");
+  THROW_WALLET_EXCEPTION_IF(res.status == CORE_RPC_STATUS_BUSY, error::daemon_busy, "gettransactions");
+  THROW_WALLET_EXCEPTION_IF(res.status != CORE_RPC_STATUS_OK, error::wallet_internal_error, "gettransactions");
+  THROW_WALLET_EXCEPTION_IF(res.txs.size() != 1, error::wallet_internal_error,
+    "daemon returned wrong response for gettransactions, wrong txs count = " +
+    std::to_string(res.txs.size()) + ", expected 1");
+  cryptonote::blobdata bd;
+  THROW_WALLET_EXCEPTION_IF(!epee::string_tools::parse_hexstr_to_binbuff(res.txs[0].as_hex, bd), error::wallet_internal_error, "failed to parse tx from hexstr");
+  cryptonote::transaction tx;
+  crypto::hash tx_hash, tx_prefix_hash;
+  THROW_WALLET_EXCEPTION_IF(!cryptonote::parse_and_validate_tx_from_blob(bd, tx, tx_hash, tx_prefix_hash), error::wallet_internal_error, "failed to parse tx from blob");
+  THROW_WALLET_EXCEPTION_IF(tx_hash != txid, error::wallet_internal_error, "txid mismatch");
+
+  // check signature size
+  size_t num_sigs = 0;
+  for(size_t i = 0; i < tx.vin.size(); ++i)
+  {
+    const txin_to_key* const in_key = boost::get<txin_to_key>(std::addressof(tx.vin[i]));
+    if (in_key != nullptr)
+      num_sigs += in_key->key_offsets.size();
+  }
+  std::vector<std::vector<crypto::signature>> signatures = { std::vector<crypto::signature>(1) };
+  const size_t sig_len = tools::base58::encode(std::string((const char *)&signatures[0][0], sizeof(crypto::signature))).size();
+  THROW_WALLET_EXCEPTION_IF(sig_str.size() != header_len + num_sigs * sig_len,
+    error::wallet_internal_error, "incorrect signature size");
+
+  // decode base58
+  signatures.clear();
+  size_t offset = header_len;
+  for(size_t i = 0; i < tx.vin.size(); ++i)
+  {
+    const txin_to_key* const in_key = boost::get<txin_to_key>(std::addressof(tx.vin[i]));
+    if (in_key == nullptr)
+      continue;
+    signatures.resize(signatures.size() + 1);
+    signatures.back().resize(in_key->key_offsets.size());
+    for (size_t j = 0; j < in_key->key_offsets.size(); ++j)
+    {
+      std::string sig_decoded;
+      THROW_WALLET_EXCEPTION_IF(!tools::base58::decode(sig_str.substr(offset, sig_len), sig_decoded), error::wallet_internal_error, "Signature decoding error");
+      THROW_WALLET_EXCEPTION_IF(sizeof(crypto::signature) != sig_decoded.size(), error::wallet_internal_error, "Signature decoding error");
+      memcpy(&signatures.back()[j], sig_decoded.data(), sizeof(crypto::signature));
+      offset += sig_len;
+    }
+  }
+
+  // get signature prefix hash
+  std::string sig_prefix_data((const char*)&txid, sizeof(crypto::hash));
+  sig_prefix_data += message;
+  crypto::hash sig_prefix_hash;
+  crypto::cn_fast_hash(sig_prefix_data.data(), sig_prefix_data.size(), sig_prefix_hash);
+
+  std::vector<std::vector<crypto::signature>>::const_iterator sig_iter = signatures.cbegin();
+  for(size_t i = 0; i < tx.vin.size(); ++i)
+  {
+    const txin_to_key* const in_key = boost::get<txin_to_key>(std::addressof(tx.vin[i]));
+    if (in_key == nullptr)
+      continue;
+
+    // get output pubkeys in the ring
+    COMMAND_RPC_GET_OUTPUTS_BIN::request req = AUTO_VAL_INIT(req);
+    const std::vector<uint64_t> absolute_offsets = cryptonote::relative_output_offsets_to_absolute(in_key->key_offsets);
+    req.outputs.resize(absolute_offsets.size());
+    for (size_t j = 0; j < absolute_offsets.size(); ++j)
+    {
+      req.outputs[j].amount = in_key->amount;
+      req.outputs[j].index = absolute_offsets[j];
+    }
+    COMMAND_RPC_GET_OUTPUTS_BIN::response res = AUTO_VAL_INIT(res);
+    bool r;
+    {
+      const boost::lock_guard<boost::mutex> lock{m_daemon_rpc_mutex}; 
+      r = epee::net_utils::invoke_http_bin("/get_outs.bin", req, res, m_http_client, rpc_timeout);
+    }
+    THROW_WALLET_EXCEPTION_IF(!r, error::no_connection_to_daemon, "get_outs.bin");
+    THROW_WALLET_EXCEPTION_IF(res.status == CORE_RPC_STATUS_BUSY, error::daemon_busy, "get_outs.bin");
+    THROW_WALLET_EXCEPTION_IF(res.status != CORE_RPC_STATUS_OK, error::wallet_internal_error, "get_outs.bin");
+    THROW_WALLET_EXCEPTION_IF(res.outs.size() != req.outputs.size(), error::wallet_internal_error,
+      "daemon returned wrong response for get_outs.bin, wrong amounts count = " +
+      std::to_string(res.outs.size()) + ", expected " +  std::to_string(req.outputs.size()));
+
+    // copy pointers
+    std::vector<const crypto::public_key *> p_output_keys;
+    for (const COMMAND_RPC_GET_OUTPUTS_BIN::outkey &out : res.outs)
+      p_output_keys.push_back(&out.key);
+
+    // check this ring
+    if (!crypto::check_ring_signature(sig_prefix_hash, in_key->k_image, p_output_keys, sig_iter->data()))
+      return false;
+    ++sig_iter;
+  }
+  THROW_WALLET_EXCEPTION_IF(sig_iter != signatures.cend(), error::wallet_internal_error, "Signature iterator didn't reach the end");
+  return true;
+}
+//----------------------------------------------------------------------------------------------------
 
 void wallet2::check_tx_key(const crypto::hash &txid, const crypto::secret_key &tx_key, const std::vector<crypto::secret_key> &additional_tx_keys, const cryptonote::account_public_address &address, uint64_t &received, bool &in_pool, uint64_t &confirmations)
 {