wallet: add command and RPC to sign/verify data

Signing is done using the spend key, since the view key may
be shared. This could be extended later, to let the user choose
which key (even a per tx key).
simplewallet's sign/verify API uses a file. The RPC uses a
string (simplewallet can't easily do strings since commands
receive a tokenized set of arguments).

src/wallet/wallet2.cpp

@@ -53,6 +53,7 @@ using namespace epee;
 #include "rapidjson/writer.h"
 #include "rapidjson/stringbuffer.h"
 #include "common/json_util.h"
+#include "common/base58.h"
 
 extern "C"
 {
@@ -3106,6 +3107,40 @@ std::string wallet2::get_tx_note(const crypto::hash &txid) const
     return std::string();
   return i->second;
 }
+
+std::string wallet2::sign(const std::string &data) const
+{
+  crypto::hash hash;
+  crypto::cn_fast_hash(data.data(), data.size(), hash);
+  const cryptonote::account_keys &keys = m_account.get_keys();
+  crypto::signature signature;
+  crypto::generate_signature(hash, keys.m_account_address.m_spend_public_key, keys.m_spend_secret_key, signature);
+  return std::string("SigV1") + tools::base58::encode(std::string((const char *)&signature, sizeof(signature)));
+}
+
+bool wallet2::verify(const std::string &data, const cryptonote::account_public_address &address, const std::string &signature) const
+{
+  const size_t header_len = strlen("SigV1");
+  if (signature.size() < header_len || signature.substr(0, header_len) != "SigV1") {
+    LOG_PRINT_L0("Signature header check error");
+    return false;
+  }
+  crypto::hash hash;
+  crypto::cn_fast_hash(data.data(), data.size(), hash);
+  std::string decoded;
+  if (!tools::base58::decode(signature.substr(header_len), decoded)) {
+    LOG_PRINT_L0("Signature decoding error");
+    return false;
+  }
+  crypto::signature s;
+  if (sizeof(s) != decoded.size()) {
+    LOG_PRINT_L0("Signature decoding error");
+    return false;
+  }
+  memcpy(&s, decoded.data(), sizeof(s));
+  return crypto::check_signature(hash, address.m_spend_public_key, s);
+}
+
 //----------------------------------------------------------------------------------------------------
 void wallet2::generate_genesis(cryptonote::block& b) {
   if (m_testnet)

src/wallet/wallet2.h

@@ -386,6 +386,9 @@ namespace tools
     void set_tx_note(const crypto::hash &txid, const std::string &note);
     std::string get_tx_note(const crypto::hash &txid) const;
 
+    std::string sign(const std::string &data) const;
+    bool verify(const std::string &data, const cryptonote::account_public_address &address, const std::string &signature) const;
+
   private:
     /*!
      * \brief  Stores wallet information to wallet file.

src/wallet/wallet_rpc_server.cpp

@@ -747,6 +747,42 @@ namespace tools
     return true;
   }
   //------------------------------------------------------------------------------------------------------------------------------
+  bool wallet_rpc_server::on_sign(const wallet_rpc::COMMAND_RPC_SIGN::request& req, wallet_rpc::COMMAND_RPC_SIGN::response& res, epee::json_rpc::error& er)
+  {
+    if (m_wallet.restricted())
+    {
+      er.code = WALLET_RPC_ERROR_CODE_DENIED;
+      er.message = "Command unavailable in restricted mode.";
+      return false;
+    }
+
+    res.signature = m_wallet.sign(req.data);
+    return true;
+  }
+  //------------------------------------------------------------------------------------------------------------------------------
+  bool wallet_rpc_server::on_verify(const wallet_rpc::COMMAND_RPC_VERIFY::request& req, wallet_rpc::COMMAND_RPC_VERIFY::response& res, epee::json_rpc::error& er)
+  {
+    if (m_wallet.restricted())
+    {
+      er.code = WALLET_RPC_ERROR_CODE_DENIED;
+      er.message = "Command unavailable in restricted mode.";
+      return false;
+    }
+
+    cryptonote::account_public_address address;
+    bool has_payment_id;
+    crypto::hash8 payment_id;
+    if(!get_account_integrated_address_from_str(address, has_payment_id, payment_id, m_wallet.testnet(), req.address))
+    {
+      er.code = WALLET_RPC_ERROR_CODE_WRONG_ADDRESS;
+      er.message = "";
+      return false;
+    }
+
+    res.good = m_wallet.verify(req.data, address, req.signature);
+    return true;
+  }
+  //------------------------------------------------------------------------------------------------------------------------------
   bool wallet_rpc_server::on_stop_wallet(const wallet_rpc::COMMAND_RPC_STOP_WALLET::request& req, wallet_rpc::COMMAND_RPC_STOP_WALLET::response& res, epee::json_rpc::error& er)
   {
     if (m_wallet.restricted())

src/wallet/wallet_rpc_server.h

@@ -80,6 +80,8 @@ namespace tools
         MAP_JON_RPC_WE("set_tx_notes",       on_set_tx_notes,       wallet_rpc::COMMAND_RPC_SET_TX_NOTES)
         MAP_JON_RPC_WE("get_tx_notes",       on_get_tx_notes,       wallet_rpc::COMMAND_RPC_GET_TX_NOTES)
         MAP_JON_RPC_WE("get_transfers",      on_get_transfers,      wallet_rpc::COMMAND_RPC_GET_TRANSFERS)
+        MAP_JON_RPC_WE("sign",               on_sign,               wallet_rpc::COMMAND_RPC_SIGN)
+        MAP_JON_RPC_WE("verify",             on_verify,             wallet_rpc::COMMAND_RPC_VERIFY)
       END_JSON_RPC_MAP()
     END_URI_MAP2()
 
@@ -103,6 +105,8 @@ namespace tools
       bool on_set_tx_notes(const wallet_rpc::COMMAND_RPC_SET_TX_NOTES::request& req, wallet_rpc::COMMAND_RPC_SET_TX_NOTES::response& res, epee::json_rpc::error& er);
       bool on_get_tx_notes(const wallet_rpc::COMMAND_RPC_GET_TX_NOTES::request& req, wallet_rpc::COMMAND_RPC_GET_TX_NOTES::response& res, epee::json_rpc::error& er);
       bool on_get_transfers(const wallet_rpc::COMMAND_RPC_GET_TRANSFERS::request& req, wallet_rpc::COMMAND_RPC_GET_TRANSFERS::response& res, epee::json_rpc::error& er);
+      bool on_sign(const wallet_rpc::COMMAND_RPC_SIGN::request& req, wallet_rpc::COMMAND_RPC_SIGN::response& res, epee::json_rpc::error& er);
+      bool on_verify(const wallet_rpc::COMMAND_RPC_VERIFY::request& req, wallet_rpc::COMMAND_RPC_VERIFY::response& res, epee::json_rpc::error& er);
 
       bool handle_command_line(const boost::program_options::variables_map& vm);
 

src/wallet/wallet_rpc_server_commands_defs.h

@@ -551,6 +551,51 @@ namespace wallet_rpc
     };
   };
 
-}
-}
+  struct COMMAND_RPC_SIGN
+  {
+    struct request
+    {
+      std::string data;
 
+      BEGIN_KV_SERIALIZE_MAP()
+        KV_SERIALIZE(data);
+      END_KV_SERIALIZE_MAP()
+    };
+
+    struct response
+    {
+      std::string signature;
+
+      BEGIN_KV_SERIALIZE_MAP()
+        KV_SERIALIZE(signature);
+      END_KV_SERIALIZE_MAP()
+    };
+  };
+
+  struct COMMAND_RPC_VERIFY
+  {
+    struct request
+    {
+      std::string data;
+      std::string address;
+      std::string signature;
+
+      BEGIN_KV_SERIALIZE_MAP()
+        KV_SERIALIZE(data);
+        KV_SERIALIZE(address);
+        KV_SERIALIZE(signature);
+      END_KV_SERIALIZE_MAP()
+    };
+
+    struct response
+    {
+      bool good;
+
+      BEGIN_KV_SERIALIZE_MAP()
+        KV_SERIALIZE(good);
+      END_KV_SERIALIZE_MAP()
+    };
+  };
+
+}
+}

src/wallet/wallet_rpc_server_error_codes.h

@@ -39,3 +39,4 @@
 #define WALLET_RPC_ERROR_CODE_TRANSFER_TYPE           -6
 #define WALLET_RPC_ERROR_CODE_DENIED                  -7
 #define WALLET_RPC_ERROR_CODE_WRONG_TXID              -8
+#define WALLET_RPC_ERROR_CODE_WRONG_SIGNATURE         -9