Merge pull request bitshares#507 from btcinshares/sign_memo_api

Proposal: expose sign/read memo API to wallet

Author: oxarbitrage

libraries/wallet/include/graphene/wallet/wallet.hpp

@@ -786,6 +786,22 @@ class wallet_api
       transaction_id_type get_transaction_id( const signed_transaction& trx )const { return trx.id(); }
 
 
+      /** Sign a memo message.
+       *
+       * @param from the name or id of signing account; or a public key.
+       * @param to the name or id of receiving account; or a public key.
+       * @param memo text to sign.
+       */
+      memo_data sign_memo(string from, string to, string memo);
+
+      /** Read a memo.
+       *
+       * @param memo JSON-enconded memo.
+       * @returns string with decrypted message..
+       */
+      string read_memo(const memo_data& memo);
+
+
       /** These methods are used for stealth transfers */
       ///@{
       /**
@@ -1718,6 +1734,8 @@ FC_API( graphene::wallet::wallet_api,
         (flood_network)
         (network_add_nodes)
         (network_get_connected_peers)
+        (sign_memo)
+        (read_memo)
         (set_key_label)
         (get_key_label)
         (get_public_key)

libraries/wallet/wallet.cpp

@@ -1877,6 +1877,56 @@ class wallet_api_impl
       return tx;
    }
 
+   memo_data sign_memo(string from, string to, string memo)
+   {
+      FC_ASSERT( !self.is_locked() );
+
+      memo_data md = memo_data();
+
+      // get account memo key, if that fails, try a pubkey
+      try {
+         account_object from_account = get_account(from);
+         md.from = from_account.options.memo_key;
+      } catch (const fc::exception& e) {
+         md.from =  self.get_public_key( from );
+      }
+      // same as above, for destination key
+      try {
+         account_object to_account = get_account(to);
+         md.to = to_account.options.memo_key;
+      } catch (const fc::exception& e) {
+         md.to = self.get_public_key( to );
+      }
+
+      md.set_message(get_private_key(md.from), md.to, memo);
+      return md;
+   }
+
+   string read_memo(const memo_data& md)
+   {
+      FC_ASSERT(!is_locked());
+      std::string clear_text;
+
+      const memo_data *memo = &md;
+
+      try {
+         FC_ASSERT(_keys.count(memo->to) || _keys.count(memo->from), "Memo is encrypted to a key ${to} or ${from} not in this wallet.", ("to", memo->to)("from",memo->from));
+         if( _keys.count(memo->to) ) {
+            auto my_key = wif_to_key(_keys.at(memo->to));
+            FC_ASSERT(my_key, "Unable to recover private key to decrypt memo. Wallet may be corrupted.");
+            clear_text = memo->get_message(*my_key, memo->from);
+         } else {
+            auto my_key = wif_to_key(_keys.at(memo->from));
+            FC_ASSERT(my_key, "Unable to recover private key to decrypt memo. Wallet may be corrupted.");
+            clear_text = memo->get_message(*my_key, memo->to);
+         }
+      } catch (const fc::exception& e) {
+         elog("Error when decrypting memo: ${e}", ("e", e.to_detail_string()));
+      }
+
+      return clear_text;
+   }
+
    signed_transaction sell_asset(string seller_account,
                                  string amount_to_sell,
                                  string symbol_to_sell,
@@ -3783,6 +3833,18 @@ signed_transaction wallet_api::cancel_order(object_id_type order_id, bool broadc
    return my->cancel_order(order_id, broadcast);
 }
 
+memo_data wallet_api::sign_memo(string from, string to, string memo)
+{
+   FC_ASSERT(!is_locked());
+   return my->sign_memo(from, to, memo);
+}
+
+string wallet_api::read_memo(const memo_data& memo)
+{
+   FC_ASSERT(!is_locked());
+   return my->read_memo(memo);
+}
+
 string wallet_api::get_key_label( public_key_type key )const
 {
    auto key_itr   = my->_wallet.labeled_keys.get<by_key>().find(key);