Encrypted payment IDs

A payment ID may be encrypted using the tx secret key and the
receiver's public view key. The receiver can decrypt it with
the tx public key and the receiver's secret view key.

Using integrated addresses now cause the payment IDs to be
encrypted. Payment IDs used manually are not encrypted by default,
but can be encrypted using the new 'encrypt_payment_id' field
in the transfer and transfer_split RPC calls. It is not possible
to use an encrypted payment ID by specifying a manual simplewallet
transfer/transfer_new command, though this is just a limitation
due to input parsing.

src/wallet/wallet2.cpp

@@ -150,6 +150,7 @@ void wallet2::process_new_transaction(const cryptonote::transaction& tx, uint64_
   process_unconfirmed(tx);
   std::vector<size_t> outs;
   uint64_t tx_money_got_in_outs = 0;
+  crypto::public_key tx_pub_key = null_pkey;
 
   std::vector<tx_extra_field> tx_extra_fields;
   if(!parse_tx_extra(tx.extra, tx_extra_fields))
@@ -170,7 +171,7 @@ void wallet2::process_new_transaction(const cryptonote::transaction& tx, uint64_
       return;
     }
 
-    crypto::public_key tx_pub_key = pub_key_field.pub_key;
+    tx_pub_key = pub_key_field.pub_key;
     bool r = lookup_acc_outs(m_account.get_keys(), tx, tx_pub_key, outs, tx_money_got_in_outs);
     THROW_WALLET_EXCEPTION_IF(!r, error::acc_outs_lookup_error, tx, tx_pub_key, m_account.get_keys());
 
@@ -236,9 +237,26 @@ void wallet2::process_new_transaction(const cryptonote::transaction& tx, uint64_
   crypto::hash payment_id = null_hash;
   if (find_tx_extra_field_by_type(tx_extra_fields, extra_nonce))
   {
-    if(get_payment_id_from_tx_extra_nonce(extra_nonce.nonce, payment_id))
+    bool encrypted;
+    if(get_payment_id_from_tx_extra_nonce(extra_nonce.nonce, payment_id, encrypted) && encrypted)
     {
       // We got a payment ID to go with this tx
+      LOG_PRINT_L2("Found encrypted payment ID: " << payment_id);
+      if (tx_pub_key != null_pkey)
+      {
+        if (!decrypt_payment_id(payment_id, tx_pub_key, m_account.get_keys().m_view_secret_key))
+        {
+          LOG_PRINT_L0("Failed to decrypt payment ID: " << payment_id);
+        }
+        else
+        {
+          LOG_PRINT_L2("Decrypted payment ID: " << payment_id);
+        }
+      }
+      else
+      {
+        LOG_PRINT_L1("No public key found in tx, unable to decrypt payment id");
+      }
     }
   }
   uint64_t received = (tx_money_spent_in_ins < tx_money_got_in_outs) ? tx_money_got_in_outs - tx_money_spent_in_ins : 0;

src/wallet/wallet_rpc_server.cpp

@@ -117,7 +117,7 @@ namespace tools
   }
 
   //------------------------------------------------------------------------------------------------------------------------------
-  bool wallet_rpc_server::validate_transfer(const std::list<wallet_rpc::transfer_destination> destinations, std::string payment_id, std::vector<cryptonote::tx_destination_entry>& dsts, std::vector<uint8_t>& extra, epee::json_rpc::error& er)
+  bool wallet_rpc_server::validate_transfer(const std::list<wallet_rpc::transfer_destination> destinations, std::string payment_id, bool encrypt_payment_id, std::vector<cryptonote::tx_destination_entry>& dsts, std::vector<uint8_t>& extra, epee::json_rpc::error& er)
   {
     crypto::hash integrated_payment_id = cryptonote::null_hash;
     for (auto it = destinations.begin(); it != destinations.end(); it++)
@@ -144,6 +144,9 @@ namespace tools
         }
         integrated_payment_id = new_payment_id;
       }
+
+      // integrated addresses imply encrypted payment id
+      encrypt_payment_id = true;
     }
 
     if (!payment_id.empty())
@@ -161,7 +164,7 @@ namespace tools
       }
 
       std::string extra_nonce;
-      cryptonote::set_payment_id_to_tx_extra_nonce(extra_nonce, payment_id);
+      cryptonote::set_payment_id_to_tx_extra_nonce(extra_nonce, payment_id, encrypt_payment_id);
       
       /* Append Payment ID data into extra */
       if (!cryptonote::add_extra_nonce_to_tx_extra(extra, extra_nonce)) {
@@ -189,7 +192,7 @@ namespace tools
     }
 
     // validate the transfer requested and populate dsts & extra
-    if (!validate_transfer(req.destinations, req.payment_id, dsts, extra, er))
+    if (!validate_transfer(req.destinations, req.payment_id, req.encrypt_payment_id, dsts, extra, er))
     {
       return false;
     }
@@ -247,7 +250,7 @@ namespace tools
     }
 
     // validate the transfer requested and populate dsts & extra; RPC_TRANSFER::request and RPC_TRANSFER_SPLIT::request are identical types.
-    if (!validate_transfer(req.destinations, req.payment_id, dsts, extra, er))
+    if (!validate_transfer(req.destinations, req.payment_id, req.encrypt_payment_id, dsts, extra, er))
     {
       return false;
     }

src/wallet/wallet_rpc_server.h

@@ -79,7 +79,7 @@ namespace tools
       //json_rpc
       bool on_getbalance(const wallet_rpc::COMMAND_RPC_GET_BALANCE::request& req, wallet_rpc::COMMAND_RPC_GET_BALANCE::response& res, epee::json_rpc::error& er);
       bool on_getaddress(const wallet_rpc::COMMAND_RPC_GET_ADDRESS::request& req, wallet_rpc::COMMAND_RPC_GET_ADDRESS::response& res, epee::json_rpc::error& er);
-      bool validate_transfer(const std::list<wallet_rpc::transfer_destination> destinations, const std::string payment_id, std::vector<cryptonote::tx_destination_entry>& dsts, std::vector<uint8_t>& extra, epee::json_rpc::error& er);
+      bool validate_transfer(const std::list<wallet_rpc::transfer_destination> destinations, const std::string payment_id, bool encrypt_payment_id, std::vector<cryptonote::tx_destination_entry>& dsts, std::vector<uint8_t>& extra, epee::json_rpc::error& er);
       bool on_transfer(const wallet_rpc::COMMAND_RPC_TRANSFER::request& req, wallet_rpc::COMMAND_RPC_TRANSFER::response& res, epee::json_rpc::error& er);
       bool on_transfer_split(const wallet_rpc::COMMAND_RPC_TRANSFER_SPLIT::request& req, wallet_rpc::COMMAND_RPC_TRANSFER_SPLIT::response& res, epee::json_rpc::error& er);
       bool on_sweep_dust(const wallet_rpc::COMMAND_RPC_SWEEP_DUST::request& req, wallet_rpc::COMMAND_RPC_SWEEP_DUST::response& res, epee::json_rpc::error& er);

src/wallet/wallet_rpc_server_commands_defs.h

@@ -97,6 +97,7 @@ namespace wallet_rpc
       uint64_t mixin;
       uint64_t unlock_time;
       std::string payment_id;
+      bool encrypt_payment_id;
 
       BEGIN_KV_SERIALIZE_MAP()
         KV_SERIALIZE(destinations)
@@ -104,6 +105,7 @@ namespace wallet_rpc
         KV_SERIALIZE(mixin)
         KV_SERIALIZE(unlock_time)
         KV_SERIALIZE(payment_id)
+        KV_SERIALIZE(encrypt_payment_id)
       END_KV_SERIALIZE_MAP()
     };
 
@@ -127,6 +129,7 @@ namespace wallet_rpc
       uint64_t unlock_time;
       std::string payment_id;
       bool new_algorithm;
+      bool encrypt_payment_id;
 
       BEGIN_KV_SERIALIZE_MAP()
         KV_SERIALIZE(destinations)
@@ -135,6 +138,7 @@ namespace wallet_rpc
         KV_SERIALIZE(unlock_time)
         KV_SERIALIZE(payment_id)
         KV_SERIALIZE(new_algorithm)
+        KV_SERIALIZE(encrypt_payment_id)
       END_KV_SERIALIZE_MAP()
     };