wallet: cold wallet transaction signing

This change adds the ability to create a new unsigned transaction
from a watch only wallet, and save it to a file. This file can
then be moved to another computer/VM where a cold wallet may load
it, sign it, and save it. That cold wallet does not need to have
a blockchain nor daemon. The signed transaction file can then be
moved back to the watch only wallet, which can load it and send
it to the daemon.

Two new simplewallet commands to use it:
sign_transfer (on the cold wallet)
submit_transfer (on the watch only wallet)

The transfer command used on a watch only wallet now writes an
unsigned transaction set in a file called 'unsigned_monero_tx'
instead of submitting the tx to the daemon as a normal wallet does.
The signed tx file is called 'signed_monero_tx'.

1 files changed, 73 insertions, 13 deletions

diff --git a/src/wallet/wallet2.h b/src/wallet/wallet2.h
index 89b613d34..d2d5fc7fd 100644
--- a/src/wallet/wallet2.h
+++ b/src/wallet/wallet2.h
@@ -151,6 +151,25 @@ namespace tools
         m_amount_in(utd.m_amount_in), m_amount_out(utd.m_amount_out), m_change(utd.m_change), m_block_height(height), m_dests(utd.m_dests), m_payment_id(utd.m_payment_id), m_timestamp(utd.m_timestamp) {}
     };
 
+    struct tx_construction_data
+    {
+      std::vector<cryptonote::tx_source_entry> sources;
+      std::vector<cryptonote::tx_destination_entry> destinations;
+      cryptonote::tx_destination_entry change_dts;
+      std::vector<uint8_t> extra;
+      uint64_t unlock_time;
+      bool use_rct;
+
+      BEGIN_SERIALIZE_OBJECT()
+        FIELD(sources)
+        FIELD(destinations)
+        FIELD(change_dts)
+        FIELD(extra)
+        VARINT_FIELD(unlock_time)
+        FIELD(use_rct)
+      END_SERIALIZE()
+    };
+
     typedef std::vector<transfer_details> transfer_container;
     typedef std::unordered_multimap<crypto::hash, payment_details> payment_container;
 
@@ -160,10 +179,41 @@ namespace tools
       uint64_t dust, fee;
       bool dust_added_to_fee;
       cryptonote::tx_destination_entry change_dts;
-      std::list<transfer_container::iterator> selected_transfers;
+      std::list<size_t> selected_transfers;
       std::string key_images;
       crypto::secret_key tx_key;
       std::vector<cryptonote::tx_destination_entry> dests;
+
+      tx_construction_data construction_data;
+
+      BEGIN_SERIALIZE_OBJECT()
+        FIELD(tx)
+        VARINT_FIELD(dust)
+        VARINT_FIELD(fee)
+        FIELD(dust_added_to_fee)
+        FIELD(change_dts)
+        FIELD(selected_transfers)
+        FIELD(key_images)
+        FIELD(tx_key)
+        FIELD(dests)
+        FIELD(construction_data)
+      END_SERIALIZE()
+    };
+
+    struct unsigned_tx_set
+    {
+      std::vector<tx_construction_data> txes;
+      BEGIN_SERIALIZE_OBJECT()
+        FIELD(txes)
+      END_SERIALIZE()
+    };
+
+    struct signed_tx_set
+    {
+      std::vector<pending_tx> ptx;
+      BEGIN_SERIALIZE_OBJECT()
+        FIELD(ptx)
+      END_SERIALIZE()
     };
 
     struct keys_file_data
@@ -298,13 +348,16 @@ namespace tools
     template<typename T>
     void transfer_from(const std::vector<size_t> &outs, size_t num_outputs, uint64_t unlock_time, uint64_t needed_fee, T destination_split_strategy, const tx_dust_policy& dust_policy, const std::vector<uint8_t>& extra, cryptonote::transaction& tx, pending_tx &ptx);
     template<typename T>
-    void transfer_selected(const std::vector<cryptonote::tx_destination_entry>& dsts, const std::list<transfer_container::iterator> selected_transfers, size_t fake_outputs_count,
+    void transfer_selected(const std::vector<cryptonote::tx_destination_entry>& dsts, const std::list<size_t> selected_transfers, size_t fake_outputs_count,
       uint64_t unlock_time, uint64_t fee, const std::vector<uint8_t>& extra, T destination_split_strategy, const tx_dust_policy& dust_policy, cryptonote::transaction& tx, pending_tx &ptx);
-    void transfer_selected_rct(std::vector<cryptonote::tx_destination_entry> dsts, const std::list<transfer_container::iterator> selected_transfers, size_t fake_outputs_count,
+    void transfer_selected_rct(std::vector<cryptonote::tx_destination_entry> dsts, const std::list<size_t> selected_transfers, size_t fake_outputs_count,
       uint64_t unlock_time, uint64_t fee, const std::vector<uint8_t>& extra, cryptonote::transaction& tx, pending_tx &ptx);
 
     void commit_tx(pending_tx& ptx_vector);
     void commit_tx(std::vector<pending_tx>& ptx_vector);
+    bool save_tx(const std::vector<pending_tx>& ptx_vector, const std::string &filename);
+    bool sign_tx(const std::string &unsigned_filename, const std::string &signed_filename, std::function<bool(const unsigned_tx_set&)> accept_func = NULL);
+    bool load_tx(const std::string &signed_filename, std::vector<tools::wallet2::pending_tx> &ptx);
     std::vector<pending_tx> create_transactions(std::vector<cryptonote::tx_destination_entry> dsts, const size_t fake_outs_count, const uint64_t unlock_time, uint32_t priority, const std::vector<uint8_t> extra, bool trusted_daemon);
     std::vector<wallet2::pending_tx> create_transactions_2(std::vector<cryptonote::tx_destination_entry> dsts, const size_t fake_outs_count, const uint64_t unlock_time, uint32_t priority, const std::vector<uint8_t> extra, bool trusted_daemon);
     std::vector<wallet2::pending_tx> create_transactions_all(const cryptonote::account_public_address &address, const size_t fake_outs_count, const uint64_t unlock_time, uint32_t priority, const std::vector<uint8_t> extra, bool trusted_daemon);
@@ -406,8 +459,8 @@ namespace tools
     std::vector<size_t> select_available_unmixable_outputs(bool trusted_daemon);
     std::vector<size_t> select_available_mixable_outputs(bool trusted_daemon);
 
-    size_t pop_best_value_from(const transfer_container &transfers, std::vector<size_t> &unused_dust_indices, const std::list<transfer_container::iterator>& selected_transfers) const;
-    size_t pop_best_value(std::vector<size_t> &unused_dust_indices, const std::list<transfer_container::iterator>& selected_transfers) const;
+    size_t pop_best_value_from(const transfer_container &transfers, std::vector<size_t> &unused_dust_indices, const std::list<size_t>& selected_transfers) const;
+    size_t pop_best_value(std::vector<size_t> &unused_dust_indices, const std::list<size_t>& selected_transfers) const;
 
     void set_tx_note(const crypto::hash &txid, const std::string &note);
     std::string get_tx_note(const crypto::hash &txid) const;
@@ -445,7 +498,7 @@ namespace tools
     void fast_refresh(uint64_t stop_height, uint64_t &blocks_start_height, std::list<crypto::hash> &short_chain_history);
     void pull_next_blocks(uint64_t start_height, uint64_t &blocks_start_height, std::list<crypto::hash> &short_chain_history, const std::list<cryptonote::block_complete_entry> &prev_blocks, std::list<cryptonote::block_complete_entry> &blocks, std::vector<cryptonote::COMMAND_RPC_GET_BLOCKS_FAST::block_output_indices> &o_indices, bool &error);
     void process_blocks(uint64_t start_height, const std::list<cryptonote::block_complete_entry> &blocks, const std::vector<cryptonote::COMMAND_RPC_GET_BLOCKS_FAST::block_output_indices> &o_indices, uint64_t& blocks_added);
-    uint64_t select_transfers(uint64_t needed_money, std::vector<size_t> unused_transfers_indices, std::list<transfer_container::iterator>& selected_transfers, bool trusted_daemon);
+    uint64_t select_transfers(uint64_t needed_money, std::vector<size_t> unused_transfers_indices, std::list<size_t>& selected_transfers, bool trusted_daemon);
     bool prepare_file_names(const std::string& file_path);
     void process_unconfirmed(const cryptonote::transaction& tx, uint64_t height);
     void process_outgoing(const cryptonote::transaction& tx, uint64_t height, uint64_t ts, uint64_t spent, uint64_t received);
@@ -461,10 +514,10 @@ namespace tools
     uint64_t get_fee_multiplier(uint32_t priority, bool use_new_fee) const;
     float get_output_relatedness(const transfer_details &td0, const transfer_details &td1) const;
     std::vector<size_t> pick_prefered_rct_inputs(uint64_t needed_money) const;
-    void set_spent(transfer_details &td, uint64_t height);
-    void set_unspent(transfer_details &td);
+    void set_spent(size_t idx, uint64_t height);
+    void set_unspent(size_t idx);
     template<typename entry>
-    void get_outs(std::vector<std::vector<entry>> &outs, const std::list<transfer_container::iterator> &selected_transfers, size_t fake_outputs_count);
+    void get_outs(std::vector<std::vector<entry>> &outs, const std::list<size_t> &selected_transfers, size_t fake_outputs_count);
 
     cryptonote::account_base m_account;
     std::string m_daemon_address;
@@ -736,7 +789,7 @@ namespace tools
 
     // randomly select inputs for transaction
     // throw if requested send amount is greater than amount available to send
-    std::list<transfer_container::iterator> selected_transfers;
+    std::list<size_t> selected_transfers;
     uint64_t found_money = select_transfers(needed_money, unused_transfers_indices, selected_transfers, trusted_daemon);
     THROW_WALLET_EXCEPTION_IF(found_money < needed_money, error::not_enough_money, found_money, needed_money - fee, fee);
 
@@ -748,8 +801,9 @@ namespace tools
     {
       COMMAND_RPC_GET_RANDOM_OUTPUTS_FOR_AMOUNTS::request req = AUTO_VAL_INIT(req);
       req.outs_count = fake_outputs_count + 1;// add one to make possible (if need) to skip real output key
-      BOOST_FOREACH(transfer_container::iterator it, selected_transfers)
+      BOOST_FOREACH(size_t idx, selected_transfers)
       {
+        const transfer_container::const_iterator it = m_transfers.begin() + idx;
         THROW_WALLET_EXCEPTION_IF(it->m_tx.vout.size() <= it->m_internal_output_index, error::wallet_internal_error,
           "m_internal_output_index = " + std::to_string(it->m_internal_output_index) +
           " is greater or equal to outputs count = " + std::to_string(it->m_tx.vout.size()));
@@ -780,11 +834,11 @@ namespace tools
     //prepare inputs
     size_t i = 0;
     std::vector<cryptonote::tx_source_entry> sources;
-    BOOST_FOREACH(transfer_container::iterator it, selected_transfers)
+    BOOST_FOREACH(size_t idx, selected_transfers)
     {
       sources.resize(sources.size()+1);
       cryptonote::tx_source_entry& src = sources.back();
-      transfer_details& td = *it;
+      const transfer_details& td = m_transfers[idx];
       src.amount = td.amount();
       src.rct = false;
       //paste mixin transaction
@@ -871,6 +925,12 @@ namespace tools
     ptx.selected_transfers = selected_transfers;
     ptx.tx_key = tx_key;
     ptx.dests = dsts;
+    ptx.construction_data.sources = sources;
+    ptx.construction_data.destinations = dsts;
+    ptx.construction_data.change_dts = change_dts;
+    ptx.construction_data.extra = tx.extra;
+    ptx.construction_data.unlock_time = unlock_time;
+    ptx.construction_data.use_rct = false;
   }