Merge pull request #425

79c95c1 simplewallet: bump default mixin from 3 to 4 (moneromooo-monero)
ac90d48 from hard fork 2, all outputs must be decomposed (moneromooo-monero)
90ccad1 from hard fork 2, claim a quantized reward in coinbase (moneromooo-monero)
22b1570 cryptonote_format_utils: add a function to tell if an amount is canonical (moneromooo-monero)

9 files changed, 121 insertions, 53 deletions

diff --git a/src/cryptonote_config.h b/src/cryptonote_config.h
index c6aa064cf..b042088bd 100644
--- a/src/cryptonote_config.h
+++ b/src/cryptonote_config.h
@@ -118,6 +118,7 @@ namespace config
   uint64_t const DEFAULT_FEE_ATOMIC_XMR_PER_KB = 500; // Just a placeholder!  Change me!
   uint8_t const FEE_CALCULATION_MAX_RETRIES = 10;
   uint64_t const DEFAULT_DUST_THRESHOLD = ((uint64_t)10000000000); // pow(10, 10)
+  uint64_t const BASE_REWARD_CLAMP_THRESHOLD = ((uint64_t)100000000); // pow(10, 8)
   std::string const P2P_REMOTE_DEBUG_TRUSTED_PUB_KEY = "0000000000000000000000000000000000000000000000000000000000000000";
 
   uint64_t const CRYPTONOTE_PUBLIC_ADDRESS_BASE58_PREFIX = 18;
diff --git a/src/cryptonote_core/blockchain.cpp b/src/cryptonote_core/blockchain.cpp
index 3d96f6f5d..e06c3c08c 100644
--- a/src/cryptonote_core/blockchain.cpp
+++ b/src/cryptonote_core/blockchain.cpp
@@ -975,6 +975,14 @@ bool Blockchain::validate_miner_transaction(const block& b, size_t cumulative_bl
             return false;
         }
     }
+    else
+    {
+        // from hard fork 2, since a miner can claim less than the full block reward, we update the base_reward
+        // to show the amount of coins that were actually generated, the remainder will be pushed back for later
+        // emission. This modifies the emission curve very slightly.
+        CHECK_AND_ASSERT_MES(money_in_use - fee <= base_reward, false, "base reward calculation bug");
+        base_reward = money_in_use - fee;
+    }
     return true;
 }
 //------------------------------------------------------------------
@@ -1093,7 +1101,7 @@ bool Blockchain::create_block_template(block& b, const account_public_address& m
      block size, so first miner transaction generated with fake amount of money, and with phase we know think we know expected block size
      */
     //make blocks coin-base tx looks close to real coinbase tx to get truthful blob size
-    bool r = construct_miner_tx(height, median_size, already_generated_coins, txs_size, fee, miner_address, b.miner_tx, ex_nonce, 11);
+    bool r = construct_miner_tx(height, median_size, already_generated_coins, txs_size, fee, miner_address, b.miner_tx, ex_nonce, 11, m_hardfork->get_current_version());
     CHECK_AND_ASSERT_MES(r, false, "Failed to construc miner tx, first chance");
     size_t cumulative_size = txs_size + get_object_blobsize(b.miner_tx);
 #if defined(DEBUG_CREATE_BLOCK_TEMPLATE)
@@ -1102,7 +1110,7 @@ bool Blockchain::create_block_template(block& b, const account_public_address& m
 #endif
     for (size_t try_count = 0; try_count != 10; ++try_count)
     {
-        r = construct_miner_tx(height, median_size, already_generated_coins, cumulative_size, fee, miner_address, b.miner_tx, ex_nonce, 11);
+        r = construct_miner_tx(height, median_size, already_generated_coins, cumulative_size, fee, miner_address, b.miner_tx, ex_nonce, 11, m_hardfork->get_current_version());
 
         CHECK_AND_ASSERT_MES(r, false, "Failed to construc miner tx, second chance");
         size_t coinbase_blob_size = get_object_blobsize(b.miner_tx);
@@ -1964,6 +1972,23 @@ bool Blockchain::check_tx_inputs(const transaction& tx, uint64_t& max_used_block
     return true;
 }
 //------------------------------------------------------------------
+bool Blockchain::check_tx_outputs(const transaction& tx)
+{
+    LOG_PRINT_L3("Blockchain::" << __func__);
+    CRITICAL_REGION_LOCAL(m_blockchain_lock);
+
+    // from hard fork 2, we forbid dust and compound outputs
+    if (m_hardfork->get_current_version() >= 2) {
+      BOOST_FOREACH(auto &o, tx.vout) {
+        if (!is_valid_decomposed_amount(o.amount)) {
+          return false;
+        }
+      }
+    }
+
+    return true;
+}
+//------------------------------------------------------------------
 bool Blockchain::have_tx_keyimges_as_spent(const transaction &tx) const
 {
     LOG_PRINT_L3("Blockchain::" << __func__);
diff --git a/src/cryptonote_core/blockchain.h b/src/cryptonote_core/blockchain.h
index a248682fc..3a663a342 100644
--- a/src/cryptonote_core/blockchain.h
+++ b/src/cryptonote_core/blockchain.h
@@ -134,6 +134,7 @@ namespace cryptonote
     bool store_blockchain();
 
     bool check_tx_inputs(const transaction& tx, uint64_t& pmax_used_block_height, crypto::hash& max_used_block_id, bool kept_by_block = false);
+    bool check_tx_outputs(const transaction& tx);
     uint64_t get_current_cumulative_blocksize_limit() const;
     bool is_storing_blockchain()const{return m_is_blockchain_storing;}
     uint64_t block_difficulty(uint64_t i) const;
diff --git a/src/cryptonote_core/cryptonote_format_utils.cpp b/src/cryptonote_core/cryptonote_format_utils.cpp
index 979420e35..56a3dd8de 100644
--- a/src/cryptonote_core/cryptonote_format_utils.cpp
+++ b/src/cryptonote_core/cryptonote_format_utils.cpp
@@ -40,6 +40,29 @@ using namespace epee;
 
 #define ENCRYPTED_PAYMENT_ID_TAIL 0x8d
 
+static const uint64_t valid_decomposed_outputs[] = {
+  (uint64_t)1, (uint64_t)2, (uint64_t)3, (uint64_t)4, (uint64_t)5, (uint64_t)6, (uint64_t)7, (uint64_t)8, (uint64_t)9, // 1 piconero
+  (uint64_t)10, (uint64_t)20, (uint64_t)30, (uint64_t)40, (uint64_t)50, (uint64_t)60, (uint64_t)70, (uint64_t)80, (uint64_t)90,
+  (uint64_t)100, (uint64_t)200, (uint64_t)300, (uint64_t)400, (uint64_t)500, (uint64_t)600, (uint64_t)700, (uint64_t)800, (uint64_t)900,
+  (uint64_t)1000, (uint64_t)2000, (uint64_t)3000, (uint64_t)4000, (uint64_t)5000, (uint64_t)6000, (uint64_t)7000, (uint64_t)8000, (uint64_t)9000,
+  (uint64_t)10000, (uint64_t)20000, (uint64_t)30000, (uint64_t)40000, (uint64_t)50000, (uint64_t)60000, (uint64_t)70000, (uint64_t)80000, (uint64_t)90000,
+  (uint64_t)100000, (uint64_t)200000, (uint64_t)300000, (uint64_t)400000, (uint64_t)500000, (uint64_t)600000, (uint64_t)700000, (uint64_t)800000, (uint64_t)900000,
+  (uint64_t)1000000, (uint64_t)2000000, (uint64_t)3000000, (uint64_t)4000000, (uint64_t)5000000, (uint64_t)6000000, (uint64_t)7000000, (uint64_t)8000000, (uint64_t)9000000, // 1 micronero
+  (uint64_t)10000000, (uint64_t)20000000, (uint64_t)30000000, (uint64_t)40000000, (uint64_t)50000000, (uint64_t)60000000, (uint64_t)70000000, (uint64_t)80000000, (uint64_t)90000000,
+  (uint64_t)100000000, (uint64_t)200000000, (uint64_t)300000000, (uint64_t)400000000, (uint64_t)500000000, (uint64_t)600000000, (uint64_t)700000000, (uint64_t)800000000, (uint64_t)900000000,
+  (uint64_t)1000000000, (uint64_t)2000000000, (uint64_t)3000000000, (uint64_t)4000000000, (uint64_t)5000000000, (uint64_t)6000000000, (uint64_t)7000000000, (uint64_t)8000000000, (uint64_t)9000000000,
+  (uint64_t)10000000000, (uint64_t)20000000000, (uint64_t)30000000000, (uint64_t)40000000000, (uint64_t)50000000000, (uint64_t)60000000000, (uint64_t)70000000000, (uint64_t)80000000000, (uint64_t)90000000000,
+  (uint64_t)100000000000, (uint64_t)200000000000, (uint64_t)300000000000, (uint64_t)400000000000, (uint64_t)500000000000, (uint64_t)600000000000, (uint64_t)700000000000, (uint64_t)800000000000, (uint64_t)900000000000,
+  (uint64_t)1000000000000, (uint64_t)2000000000000, (uint64_t)3000000000000, (uint64_t)4000000000000, (uint64_t)5000000000000, (uint64_t)6000000000000, (uint64_t)7000000000000, (uint64_t)8000000000000, (uint64_t)9000000000000, // 1 monero
+  (uint64_t)10000000000000, (uint64_t)20000000000000, (uint64_t)30000000000000, (uint64_t)40000000000000, (uint64_t)50000000000000, (uint64_t)60000000000000, (uint64_t)70000000000000, (uint64_t)80000000000000, (uint64_t)90000000000000,
+  (uint64_t)100000000000000, (uint64_t)200000000000000, (uint64_t)300000000000000, (uint64_t)400000000000000, (uint64_t)500000000000000, (uint64_t)600000000000000, (uint64_t)700000000000000, (uint64_t)800000000000000, (uint64_t)900000000000000,
+  (uint64_t)1000000000000000, (uint64_t)2000000000000000, (uint64_t)3000000000000000, (uint64_t)4000000000000000, (uint64_t)5000000000000000, (uint64_t)6000000000000000, (uint64_t)7000000000000000, (uint64_t)8000000000000000, (uint64_t)9000000000000000,
+  (uint64_t)10000000000000000, (uint64_t)20000000000000000, (uint64_t)30000000000000000, (uint64_t)40000000000000000, (uint64_t)50000000000000000, (uint64_t)60000000000000000, (uint64_t)70000000000000000, (uint64_t)80000000000000000, (uint64_t)90000000000000000,
+  (uint64_t)100000000000000000, (uint64_t)200000000000000000, (uint64_t)300000000000000000, (uint64_t)400000000000000000, (uint64_t)500000000000000000, (uint64_t)600000000000000000, (uint64_t)700000000000000000, (uint64_t)800000000000000000, (uint64_t)900000000000000000,
+  (uint64_t)1000000000000000000, (uint64_t)2000000000000000000, (uint64_t)3000000000000000000, (uint64_t)4000000000000000000, (uint64_t)5000000000000000000, (uint64_t)6000000000000000000, (uint64_t)7000000000000000000, (uint64_t)8000000000000000000, (uint64_t)9000000000000000000, // 1 meganero
+  (uint64_t)10000000000000000000ull
+};
+
 namespace cryptonote
 {
   //---------------------------------------------------------------
@@ -82,7 +105,7 @@ namespace cryptonote
     return true;
   }
   //---------------------------------------------------------------
-  bool construct_miner_tx(size_t height, size_t median_size, uint64_t already_generated_coins, size_t current_block_size, uint64_t fee, const account_public_address &miner_address, transaction& tx, const blobdata& extra_nonce, size_t max_outs) {
+  bool construct_miner_tx(size_t height, size_t median_size, uint64_t already_generated_coins, size_t current_block_size, uint64_t fee, const account_public_address &miner_address, transaction& tx, const blobdata& extra_nonce, size_t max_outs, uint8_t hard_fork_version) {
     tx.vin.clear();
     tx.vout.clear();
     tx.extra.clear();
@@ -102,6 +125,15 @@ namespace cryptonote
       LOG_PRINT_L0("Block is too big");
       return false;
     }
+
+    // from hard fork 2, we cut out the low significant digits. This makes the tx smaller, and
+    // keeps the paid amount almost the same. The unpaid remainder gets pushed back to the
+    // emission schedule
+    if (hard_fork_version >= 2)
+    {
+        block_reward = block_reward - block_reward % ::config::BASE_REWARD_CLAMP_THRESHOLD;
+    }
+
 #if defined(DEBUG_CREATE_BLOCK_TEMPLATE)
     LOG_PRINT_L1("Creating block template: reward " << block_reward <<
       ", fee " << fee)
@@ -109,7 +141,7 @@ namespace cryptonote
     block_reward += fee;
 
     std::vector<uint64_t> out_amounts;
-    decompose_amount_into_digits(block_reward, ::config::DEFAULT_DUST_THRESHOLD,
+    decompose_amount_into_digits(block_reward, hard_fork_version >= 2 ? 0 : ::config::DEFAULT_DUST_THRESHOLD,
       [&out_amounts](uint64_t a_chunk) { out_amounts.push_back(a_chunk); },
       [&out_amounts](uint64_t a_dust) { out_amounts.push_back(a_dust); });
 
@@ -922,4 +954,11 @@ namespace cryptonote
     return get_tx_tree_hash(txs_ids);
   }
   //---------------------------------------------------------------
+  bool is_valid_decomposed_amount(uint64_t amount)
+  {
+    const uint64_t *begin = valid_decomposed_outputs;
+    const uint64_t *end = valid_decomposed_outputs + sizeof(valid_decomposed_outputs) / sizeof(valid_decomposed_outputs[0]);
+    return std::binary_search(begin, end, amount);
+  }
+  //---------------------------------------------------------------
 }
diff --git a/src/cryptonote_core/cryptonote_format_utils.h b/src/cryptonote_core/cryptonote_format_utils.h
index 7768500b5..202919822 100644
--- a/src/cryptonote_core/cryptonote_format_utils.h
+++ b/src/cryptonote_core/cryptonote_format_utils.h
@@ -44,7 +44,7 @@ namespace cryptonote
   crypto::hash get_transaction_prefix_hash(const transaction_prefix& tx);
   bool parse_and_validate_tx_from_blob(const blobdata& tx_blob, transaction& tx, crypto::hash& tx_hash, crypto::hash& tx_prefix_hash);
   bool parse_and_validate_tx_from_blob(const blobdata& tx_blob, transaction& tx);
-  bool construct_miner_tx(size_t height, size_t median_size, uint64_t already_generated_coins, size_t current_block_size, uint64_t fee, const account_public_address &miner_address, transaction& tx, const blobdata& extra_nonce = blobdata(), size_t max_outs = 1);
+  bool construct_miner_tx(size_t height, size_t median_size, uint64_t already_generated_coins, size_t current_block_size, uint64_t fee, const account_public_address &miner_address, transaction& tx, const blobdata& extra_nonce = blobdata(), size_t max_outs = 1, uint8_t hard_fork_version = 1);
   bool encrypt_payment_id(crypto::hash8 &payment_id, const crypto::public_key &public_key, const crypto::secret_key &secret_key);
   bool decrypt_payment_id(crypto::hash8 &payment_id, const crypto::public_key &public_key, const crypto::secret_key &secret_key);
 
@@ -231,6 +231,7 @@ namespace cryptonote
   void get_tx_tree_hash(const std::vector<crypto::hash>& tx_hashes, crypto::hash& h);
   crypto::hash get_tx_tree_hash(const std::vector<crypto::hash>& tx_hashes);
   crypto::hash get_tx_tree_hash(const block& b);
+  bool is_valid_decomposed_amount(uint64_t amount);
 
 #define CHECKED_GET_SPECIFIC_VARIANT(variant_var, specific_type, variable_name, fail_return_val) \
   CHECK_AND_ASSERT_MES(variant_var.type() == typeid(specific_type), fail_return_val, "wrong variant type: " << variant_var.type().name() << ", expected " << typeid(specific_type).name()); \
diff --git a/src/cryptonote_core/tx_pool.cpp b/src/cryptonote_core/tx_pool.cpp
index 12fd3fe62..dce64db99 100644
--- a/src/cryptonote_core/tx_pool.cpp
+++ b/src/cryptonote_core/tx_pool.cpp
@@ -125,6 +125,12 @@ namespace cryptonote
       }
     }
 
+    if (!m_blockchain.check_tx_outputs(tx))
+    {
+      LOG_PRINT_L1("Transaction with id= "<< id << " has at least one invalid outout");
+      tvc.m_verifivation_failed = true;
+      return false;
+    }
 
     crypto::hash max_used_block_id = null_hash;
     uint64_t max_used_block_height = 0;
diff --git a/src/simplewallet/simplewallet.cpp b/src/simplewallet/simplewallet.cpp
index fa41e1d42..6008a9a04 100644
--- a/src/simplewallet/simplewallet.cpp
+++ b/src/simplewallet/simplewallet.cpp
@@ -74,7 +74,7 @@ typedef cryptonote::simple_wallet sw;
 
 unsigned int epee::g_test_dbg_lock_sleep = 0;
 
-#define DEFAULT_MIX 3
+#define DEFAULT_MIX 4
 
 namespace
 {
diff --git a/src/wallet/wallet2.cpp b/src/wallet/wallet2.cpp
index 12f69e6fe..b27b303df 100644
--- a/src/wallet/wallet2.cpp
+++ b/src/wallet/wallet2.cpp
@@ -1143,7 +1143,7 @@ uint64_t wallet2::select_transfers(uint64_t needed_money, bool add_dust, uint64_
     const transfer_details& td = m_transfers[i];
     if (!td.m_spent && is_transfer_unlocked(td))
     {
-      if (dust < td.amount())
+      if (dust < td.amount() && is_valid_decomposed_amount(td.amount()))
         unused_transfers_indices.push_back(i);
       else
         unused_dust_indices.push_back(i);
@@ -1572,14 +1572,17 @@ void wallet2::transfer_selected(const std::vector<cryptonote::tx_destination_ent
     change_dts.amount = found_money - needed_money;
   }
 
+  std::vector<cryptonote::tx_destination_entry> splitted_dsts, dust_dsts;
   uint64_t dust = 0;
-  std::vector<cryptonote::tx_destination_entry> splitted_dsts;
-  destination_split_strategy(dsts, change_dts, dust_policy.dust_threshold, splitted_dsts, dust);
-  THROW_WALLET_EXCEPTION_IF(dust_policy.dust_threshold < dust, error::wallet_internal_error, "invalid dust value: dust = " +
-    std::to_string(dust) + ", dust_threshold = " + std::to_string(dust_policy.dust_threshold));
-  if (0 != dust && !dust_policy.add_to_fee)
-  {
-    splitted_dsts.push_back(cryptonote::tx_destination_entry(dust, dust_policy.addr_for_dust));
+  destination_split_strategy(dsts, change_dts, dust_policy.dust_threshold, splitted_dsts, dust_dsts);
+  BOOST_FOREACH(auto& d, dust_dsts) {
+    THROW_WALLET_EXCEPTION_IF(dust_policy.dust_threshold < d.amount, error::wallet_internal_error, "invalid dust value: dust = " +
+      std::to_string(d.amount) + ", dust_threshold = " + std::to_string(dust_policy.dust_threshold));
+  }
+  BOOST_FOREACH(auto& d, dust_dsts) {
+    if (!dust_policy.add_to_fee)
+      splitted_dsts.push_back(cryptonote::tx_destination_entry(d.amount, dust_policy.addr_for_dust));
+    dust += d.amount;
   }
 
   crypto::secret_key tx_key;
@@ -1669,7 +1672,7 @@ std::vector<wallet2::pending_tx> wallet2::create_transactions_2(std::vector<cryp
     const transfer_details& td = m_transfers[i];
     if (!td.m_spent && is_transfer_unlocked(td))
     {
-      if (::config::DEFAULT_DUST_THRESHOLD <= td.amount())
+      if (is_valid_decomposed_amount(td.amount()))
         unused_transfers_indices.push_back(i);
       else
         unused_dust_indices.push_back(i);
@@ -1923,11 +1926,12 @@ void wallet2::transfer_dust(size_t num_outputs, uint64_t unlock_time, uint64_t n
   if (dust_policy.dust_threshold > 0)
     money_back = money_back - money_back % dust_policy.dust_threshold;
   dsts.push_back(cryptonote::tx_destination_entry(money_back, m_account_public_address));
-  uint64_t dust = 0;
-  std::vector<cryptonote::tx_destination_entry> splitted_dsts;
+  std::vector<cryptonote::tx_destination_entry> splitted_dsts, dust;
   destination_split_strategy(dsts, change_dts, dust_policy.dust_threshold, splitted_dsts, dust);
-  THROW_WALLET_EXCEPTION_IF(dust_policy.dust_threshold < dust, error::wallet_internal_error, "invalid dust value: dust = " +
-    std::to_string(dust) + ", dust_threshold = " + std::to_string(dust_policy.dust_threshold));
+  BOOST_FOREACH(auto& d, dust) {
+    THROW_WALLET_EXCEPTION_IF(dust_policy.dust_threshold < d.amount, error::wallet_internal_error, "invalid dust value: dust = " +
+      std::to_string(d.amount) + ", dust_threshold = " + std::to_string(dust_policy.dust_threshold));
+  }
 
   crypto::secret_key tx_key;
   bool r = cryptonote::construct_tx_and_get_tx_key(m_account.get_keys(), sources, splitted_dsts, extra, tx, unlock_time, tx_key);
@@ -1945,7 +1949,7 @@ void wallet2::transfer_dust(size_t num_outputs, uint64_t unlock_time, uint64_t n
 
   ptx.key_images = key_images;
   ptx.fee = money - money_back;
-  ptx.dust = dust;
+  ptx.dust = 0;
   ptx.tx = tx;
   ptx.change_dts = change_dts;
   ptx.selected_transfers = selected_transfers;
@@ -1961,7 +1965,7 @@ std::vector<wallet2::pending_tx> wallet2::create_dust_sweep_transactions()
   for (transfer_container::const_iterator i = m_transfers.begin(); i != m_transfers.end(); ++i)
   {
     const transfer_details& td = *i;
-    if (!td.m_spent && td.amount() < dust_policy.dust_threshold && is_transfer_unlocked(td))
+    if (!td.m_spent && (td.amount() < dust_policy.dust_threshold || !is_valid_decomposed_amount(td.amount())) && is_transfer_unlocked(td))
     {
       num_dust_outputs++;
     }
diff --git a/src/wallet/wallet2.h b/src/wallet/wallet2.h
index b086f7ee8..0bffa7f12 100644
--- a/src/wallet/wallet2.h
+++ b/src/wallet/wallet2.h
@@ -400,48 +400,36 @@ namespace tools
     //----------------------------------------------------------------------------------------------------
     inline void digit_split_strategy(const std::vector<cryptonote::tx_destination_entry>& dsts,
       const cryptonote::tx_destination_entry& change_dst, uint64_t dust_threshold,
-      std::vector<cryptonote::tx_destination_entry>& splitted_dsts, uint64_t& dust)
+      std::vector<cryptonote::tx_destination_entry>& splitted_dsts, std::vector<cryptonote::tx_destination_entry> &dust_dsts)
     {
       splitted_dsts.clear();
-      dust = 0;
+      dust_dsts.clear();
 
       BOOST_FOREACH(auto& de, dsts)
       {
-        cryptonote::decompose_amount_into_digits(de.amount, dust_threshold,
+        cryptonote::decompose_amount_into_digits(de.amount, 0,
           [&](uint64_t chunk) { splitted_dsts.push_back(cryptonote::tx_destination_entry(chunk, de.addr)); },
           [&](uint64_t a_dust) { splitted_dsts.push_back(cryptonote::tx_destination_entry(a_dust, de.addr)); } );
       }
 
-      cryptonote::decompose_amount_into_digits(change_dst.amount, dust_threshold,
-        [&](uint64_t chunk) { splitted_dsts.push_back(cryptonote::tx_destination_entry(chunk, change_dst.addr)); },
-        [&](uint64_t a_dust) { dust = a_dust; } );
+      cryptonote::decompose_amount_into_digits(change_dst.amount, 0,
+        [&](uint64_t chunk) {
+          if (chunk <= dust_threshold)
+            dust_dsts.push_back(cryptonote::tx_destination_entry(chunk, change_dst.addr));
+          else
+            splitted_dsts.push_back(cryptonote::tx_destination_entry(chunk, change_dst.addr));
+        },
+        [&](uint64_t a_dust) { dust_dsts.push_back(cryptonote::tx_destination_entry(a_dust, change_dst.addr)); } );
     }
     //----------------------------------------------------------------------------------------------------
     inline void null_split_strategy(const std::vector<cryptonote::tx_destination_entry>& dsts,
       const cryptonote::tx_destination_entry& change_dst, uint64_t dust_threshold,
-      std::vector<cryptonote::tx_destination_entry>& splitted_dsts, uint64_t& dust)
+      std::vector<cryptonote::tx_destination_entry>& splitted_dsts, std::vector<cryptonote::tx_destination_entry> &dust_dsts)
     {
       splitted_dsts = dsts;
 
-      dust = 0;
+      dust_dsts.clear();
       uint64_t change = change_dst.amount;
-      if (0 < dust_threshold)
-      {
-        for (uint64_t order = 10; order <= 10 * dust_threshold; order *= 10)
-        {
-          uint64_t dust_candidate = change_dst.amount % order;
-          uint64_t change_candidate = (change_dst.amount / order) * order;
-          if (dust_candidate <= dust_threshold)
-          {
-            dust = dust_candidate;
-            change = change_candidate;
-          }
-          else
-          {
-            break;
-          }
-        }
-      }
 
       if (0 != change)
       {
@@ -577,14 +565,17 @@ namespace tools
       change_dts.amount = found_money - needed_money;
     }
 
+    std::vector<cryptonote::tx_destination_entry> splitted_dsts, dust_dsts;
     uint64_t dust = 0;
-    std::vector<cryptonote::tx_destination_entry> splitted_dsts;
-    destination_split_strategy(dsts, change_dts, dust_policy.dust_threshold, splitted_dsts, dust);
-    THROW_WALLET_EXCEPTION_IF(dust_policy.dust_threshold < dust, error::wallet_internal_error, "invalid dust value: dust = " +
-      std::to_string(dust) + ", dust_threshold = " + std::to_string(dust_policy.dust_threshold));
-    if (0 != dust && !dust_policy.add_to_fee)
-    {
-      splitted_dsts.push_back(cryptonote::tx_destination_entry(dust, dust_policy.addr_for_dust));
+    destination_split_strategy(dsts, change_dts, dust_policy.dust_threshold, splitted_dsts, dust_dsts);
+    BOOST_FOREACH(auto& d, dust_dsts) {
+      THROW_WALLET_EXCEPTION_IF(dust_policy.dust_threshold < d.amount, error::wallet_internal_error, "invalid dust value: dust = " +
+        std::to_string(d.amount) + ", dust_threshold = " + std::to_string(dust_policy.dust_threshold));
+    }
+    BOOST_FOREACH(auto& d, dust_dsts) {
+      if (!dust_policy.add_to_fee)
+        splitted_dsts.push_back(cryptonote::tx_destination_entry(d.amount, dust_policy.addr_for_dust));
+      dust += d.amount;
     }
 
     crypto::secret_key tx_key;