diff --git a/src/device/device.hpp b/src/device/device.hpp
index db489ff0c..9df0cb39d 100644
--- a/src/device/device.hpp
+++ b/src/device/device.hpp
@@ -145,6 +145,7 @@ namespace hw {
         virtual bool  sc_secret_add( crypto::secret_key &r, const crypto::secret_key &a, const crypto::secret_key &b) = 0;
         virtual crypto::secret_key  generate_keys(crypto::public_key &pub, crypto::secret_key &sec, const crypto::secret_key& recovery_key = crypto::secret_key(), bool recover = false) = 0;
         virtual bool  generate_key_derivation(const crypto::public_key &pub, const crypto::secret_key &sec, crypto::key_derivation &derivation) = 0;
+        virtual bool  conceal_derivation(crypto::key_derivation &derivation, const crypto::public_key &tx_pub_key, const std::vector<crypto::public_key> &additional_tx_pub_keys, const crypto::key_derivation &main_derivation, const std::vector<crypto::key_derivation> &additional_derivations) = 0;
         virtual bool  derivation_to_scalar(const crypto::key_derivation &derivation, const size_t output_index, crypto::ec_scalar &res) = 0;
         virtual bool  derive_secret_key(const crypto::key_derivation &derivation, const std::size_t output_index, const crypto::secret_key &sec,  crypto::secret_key &derived_sec) = 0;
         virtual bool  derive_public_key(const crypto::key_derivation &derivation, const std::size_t output_index, const crypto::public_key &pub,  crypto::public_key &derived_pub) = 0;
diff --git a/src/device/device_default.cpp b/src/device/device_default.cpp
index 56bd1e164..0071f7d4f 100644
--- a/src/device/device_default.cpp
+++ b/src/device/device_default.cpp
@@ -264,6 +264,10 @@ namespace hw {
             return true;
         }
 
+        bool device_default::conceal_derivation(crypto::key_derivation &derivation, const crypto::public_key &tx_pub_key, const std::vector<crypto::public_key> &additional_tx_pub_keys, const crypto::key_derivation &main_derivation, const std::vector<crypto::key_derivation> &additional_derivations){
+            return true;
+        }
+
         /* ======================================================================= */
         /*                               TRANSACTION                               */
         /* ======================================================================= */
diff --git a/src/device/device_default.hpp b/src/device/device_default.hpp
index 53942f53a..649fed862 100644
--- a/src/device/device_default.hpp
+++ b/src/device/device_default.hpp
@@ -93,6 +93,7 @@ namespace hw {
             bool  sc_secret_add(crypto::secret_key &r, const crypto::secret_key &a, const crypto::secret_key &b) override;
             crypto::secret_key  generate_keys(crypto::public_key &pub, crypto::secret_key &sec, const crypto::secret_key& recovery_key = crypto::secret_key(), bool recover = false) override;
             bool  generate_key_derivation(const crypto::public_key &pub, const crypto::secret_key &sec, crypto::key_derivation &derivation) override;
+            bool  conceal_derivation(crypto::key_derivation &derivation, const crypto::public_key &tx_pub_key, const std::vector<crypto::public_key> &additional_tx_pub_keys, const crypto::key_derivation &main_derivation, const std::vector<crypto::key_derivation> &additional_derivations);
             bool  derivation_to_scalar(const crypto::key_derivation &derivation, const size_t output_index, crypto::ec_scalar &res) override;
             bool  derive_secret_key(const crypto::key_derivation &derivation, const std::size_t output_index, const crypto::secret_key &sec,  crypto::secret_key &derived_sec) override;
             bool  derive_public_key(const crypto::key_derivation &derivation, const std::size_t output_index, const crypto::public_key &pub,  crypto::public_key &derived_pub) override;
diff --git a/src/device/device_ledger.cpp b/src/device/device_ledger.cpp
index ee1497438..3b9ab6744 100644
--- a/src/device/device_ledger.cpp
+++ b/src/device/device_ledger.cpp
@@ -56,6 +56,7 @@ namespace hw {
     #define ASSERT_RV(rv)        CHECK_AND_ASSERT_THROW_MES((rv)==SCARD_S_SUCCESS, "Fail SCard API : (" << (rv) << ") "<< pcsc_stringify_error(rv)<<" Device="<<this->id<<", hCard="<<hCard<<", hContext="<<hContext);
     #define ASSERT_SW(sw,ok,msk) CHECK_AND_ASSERT_THROW_MES(((sw)&(mask))==(ok), "Wrong Device Status : SW=" << std::hex << (sw) << " (EXPECT=" << std::hex << (ok) << ", MASK=" << std::hex << (mask) << ")") ;
     #define ASSERT_T0(exp)       CHECK_AND_ASSERT_THROW_MES(exp, "Protocol assert failure: "#exp ) ;
+    #define ASSERT_X(exp,msg)    CHECK_AND_ASSERT_THROW_MES(exp, msg); 
 
     #ifdef DEBUG_HWDEVICE
       crypto::secret_key dbg_viewkey;
@@ -125,6 +126,10 @@ namespace hw {
       return sec == crypto::null_skey;
     }
 
+    bool operator==(const crypto::key_derivation &d0, const crypto::key_derivation &d1) {
+      return !memcmp(&d0, &d1, sizeof(d0));
+    }
+
     /* ===================================================================== */
     /* ===                             Device                           ==== */
     /* ===================================================================== */
@@ -1094,6 +1099,24 @@ namespace hw {
       return r;
     }
 
+    bool device_ledger::conceal_derivation(crypto::key_derivation &derivation, const crypto::public_key &tx_pub_key, const std::vector<crypto::public_key> &additional_tx_pub_keys, const crypto::key_derivation &main_derivation, const std::vector<crypto::key_derivation> &additional_derivations) {
+      const crypto::public_key *pkey=NULL;
+      if (derivation == main_derivation) {        
+        pkey = &tx_pub_key;
+        MDEBUG("conceal derivation with main tx pub key");
+      } else {
+        for(size_t n=0; n < additional_derivations.size();++n) {
+          if(derivation == additional_derivations[n]) {
+            pkey = &additional_tx_pub_keys[n];
+            MDEBUG("conceal derivation with additionnal tx pub key");
+            break;
+          }
+        }
+      }
+      ASSERT_X(pkey, "Mismatched derivation on scan info");
+      return this->generate_key_derivation(*pkey,  crypto::null_skey, derivation);
+    } 
+
     bool device_ledger::derivation_to_scalar(const crypto::key_derivation &derivation, const size_t output_index, crypto::ec_scalar &res) {
         AUTO_LOCK_CMD();
         int offset;
diff --git a/src/device/device_ledger.hpp b/src/device/device_ledger.hpp
index 652cfb34b..9f73bd070 100644
--- a/src/device/device_ledger.hpp
+++ b/src/device/device_ledger.hpp
@@ -169,6 +169,7 @@ namespace hw {
         bool  sc_secret_add(crypto::secret_key &r, const crypto::secret_key &a, const crypto::secret_key &b) override;
         crypto::secret_key  generate_keys(crypto::public_key &pub, crypto::secret_key &sec, const crypto::secret_key& recovery_key = crypto::secret_key(), bool recover = false) override;
         bool  generate_key_derivation(const crypto::public_key &pub, const crypto::secret_key &sec, crypto::key_derivation &derivation) override;
+        bool  conceal_derivation(crypto::key_derivation &derivation, const crypto::public_key &tx_pub_key, const std::vector<crypto::public_key> &additional_tx_pub_keys, const crypto::key_derivation &main_derivation, const std::vector<crypto::key_derivation> &additional_derivations);
         bool  derivation_to_scalar(const crypto::key_derivation &derivation, const size_t output_index, crypto::ec_scalar &res) override;
         bool  derive_secret_key(const crypto::key_derivation &derivation, const std::size_t output_index, const crypto::secret_key &sec,  crypto::secret_key &derived_sec) override;
         bool  derive_public_key(const crypto::key_derivation &derivation, const std::size_t output_index, const crypto::public_key &pub,  crypto::public_key &derived_pub) override;
diff --git a/src/wallet/wallet2.cpp b/src/wallet/wallet2.cpp
index b06444132..8a1d29143 100644
--- a/src/wallet/wallet2.cpp
+++ b/src/wallet/wallet2.cpp
@@ -1008,7 +1008,7 @@ void wallet2::set_unspent(size_t idx)
 void wallet2::check_acc_out_precomp(const tx_out &o, const crypto::key_derivation &derivation, const std::vector<crypto::key_derivation> &additional_derivations, size_t i, tx_scan_info_t &tx_scan_info) const
 {
   hw::device &hwdev = m_account.get_device();
-  std::unique_lock<hw::device> hwdev_lock (hwdev);
+  boost::unique_lock<hw::device> hwdev_lock (hwdev);
   hwdev.set_mode(hw::device::TRANSACTION_PARSE);
   if (o.target.type() !=  typeid(txout_to_key))
   {
@@ -1086,7 +1086,7 @@ void wallet2::process_new_transaction(const crypto::hash &txid, const cryptonote
   //ensure device is let in NONE mode in any case
   hw::device &hwdev = m_account.get_device(); 
   
-  std::unique_lock<hw::device> hwdev_lock (hwdev);
+  boost::unique_lock<hw::device> hwdev_lock (hwdev);
   hw::reset_mode rst(hwdev);  
   hwdev_lock.unlock();
 
@@ -1181,7 +1181,7 @@ void wallet2::process_new_transaction(const crypto::hash &txid, const cryptonote
           THROW_WALLET_EXCEPTION_IF(tx_scan_info[i].error, error::acc_outs_lookup_error, tx, tx_pub_key, m_account.get_keys());
           if (tx_scan_info[i].received)
           {
-            hwdev.generate_key_derivation(tx_pub_key,  keys.m_view_secret_key, tx_scan_info[i].received->derivation);
+            hwdev.conceal_derivation(tx_scan_info[i].received->derivation, tx_pub_key, additional_tx_pub_keys, derivation, additional_derivations);
             scan_output(tx, tx_pub_key, i, tx_scan_info[i], num_vouts_received, tx_money_got_in_outs, outs);
           }
         }
@@ -1204,7 +1204,7 @@ void wallet2::process_new_transaction(const crypto::hash &txid, const cryptonote
         THROW_WALLET_EXCEPTION_IF(tx_scan_info[i].error, error::acc_outs_lookup_error, tx, tx_pub_key, m_account.get_keys());
         if (tx_scan_info[i].received)
         {
-          hwdev.generate_key_derivation(tx_pub_key,  keys.m_view_secret_key, tx_scan_info[i].received->derivation);
+          hwdev.conceal_derivation(tx_scan_info[i].received->derivation, tx_pub_key, additional_tx_pub_keys, derivation, additional_derivations);
           scan_output(tx, tx_pub_key, i, tx_scan_info[i], num_vouts_received, tx_money_got_in_outs, outs);
         }
       }
@@ -1220,7 +1220,7 @@ void wallet2::process_new_transaction(const crypto::hash &txid, const cryptonote
         {
           hwdev_lock.lock();
           hwdev.set_mode(hw::device::NONE);
-          hwdev.generate_key_derivation(tx_pub_key,  keys.m_view_secret_key, tx_scan_info[i].received->derivation);
+          hwdev.conceal_derivation(tx_scan_info[i].received->derivation, tx_pub_key, additional_tx_pub_keys, derivation, additional_derivations);
           scan_output(tx, tx_pub_key, i, tx_scan_info[i], num_vouts_received, tx_money_got_in_outs, outs);
           hwdev_lock.unlock();
         }
@@ -7285,7 +7285,7 @@ std::vector<wallet2::pending_tx> wallet2::create_transactions_2(std::vector<cryp
 {
   //ensure device is let in NONE mode in any case
   hw::device &hwdev = m_account.get_device();
-  std::unique_lock<hw::device> hwdev_lock (hwdev);
+  boost::unique_lock<hw::device> hwdev_lock (hwdev);
   hw::reset_mode rst(hwdev);  
 
   if(m_light_wallet) {
@@ -7868,7 +7868,7 @@ std::vector<wallet2::pending_tx> wallet2::create_transactions_from(const crypton
 {
   //ensure device is let in NONE mode in any case
   hw::device &hwdev = m_account.get_device();
-  std::unique_lock<hw::device> hwdev_lock (hwdev);
+  boost::unique_lock<hw::device> hwdev_lock (hwdev);
   hw::reset_mode rst(hwdev);  
 
   uint64_t accumulated_fee, accumulated_outputs, accumulated_change;