Add the possibility to export private view key for fast scan.

On client startup the device asks for authorization to export the private view key.
If user agree, the client hold the private view key allowing a fast blockchain scan.
If the user does not agree, the blockchain scan is fully done via the device.

1 files changed, 117 insertions, 54 deletions

diff --git a/src/device/device_ledger.cpp b/src/device/device_ledger.cpp
index 30ecb67bb..ee1497438 100644
--- a/src/device/device_ledger.cpp
+++ b/src/device/device_ledger.cpp
@@ -58,8 +58,8 @@ namespace hw {
     #define ASSERT_T0(exp)       CHECK_AND_ASSERT_THROW_MES(exp, "Protocol assert failure: "#exp ) ;
 
     #ifdef DEBUG_HWDEVICE
-      crypto::secret_key viewkey;
-      crypto::secret_key spendkey;
+      crypto::secret_key dbg_viewkey;
+      crypto::secret_key dbg_spendkey;
     #endif
 
     /* ===================================================================== */
@@ -119,7 +119,14 @@ namespace hw {
     #endif
 
     /* ===================================================================== */
-    /* ===                         Device                               ==== */
+    /* ===                       Internal Helpers                       ==== */
+    /* ===================================================================== */
+    static bool is_fake_view_key(const crypto::secret_key &sec) {
+      return sec == crypto::null_skey;
+    }
+
+    /* ===================================================================== */
+    /* ===                             Device                           ==== */
     /* ===================================================================== */
 
     static int device_id = 0;
@@ -197,6 +204,8 @@ namespace hw {
       this->hCard   = 0;
       this->hContext = 0;
       this->reset_buffer();      
+      this->mode = NONE;
+      this->has_view_key = false;
       MDEBUG( "Device "<<this->id <<" Created");
     }
 
@@ -403,10 +412,10 @@ namespace hw {
       #ifdef DEBUG_HWDEVICE
       cryptonote::account_public_address pubkey;
       this->get_public_address(pubkey);
+      #endif
       crypto::secret_key vkey;
       crypto::secret_key skey;
       this->get_secret_keys(vkey,skey);
-      #endif
 
       return rv==SCARD_S_SUCCESS;
     }
@@ -420,6 +429,47 @@ namespace hw {
       return true;
     }
 
+    bool  device_ledger::set_mode(device_mode mode) {
+        AUTO_LOCK_CMD();
+
+        int offset;
+
+        reset_buffer();
+
+        switch(mode) {
+        case TRANSACTION_CREATE_REAL:
+        case TRANSACTION_CREATE_FAKE:
+          this->buffer_send[0] = 0x00;
+          this->buffer_send[1] = INS_SET_SIGNATURE_MODE;
+          this->buffer_send[2] = 0x01;
+          this->buffer_send[3] = 0x00;
+          this->buffer_send[4] = 0x00;
+          offset = 5;
+          //options
+          this->buffer_send[offset] = 0x00;
+          offset += 1;
+          //account
+          this->buffer_send[offset] = mode;
+          offset += 1;
+
+          this->buffer_send[4] = offset-5;
+          this->length_send = offset;
+          this->exchange();
+
+          this->mode = mode;
+          break;
+
+        case TRANSACTION_PARSE: 
+        case NONE:
+          this->mode = mode;
+          break;
+        default:
+           CHECK_AND_ASSERT_THROW_MES(false, " device_ledger::set_mode(unsigned int mode): invalid mode: "<<mode);
+        }
+        MDEBUG("Switch to mode: " <<mode);
+        return true;
+    }
+
 
     /* ======================================================================= */
     /*                             WALLET & ADDRESS                            */
@@ -451,12 +501,13 @@ namespace hw {
         return true;
     }
 
-    bool  device_ledger::get_secret_keys(crypto::secret_key &viewkey , crypto::secret_key &spendkey) {
+    bool  device_ledger::get_secret_keys(crypto::secret_key &vkey , crypto::secret_key &skey) {
         AUTO_LOCK_CMD();
-      memset(viewkey.data, 0x00, 32);
-      memset(spendkey.data, 0xFF, 32);
 
-      #ifdef DEBUG_HWDEVICE
+        //secret key are represented as fake key on the wallet side
+        memset(vkey.data, 0x00, 32);
+        memset(skey.data, 0xFF, 32);
+
         //spcialkey, normal conf handled in decrypt
         int offset;
         reset_buffer();
@@ -475,12 +526,22 @@ namespace hw {
         this->length_send = offset;
         this->exchange();
 
-        //clear key
-        memmove(ledger::viewkey.data,  this->buffer_recv+64, 32);
-        memmove(ledger::spendkey.data, this->buffer_recv+96, 32);
+        //View key is retrievied, if allowed, to speed up blockchain parsing
+        memmove(this->viewkey.data,  this->buffer_recv+0,  32);
+        if (is_fake_view_key(this->viewkey)) {
+          MDEBUG("Have Not view key");
+          this->has_view_key = false;
+        } else {
+          MDEBUG("Have view key");
+          this->has_view_key = true;
+        }
+      
+        #ifdef DEBUG_HWDEVICE
+        memmove(dbg_viewkey.data, this->buffer_recv+0, 32);
+        memmove(dbg_spendkey.data, this->buffer_recv+32, 32);
+        #endif
 
-      #endif
-      return true;
+        return true;
     }
 
     bool  device_ledger::generate_chacha_key(const cryptonote::account_keys &keys, crypto::chacha_key &key) {
@@ -525,11 +586,14 @@ namespace hw {
 
     bool device_ledger::derive_subaddress_public_key(const crypto::public_key &pub, const crypto::key_derivation &derivation, const std::size_t output_index, crypto::public_key &derived_pub){
         AUTO_LOCK_CMD();
-        int offset;
-
         #ifdef DEBUG_HWDEVICE
         const crypto::public_key pub_x = pub;
-        const crypto::key_derivation derivation_x  = hw::ledger::decrypt(derivation);
+        crypto::key_derivation derivation_x;
+         if ((this->mode == TRANSACTION_PARSE) && has_view_key) {    
+          derivation_x = derivation;
+        } else {
+          derivation_x = hw::ledger::decrypt(derivation);
+        }
         const std::size_t output_index_x = output_index;
         crypto::public_key derived_pub_x;
         hw::ledger::log_hexbuffer("derive_subaddress_public_key: [[IN]]  pub       ", pub_x.data, 32);
@@ -539,6 +603,15 @@ namespace hw {
         hw::ledger::log_hexbuffer("derive_subaddress_public_key: [[OUT]] derived_pub", derived_pub_x.data, 32);
         #endif
 
+      if ((this->mode == TRANSACTION_PARSE) && has_view_key) {     
+        //If we are in TRANSACTION_PARSE, the given derivation has been retrieved uncrypted (wihtout the help
+        //of the device), so continue that way.
+        MDEBUG( "derive_subaddress_public_key  : PARSE mode with known viewkey");     
+        crypto::derive_subaddress_public_key(pub, derivation, output_index,derived_pub);
+      } else {
+       
+        int offset =0;
+ 
         reset_buffer();
 
         this->buffer_send[0] = 0x00;
@@ -569,10 +642,10 @@ namespace hw {
 
         //pub key
         memmove(derived_pub.data, &this->buffer_recv[0], 32);
-
-        #ifdef DEBUG_HWDEVICE
-        hw::ledger::check32("derive_subaddress_public_key", "derived_pub", derived_pub_x.data, derived_pub.data);
-        #endif
+      }
+      #ifdef DEBUG_HWDEVICE
+      hw::ledger::check32("derive_subaddress_public_key", "derived_pub", derived_pub_x.data, derived_pub.data);
+      #endif
 
       return true;
     }
@@ -959,7 +1032,7 @@ namespace hw {
 
     bool device_ledger::generate_key_derivation(const crypto::public_key &pub, const crypto::secret_key &sec, crypto::key_derivation &derivation) {
         AUTO_LOCK_CMD();
-        int offset;
+        bool r = false;
 
         #ifdef DEBUG_HWDEVICE
         const crypto::public_key pub_x = pub;
@@ -971,6 +1044,17 @@ namespace hw {
         hw::ledger::log_hexbuffer("generate_key_derivation: [[OUT]] derivation", derivation_x.data, 32);
         #endif
 
+      if ((this->mode == TRANSACTION_PARSE)  && has_view_key) {
+        //A derivation is resquested in PASRE mode and we have the view key,
+        //so do that wihtout the device and return the derivation unencrypted.
+        MDEBUG( "generate_key_derivation  : PARSE mode with known viewkey");     
+        //Note derivation in PARSE mode can only happen with viewkey, so assert it!
+        assert(is_fake_view_key(sec));
+        r = crypto::generate_key_derivation(pub, this->viewkey, derivation);
+      } else {
+
+        int offset;
+
         reset_buffer();
 
         this->buffer_send[0] = 0x00;
@@ -995,14 +1079,19 @@ namespace hw {
 
         //derivattion data
         memmove(derivation.data, &this->buffer_recv[0], 32);
+        r = true;
+      }
+      #ifdef DEBUG_HWDEVICE
+      crypto::key_derivation derivation_clear ;
+        if ((this->mode == TRANSACTION_PARSE)  && has_view_key) {
+          derivation_clear  = derivation;
+        }else {
+          derivation_clear  = hw::ledger::decrypt(derivation);
+        }
+      hw::ledger::check32("generate_key_derivation", "derivation", derivation_x.data, derivation_clear.data);
+      #endif
 
-        #ifdef DEBUG_HWDEVICE
-        crypto::key_derivation derivation_clear  = hw::ledger::decrypt(derivation);
-        hw::ledger::check32("generate_key_derivation", "derivation", derivation_x.data, derivation_clear.data);
-        #endif
-
-
-      return true;
+      return r;
     }
 
     bool device_ledger::derivation_to_scalar(const crypto::key_derivation &derivation, const size_t output_index, crypto::ec_scalar &res) {
@@ -1290,32 +1379,6 @@ namespace hw {
         return true;
     }
 
-    bool  device_ledger::set_signature_mode(unsigned int sig_mode) {
-        AUTO_LOCK_CMD();
-        int offset ;
-
-        reset_buffer();
-
-        this->buffer_send[0] = 0x00;
-        this->buffer_send[1] = INS_SET_SIGNATURE_MODE;
-        this->buffer_send[2] = 0x01;
-        this->buffer_send[3] = 0x00;
-        this->buffer_send[4] = 0x00;
-        offset = 5;
-        //options
-        this->buffer_send[offset] = 0x00;
-        offset += 1;
-        //account
-        this->buffer_send[offset] = sig_mode;
-        offset += 1;
-
-        this->buffer_send[4] = offset-5;
-        this->length_send = offset;
-        this->exchange();
-        
-      return true;
-    }
-
     bool device_ledger::encrypt_payment_id(crypto::hash8 &payment_id, const crypto::public_key &public_key, const crypto::secret_key &secret_key) {
         AUTO_LOCK_CMD();
         int offset;