Add view tags to outputs to reduce wallet scanning time

Implements view tags as proposed by @UkoeHB in MRL issue
https://github.com/monero-project/research-lab/issues/73

At tx construction, the sender adds a 1-byte view tag to each
output. The view tag is derived from the sender-receiver
shared secret. When scanning for outputs, the receiver can
check the view tag for a match, in order to reduce scanning
time. When the view tag does not match, the wallet avoids the
more expensive EC operations when deriving the output public
key using the shared secret.

1 files changed, 10 insertions, 4 deletions

diff --git a/src/cryptonote_core/cryptonote_core.cpp b/src/cryptonote_core/cryptonote_core.cpp
index 2d2b1cbcf..a78f5d673 100644
--- a/src/cryptonote_core/cryptonote_core.cpp
+++ b/src/cryptonote_core/cryptonote_core.cpp
@@ -1177,7 +1177,8 @@ namespace cryptonote
       return false;
     }
 
-    if (!check_tx_inputs_ring_members_diff(tx))
+    const uint8_t hf_version = m_blockchain_storage.get_current_hard_fork_version();
+    if (!check_tx_inputs_ring_members_diff(tx, hf_version))
     {
       MERROR_VER("tx uses duplicate ring members");
       return false;
@@ -1189,6 +1190,12 @@ namespace cryptonote
       return false;
     }
 
+    if (!check_output_types(tx, hf_version))
+    {
+      MERROR_VER("tx does not use valid output type(s)");
+      return false;
+    }
+
     return true;
   }
   //-----------------------------------------------------------------------------------------------
@@ -1295,10 +1302,9 @@ namespace cryptonote
     return true;
   }
   //-----------------------------------------------------------------------------------------------
-  bool core::check_tx_inputs_ring_members_diff(const transaction& tx) const
+  bool core::check_tx_inputs_ring_members_diff(const transaction& tx, const uint8_t hf_version) const
   {
-    const uint8_t version = m_blockchain_storage.get_current_hard_fork_version();
-    if (version >= 6)
+    if (hf_version >= 6)
     {
       for(const auto& in: tx.vin)
       {