ringct: do not serialize what can be reconstructed

The mixRing (output keys and commitments) and II fields (key images)
can be reconstructed from vin data.
This saves some modest amount of space in the tx.

1 files changed, 8 insertions, 5 deletions

diff --git a/src/wallet/wallet2.cpp b/src/wallet/wallet2.cpp
index 59472e648..3565945d4 100644
--- a/src/wallet/wallet2.cpp
+++ b/src/wallet/wallet2.cpp
@@ -3237,16 +3237,19 @@ static size_t estimate_rct_tx_size(int n_inputs, int mixin, int n_outputs)
 
   // rangeSigs
   size += (2*64*32+32+64*32) * n_outputs;
-  // MG
-  size += 32 * (mixin+1) * n_inputs + 32 + 32 * n_inputs;
-  // mixRing
-  size += 2 * 32 * (mixin+1) * n_inputs;
+
+  // MG - only the last slot of II is saved, the rest can be reconstructed
+  size += 32 * (mixin+1) * n_inputs + 32 + 32 * (/*n_inputs+*/1) ;
+
+  // mixRing - not serialized, can be reconstructed
+  /* size += 2 * 32 * (mixin+1) * n_inputs; */
+
   // ecdhInfo
   size += 3 * 32 * n_outputs;
   // outPk
   size += 2 * 32 * n_outputs;
 
-  LOG_PRINT_L2("estimated rct tx size for " << n_inputs << " at mixin " << mixin << " and " << n_outputs << ": " << size);
+  LOG_PRINT_L2("estimated rct tx size for " << n_inputs << " at mixin " << mixin << " and " << n_outputs << ": " << size << " (" << (32 * n_inputs + 2 * 32 * (mixin+1) * n_inputs) << " saved)");
   return size;
 }