store outPk/8 in the tx for speed

It avoids dividing by 8 when deserializing a tx, which is a slow
operation, and multiplies by 8 when verifying and extracing the
amount, which is much faster as well as less frequent

1 files changed, 17 insertions, 4 deletions

diff --git a/src/ringct/rctSigs.cpp b/src/ringct/rctSigs.cpp
index 961d83a9e..d7883baac 100644
--- a/src/ringct/rctSigs.cpp
+++ b/src/ringct/rctSigs.cpp
@@ -1205,7 +1205,7 @@ namespace rct {
         rv.p.bulletproofs_plus.clear();
         if (bulletproof_or_plus)
         {
-            const bool plus = rv.type == RCTTypeBulletproofPlus;
+            const bool plus = is_rct_bulletproof_plus(rv.type);
             size_t n_amounts = outamounts.size();
             size_t amounts_proved = 0;
             if (rct_config.range_proof_type == RangeProofPaddedBulletproof)
@@ -1235,7 +1235,10 @@ namespace rct {
                 }
                 for (i = 0; i < outamounts.size(); ++i)
                 {
-                    rv.outPk[i].mask = rct::scalarmult8(C[i]);
+                    if (plus)
+                      rv.outPk[i].mask = C[i];
+                    else
+                      rv.outPk[i].mask = rct::scalarmult8(C[i]);
                     outSk[i].mask = masks[i];
                 }
             }
@@ -1273,7 +1276,10 @@ namespace rct {
                 }
                 for (i = 0; i < batch_size; ++i)
                 {
-                  rv.outPk[i + amounts_proved].mask = rct::scalarmult8(C[i]);
+                  if (plus)
+                    rv.outPk[i + amounts_proved].mask = C[i];
+                  else
+                    rv.outPk[i + amounts_proved].mask = rct::scalarmult8(C[i]);
                   outSk[i + amounts_proved].mask = masks[i];
                 }
                 amounts_proved += batch_size;
@@ -1480,7 +1486,10 @@ namespace rct {
 
           rct::keyV masks(rv.outPk.size());
           for (size_t i = 0; i < rv.outPk.size(); i++) {
-            masks[i] = rv.outPk[i].mask;
+            if (bulletproof_plus)
+              masks[i] = rct::scalarmult8(rv.outPk[i].mask);
+            else
+              masks[i] = rv.outPk[i].mask;
           }
           key sumOutpks = addKeys(masks);
           DP(sumOutpks);
@@ -1640,6 +1649,8 @@ namespace rct {
         mask = ecdh_info.mask;
         key amount = ecdh_info.amount;
         key C = rv.outPk[i].mask;
+        if (is_rct_bulletproof_plus(rv.type))
+          C = scalarmult8(C);
         DP("C");
         DP(C);
         key Ctmp;
@@ -1671,6 +1682,8 @@ namespace rct {
         mask = ecdh_info.mask;
         key amount = ecdh_info.amount;
         key C = rv.outPk[i].mask;
+        if (is_rct_bulletproof_plus(rv.type))
+          C = scalarmult8(C);
         DP("C");
         DP(C);
         key Ctmp;