From ada4291469156f76eb605b2110a068df58a4e142 Mon Sep 17 00:00:00 2001
From: moneromooo-monero <moneromooo-monero@users.noreply.github.com>
Date: Tue, 21 Nov 2017 22:55:57 +0000
Subject: [PATCH] add a version of ge_double_scalarmult_precomp_vartime with A
 precomp

---
 src/crypto/crypto-ops.c | 11 ++++++++---
 src/crypto/crypto-ops.h |  1 +
 src/ringct/rctOps.cpp   |  9 +++++++++
 src/ringct/rctOps.h     |  1 +
 4 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/src/crypto/crypto-ops.c b/src/crypto/crypto-ops.c
index 1e4969558..b5c62bce4 100644
--- a/src/crypto/crypto-ops.c
+++ b/src/crypto/crypto-ops.c
@@ -2000,17 +2000,15 @@ void ge_scalarmult(ge_p2 *r, const unsigned char *a, const ge_p3 *A) {
   }
 }
 
-void ge_double_scalarmult_precomp_vartime(ge_p2 *r, const unsigned char *a, const ge_p3 *A, const unsigned char *b, const ge_dsmp Bi) {
+void ge_double_scalarmult_precomp_vartime2(ge_p2 *r, const unsigned char *a, const ge_dsmp Ai, const unsigned char *b, const ge_dsmp Bi) {
   signed char aslide[256];
   signed char bslide[256];
-  ge_dsmp Ai; /* A, 3A, 5A, 7A, 9A, 11A, 13A, 15A */
   ge_p1p1 t;
   ge_p3 u;
   int i;
 
   slide(aslide, a);
   slide(bslide, b);
-  ge_dsm_precomp(Ai, A);
 
   ge_p2_0(r);
 
@@ -2041,6 +2039,13 @@ void ge_double_scalarmult_precomp_vartime(ge_p2 *r, const unsigned char *a, cons
   }
 }
 
+void ge_double_scalarmult_precomp_vartime(ge_p2 *r, const unsigned char *a, const ge_p3 *A, const unsigned char *b, const ge_dsmp Bi) {
+  ge_dsmp Ai; /* A, 3A, 5A, 7A, 9A, 11A, 13A, 15A */
+
+  ge_dsm_precomp(Ai, A);
+  ge_double_scalarmult_precomp_vartime2(r, a, Ai, b, Bi);
+}
+
 void ge_mul8(ge_p1p1 *r, const ge_p2 *t) {
   ge_p2 u;
   ge_p2_dbl(r, t);
diff --git a/src/crypto/crypto-ops.h b/src/crypto/crypto-ops.h
index 5091de1f6..c76455551 100644
--- a/src/crypto/crypto-ops.h
+++ b/src/crypto/crypto-ops.h
@@ -128,6 +128,7 @@ void sc_reduce(unsigned char *);
 
 void ge_scalarmult(ge_p2 *, const unsigned char *, const ge_p3 *);
 void ge_double_scalarmult_precomp_vartime(ge_p2 *, const unsigned char *, const ge_p3 *, const unsigned char *, const ge_dsmp);
+void ge_double_scalarmult_precomp_vartime2(ge_p2 *, const unsigned char *, const ge_dsmp, const unsigned char *, const ge_dsmp);
 void ge_mul8(ge_p1p1 *, const ge_p2 *);
 extern const fe fe_ma2;
 extern const fe fe_ma;
diff --git a/src/ringct/rctOps.cpp b/src/ringct/rctOps.cpp
index 292bb8f37..8e94b52b3 100644
--- a/src/ringct/rctOps.cpp
+++ b/src/ringct/rctOps.cpp
@@ -262,6 +262,15 @@ namespace rct {
         ge_tobytes(aAbB.bytes, &rv);
     }
 
+    //addKeys3
+    //aAbB = a*A + b*B where a, b are scalars, A, B are curve points
+    //A and B must be input after applying "precomp"
+    void addKeys3(key &aAbB, const key &a, const ge_dsmp A, const key &b, const ge_dsmp B) {
+        ge_p2 rv;
+        ge_double_scalarmult_precomp_vartime2(&rv, a.bytes, A, b.bytes, B);
+        ge_tobytes(aAbB.bytes, &rv);
+    }
+
 
     //subtract Keys (subtracts curve points)
     //AB = A - B where A, B are curve points
diff --git a/src/ringct/rctOps.h b/src/ringct/rctOps.h
index 1ff2e257b..3f8f6955c 100644
--- a/src/ringct/rctOps.h
+++ b/src/ringct/rctOps.h
@@ -134,6 +134,7 @@ namespace rct {
     //aAbB = a*A + b*B where a, b are scalars, A, B are curve points
     //B must be input after applying "precomp"
     void addKeys3(key &aAbB, const key &a, const key &A, const key &b, const ge_dsmp B);
+    void addKeys3(key &aAbB, const key &a, const ge_dsmp A, const key &b, const ge_dsmp B);
     //AB = A - B where A, B are curve points
     void subKeys(key &AB, const key &A, const  key &B);
     //checks if A, B are equal as curve points