From a073923a82e10a667a40281df1cd7b91741ceb16 Mon Sep 17 00:00:00 2001
From: SChernykh <sergey.v.chernykh@gmail.com>
Date: Tue, 5 Apr 2022 11:32:39 +0200
Subject: [PATCH] Updated dependencies

---
 external/src/cryptonote/crypto-ops.c | 50 ++++++++++++++++++++++++----
 external/src/cryptonote/crypto-ops.h |  2 +-
 2 files changed, 44 insertions(+), 8 deletions(-)

diff --git a/external/src/cryptonote/crypto-ops.c b/external/src/cryptonote/crypto-ops.c
index 7ad465b..0424c50 100644
--- a/external/src/cryptonote/crypto-ops.c
+++ b/external/src/cryptonote/crypto-ops.c
@@ -3831,15 +3831,51 @@ int sc_isnonzero(const unsigned char *s) {
     s[27] | s[28] | s[29] | s[30] | s[31]) - 1) >> 8) + 1;
 }
 
-int ge_p3_is_point_at_infinity(const ge_p3 *p) {
-  // X = 0 and Y == Z
-  int n;
-  for (n = 0; n < 10; ++n)
+int ge_p3_is_point_at_infinity_vartime(const ge_p3 *p) {
+  // https://eprint.iacr.org/2008/522
+  // X == T == 0 and Y/Z == 1
+  // note: convert all pieces to canonical bytes in case rounding is required (i.e. an element is > q)
+  // note2: even though T = XY/Z is true for valid point representations (implying it isn't necessary to
+  //        test T == 0), the input to this function might NOT be valid, so we must test T == 0
+  char result_X_bytes[32];
+  fe_tobytes((unsigned char*)&result_X_bytes, p->X);
+
+  // X != 0
+  for (int i = 0; i < 32; ++i)
   {
-    if (p->X[n] | p->T[n])
+    if (result_X_bytes[i])
       return 0;
-    if (p->Y[n] != p->Z[n])
+  }
+
+  char result_T_bytes[32];
+  fe_tobytes((unsigned char*)&result_T_bytes, p->T);
+
+  // T != 0
+  for (int i = 0; i < 32; ++i)
+  {
+    if (result_T_bytes[i])
+      return 0;
+  }
+
+  char result_Y_bytes[32];
+  char result_Z_bytes[32];
+  fe_tobytes((unsigned char*)&result_Y_bytes, p->Y);
+  fe_tobytes((unsigned char*)&result_Z_bytes, p->Z);
+
+  // Y != Z
+  for (int i = 0; i < 32; ++i)
+  {
+    if (result_Y_bytes[i] != result_Z_bytes[i])
       return 0;
   }
-  return 1;
+
+  // is Y nonzero? then Y/Z == 1
+  for (int i = 0; i < 32; ++i)
+  {
+    if (result_Y_bytes[i] != 0)
+      return 1;
+  }
+
+  // Y/Z = 0/0
+  return 0;
 }
diff --git a/external/src/cryptonote/crypto-ops.h b/external/src/cryptonote/crypto-ops.h
index 22f7697..96da16c 100644
--- a/external/src/cryptonote/crypto-ops.h
+++ b/external/src/cryptonote/crypto-ops.h
@@ -162,4 +162,4 @@ void fe_add(fe h, const fe f, const fe g);
 void fe_tobytes(unsigned char *, const fe);
 void fe_invert(fe out, const fe z);
 
-int ge_p3_is_point_at_infinity(const ge_p3 *p);
+int ge_p3_is_point_at_infinity_vartime(const ge_p3 *p);