From 97c57f42ba8aca51479d23874b7608b9500a5bc9 Mon Sep 17 00:00:00 2001
From: Tim Ruffing <crypto@timruffing.de>
Date: Sat, 8 Jun 2019 11:29:49 +0200
Subject: [PATCH] Implement various _clear() functions with
 secp256k1_memclear()

---
 src/field.h            |  1 -
 src/field_10x26_impl.h |  7 -------
 src/field_5x52_impl.h  |  7 -------
 src/field_impl.h       | 13 ++++---------
 src/group_impl.h       | 13 ++-----------
 src/scalar_4x64_impl.h |  7 -------
 src/scalar_8x32_impl.h | 11 -----------
 src/scalar_impl.h      |  4 ++++
 src/scalar_low_impl.h  |  2 --
 9 files changed, 10 insertions(+), 55 deletions(-)

diff --git a/src/field.h b/src/field.h
index 95990309..1f6ba746 100644
--- a/src/field.h
+++ b/src/field.h
@@ -81,7 +81,6 @@ static const secp256k1_fe secp256k1_const_beta = SECP256K1_FE_CONST(
 #  define secp256k1_fe_normalizes_to_zero secp256k1_fe_impl_normalizes_to_zero
 #  define secp256k1_fe_normalizes_to_zero_var secp256k1_fe_impl_normalizes_to_zero_var
 #  define secp256k1_fe_set_int secp256k1_fe_impl_set_int
-#  define secp256k1_fe_clear secp256k1_fe_impl_clear
 #  define secp256k1_fe_is_zero secp256k1_fe_impl_is_zero
 #  define secp256k1_fe_is_odd secp256k1_fe_impl_is_odd
 #  define secp256k1_fe_cmp_var secp256k1_fe_impl_cmp_var
diff --git a/src/field_10x26_impl.h b/src/field_10x26_impl.h
index 666068c7..ea14c273 100644
--- a/src/field_10x26_impl.h
+++ b/src/field_10x26_impl.h
@@ -270,13 +270,6 @@ SECP256K1_INLINE static int secp256k1_fe_impl_is_odd(const secp256k1_fe *a) {
     return a->n[0] & 1;
 }
 
-SECP256K1_INLINE static void secp256k1_fe_impl_clear(secp256k1_fe *a) {
-    int i;
-    for (i=0; i<10; i++) {
-        a->n[i] = 0;
-    }
-}
-
 static int secp256k1_fe_impl_cmp_var(const secp256k1_fe *a, const secp256k1_fe *b) {
     int i;
     for (i = 9; i >= 0; i--) {
diff --git a/src/field_5x52_impl.h b/src/field_5x52_impl.h
index 76031f75..46dca6b9 100644
--- a/src/field_5x52_impl.h
+++ b/src/field_5x52_impl.h
@@ -212,13 +212,6 @@ SECP256K1_INLINE static int secp256k1_fe_impl_is_odd(const secp256k1_fe *a) {
     return a->n[0] & 1;
 }
 
-SECP256K1_INLINE static void secp256k1_fe_impl_clear(secp256k1_fe *a) {
-    int i;
-    for (i=0; i<5; i++) {
-        a->n[i] = 0;
-    }
-}
-
 static int secp256k1_fe_impl_cmp_var(const secp256k1_fe *a, const secp256k1_fe *b) {
     int i;
     for (i = 4; i >= 0; i--) {
diff --git a/src/field_impl.h b/src/field_impl.h
index 8cf6f22c..896507a3 100644
--- a/src/field_impl.h
+++ b/src/field_impl.h
@@ -18,6 +18,10 @@
 #error "Please select wide multiplication implementation"
 #endif
 
+SECP256K1_INLINE static void secp256k1_fe_clear(secp256k1_fe *a) {
+    secp256k1_memclear(a, sizeof(secp256k1_fe));
+}
+
 SECP256K1_INLINE static int secp256k1_fe_equal(const secp256k1_fe *a, const secp256k1_fe *b) {
     secp256k1_fe na;
     SECP256K1_FE_VERIFY(a);
@@ -232,15 +236,6 @@ SECP256K1_INLINE static void secp256k1_fe_add_int(secp256k1_fe *r, int a) {
     SECP256K1_FE_VERIFY(r);
 }
 
-static void secp256k1_fe_impl_clear(secp256k1_fe *a);
-SECP256K1_INLINE static void secp256k1_fe_clear(secp256k1_fe *a) {
-    a->magnitude = 0;
-    a->normalized = 0;
-    secp256k1_fe_impl_clear(a);
-
-    SECP256K1_FE_VERIFY(a);
-}
-
 static int secp256k1_fe_impl_is_zero(const secp256k1_fe *a);
 SECP256K1_INLINE static int secp256k1_fe_is_zero(const secp256k1_fe *a) {
     SECP256K1_FE_VERIFY(a);
diff --git a/src/group_impl.h b/src/group_impl.h
index 10aff433..c668fb24 100644
--- a/src/group_impl.h
+++ b/src/group_impl.h
@@ -299,20 +299,11 @@ static void secp256k1_ge_set_infinity(secp256k1_ge *r) {
 }
 
 static void secp256k1_gej_clear(secp256k1_gej *r) {
-    r->infinity = 0;
-    secp256k1_fe_clear(&r->x);
-    secp256k1_fe_clear(&r->y);
-    secp256k1_fe_clear(&r->z);
-
-    SECP256K1_GEJ_VERIFY(r);
+    secp256k1_memclear(r, sizeof(secp256k1_gej));
 }
 
 static void secp256k1_ge_clear(secp256k1_ge *r) {
-    r->infinity = 0;
-    secp256k1_fe_clear(&r->x);
-    secp256k1_fe_clear(&r->y);
-
-    SECP256K1_GE_VERIFY(r);
+    secp256k1_memclear(r, sizeof(secp256k1_ge));
 }
 
 static int secp256k1_ge_set_xo_var(secp256k1_ge *r, const secp256k1_fe *x, int odd) {
diff --git a/src/scalar_4x64_impl.h b/src/scalar_4x64_impl.h
index 4aaec85b..807b9b70 100644
--- a/src/scalar_4x64_impl.h
+++ b/src/scalar_4x64_impl.h
@@ -29,13 +29,6 @@
 #define SECP256K1_N_H_2 ((uint64_t)0xFFFFFFFFFFFFFFFFULL)
 #define SECP256K1_N_H_3 ((uint64_t)0x7FFFFFFFFFFFFFFFULL)
 
-SECP256K1_INLINE static void secp256k1_scalar_clear(secp256k1_scalar *r) {
-    r->d[0] = 0;
-    r->d[1] = 0;
-    r->d[2] = 0;
-    r->d[3] = 0;
-}
-
 SECP256K1_INLINE static void secp256k1_scalar_set_int(secp256k1_scalar *r, unsigned int v) {
     r->d[0] = v;
     r->d[1] = 0;
diff --git a/src/scalar_8x32_impl.h b/src/scalar_8x32_impl.h
index c7d87b17..26104960 100644
--- a/src/scalar_8x32_impl.h
+++ b/src/scalar_8x32_impl.h
@@ -38,17 +38,6 @@
 #define SECP256K1_N_H_6 ((uint32_t)0xFFFFFFFFUL)
 #define SECP256K1_N_H_7 ((uint32_t)0x7FFFFFFFUL)
 
-SECP256K1_INLINE static void secp256k1_scalar_clear(secp256k1_scalar *r) {
-    r->d[0] = 0;
-    r->d[1] = 0;
-    r->d[2] = 0;
-    r->d[3] = 0;
-    r->d[4] = 0;
-    r->d[5] = 0;
-    r->d[6] = 0;
-    r->d[7] = 0;
-}
-
 SECP256K1_INLINE static void secp256k1_scalar_set_int(secp256k1_scalar *r, unsigned int v) {
     r->d[0] = v;
     r->d[1] = 0;
diff --git a/src/scalar_impl.h b/src/scalar_impl.h
index 972d8041..dbb5b0a0 100644
--- a/src/scalar_impl.h
+++ b/src/scalar_impl.h
@@ -27,6 +27,10 @@
 static const secp256k1_scalar secp256k1_scalar_one = SECP256K1_SCALAR_CONST(0, 0, 0, 0, 0, 0, 0, 1);
 static const secp256k1_scalar secp256k1_scalar_zero = SECP256K1_SCALAR_CONST(0, 0, 0, 0, 0, 0, 0, 0);
 
+SECP256K1_INLINE static void secp256k1_scalar_clear(secp256k1_scalar *r) {
+    secp256k1_memclear(r, sizeof(secp256k1_scalar));
+}
+
 static int secp256k1_scalar_set_b32_seckey(secp256k1_scalar *r, const unsigned char *bin) {
     int overflow;
     secp256k1_scalar_set_b32(r, bin, &overflow);
diff --git a/src/scalar_low_impl.h b/src/scalar_low_impl.h
index 45d2f3e4..84e1a380 100644
--- a/src/scalar_low_impl.h
+++ b/src/scalar_low_impl.h
@@ -19,8 +19,6 @@ SECP256K1_INLINE static int secp256k1_scalar_is_even(const secp256k1_scalar *a)
     return !(*a & 1);
 }
 
-SECP256K1_INLINE static void secp256k1_scalar_clear(secp256k1_scalar *r) { *r = 0; }
-
 SECP256K1_INLINE static void secp256k1_scalar_set_int(secp256k1_scalar *r, unsigned int v) {
     *r = v % EXHAUSTIVE_TEST_ORDER;