From e37ba822e627550a453a1678d180f7e056b3d98f Mon Sep 17 00:00:00 2001
From: Pavol Rusnak <stick@gk2.sk>
Date: Tue, 17 Mar 2015 14:15:38 +0100
Subject: [PATCH] bn_substract -> bn_subtractmod, bn_substract_noprime ->
 bn_subtract remove dead code

---
 bignum.c | 27 ++-------------------------
 bignum.h |  8 ++------
 ecdsa.c  | 16 ++++++++--------
 3 files changed, 12 insertions(+), 39 deletions(-)

diff --git a/bignum.c b/bignum.c
index 60846195aa..7c1484962c 100644
--- a/bignum.c
+++ b/bignum.c
@@ -154,29 +154,6 @@ void bn_mod(bignum256 *x, const bignum256 *prime)
 	}
 }
 
-// a = a + b
-void bn_addi(bignum256 *a, uint32_t b)
-{
-	uint64_t t = a->val[0];
-	t += b;
-	a->val[0] = t & 0x3FFFFFFFu;
-	t >>= 30;
-	a->val[1] += t;
-}
-
-// a = a * b
-void bn_muli(bignum256 *a, uint32_t b)
-{
-	uint64_t t = 0;
-	int i;
-	for (i = 0; i < 8; i++) {
-		t = (uint64_t)(a->val[i]) * b + t;
-		a->val[i] = t & 0x3FFFFFFFu;
-		t >>= 30;
-	}
-	a->val[8] += t;
-}
-
 // Compute x := k * x  (mod prime)
 // both inputs must be smaller than 2 * prime.
 // result is reduced to 0 <= x < 2 * prime
@@ -657,7 +634,7 @@ void bn_addmodi(bignum256 *a, uint32_t b, const bignum256 *prime) {
 
 // res = a - b
 // b < 2*prime; result not normalized
-void bn_substract(const bignum256 *a, const bignum256 *b, bignum256 *res)
+void bn_subtractmod(const bignum256 *a, const bignum256 *b, bignum256 *res)
 {
 	int i;
 	uint32_t temp = 0;
@@ -669,7 +646,7 @@ void bn_substract(const bignum256 *a, const bignum256 *b, bignum256 *res)
 }
 
 // res = a - b ; a > b
-void bn_substract_noprime(const bignum256 *a, const bignum256 *b, bignum256 *res)
+void bn_subtract(const bignum256 *a, const bignum256 *b, bignum256 *res)
 {
 	int i;
 	uint32_t tmp = 1;
diff --git a/bignum.h b/bignum.h
index 168354643c..de71fba0eb 100644
--- a/bignum.h
+++ b/bignum.h
@@ -59,10 +59,6 @@ void bn_rshift(bignum256 *a);
 
 void bn_mod(bignum256 *x, const bignum256 *prime);
 
-void bn_addi(bignum256 *a, uint32_t b);
-
-void bn_muli(bignum256 *a, uint32_t b);
-
 void bn_multiply(const bignum256 *k, bignum256 *x, const bignum256 *prime);
 
 void bn_fast_mod(bignum256 *x, const bignum256 *prime);
@@ -77,9 +73,9 @@ void bn_addmod(bignum256 *a, const bignum256 *b, const bignum256 *prime);
 
 void bn_addmodi(bignum256 *a, uint32_t b, const bignum256 *prime);
 
-void bn_substract(const bignum256 *a, const bignum256 *b, bignum256 *res);
+void bn_subtractmod(const bignum256 *a, const bignum256 *b, bignum256 *res);
 
-void bn_substract_noprime(const bignum256 *a, const bignum256 *b, bignum256 *res);
+void bn_subtract(const bignum256 *a, const bignum256 *b, bignum256 *res);
 
 void bn_divmod58(bignum256 *a, uint32_t *r);
 
diff --git a/ecdsa.c b/ecdsa.c
index 831098cb22..0c5b5a625b 100644
--- a/ecdsa.c
+++ b/ecdsa.c
@@ -63,9 +63,9 @@ void point_add(const curve_point *cp1, curve_point *cp2)
 		return;
 	}
 
-	bn_substract(&(cp2->x), &(cp1->x), &inv);
+	bn_subtractmod(&(cp2->x), &(cp1->x), &inv);
 	bn_inverse(&inv, &prime256k1);
-	bn_substract(&(cp2->y), &(cp1->y), &lambda);
+	bn_subtractmod(&(cp2->y), &(cp1->y), &lambda);
 	bn_multiply(&inv, &lambda, &prime256k1);
 	memcpy(&xr, &lambda, sizeof(bignum256));
 	bn_multiply(&xr, &xr, &prime256k1);
@@ -76,11 +76,11 @@ void point_add(const curve_point *cp1, curve_point *cp2)
 		temp >>= 30;
 	}
 	bn_fast_mod(&xr, &prime256k1);
-	bn_substract(&(cp1->x), &xr, &yr);
+	bn_subtractmod(&(cp1->x), &xr, &yr);
 	// no need to fast_mod here
 	// bn_fast_mod(&yr);
 	bn_multiply(&lambda, &yr, &prime256k1);
-	bn_substract(&yr, &(cp1->y), &yr);
+	bn_subtractmod(&yr, &(cp1->y), &yr);
 	bn_fast_mod(&yr, &prime256k1);
 	memcpy(&(cp2->x), &xr, sizeof(bignum256));
 	memcpy(&(cp2->y), &yr, sizeof(bignum256));
@@ -118,11 +118,11 @@ void point_double(curve_point *cp)
 		temp >>= 30;
 	}
 	bn_fast_mod(&xr, &prime256k1);
-	bn_substract(&(cp->x), &xr, &yr);
+	bn_subtractmod(&(cp->x), &xr, &yr);
 	// no need to fast_mod here
 	// bn_fast_mod(&yr);
 	bn_multiply(&lambda, &yr, &prime256k1);
-	bn_substract(&yr, &(cp->y), &yr);
+	bn_subtractmod(&yr, &(cp->y), &yr);
 	bn_fast_mod(&yr, &prime256k1);
 	memcpy(&(cp->x), &xr, sizeof(bignum256));
 	memcpy(&(cp->y), &yr, sizeof(bignum256));
@@ -363,7 +363,7 @@ int ecdsa_sign_digest(const uint8_t *priv_key, const uint8_t *digest, uint8_t *s
 
 	// if S > order/2 => S = -S
 	if (bn_is_less(&order256k1_half, &k)) {
-		bn_substract_noprime(&order256k1, &k, &k);
+		bn_subtract(&order256k1, &k, &k);
 		if (pby) {
 			*pby = !*pby;
 		}
@@ -451,7 +451,7 @@ void uncompress_coords(uint8_t odd, const bignum256 *x, bignum256 *y)
 	bn_addmodi(y, 7, &prime256k1);         // y is x^3 + 7
 	bn_sqrt(y, &prime256k1);               // y = sqrt(y)
 	if ((odd & 0x01) != (y->val[0] & 1)) {
-		bn_substract_noprime(&prime256k1, y, y);   // y = -y
+		bn_subtract(&prime256k1, y, y);   // y = -y
 	}
 }