4d3a5c135 — BusyBox

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tls: simplify sp_256_proj_point_dbl_10

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Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

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networking/tls_sp_c32.c +22 -36

networking/tls_sp_c32.c+22 -36

@@ -626,68 +626,54 @@ static void sp_256_map_10(sp_point* r, sp_point* p, sp_digit* t)
	*/
	static void sp_256_proj_point_dbl_10(sp_point* r, sp_point* p, sp_digit* t)
	{
-	sp_point *rp[2];
	sp_point tp;
	sp_digit* t1 = t;
	sp_digit* t2 = t + 2*10;
-	sp_digit* x;
-	sp_digit* y;
-	sp_digit* z;
-	int i;

-	/* When infinity don't double point passed in - constant time. */
-	rp[0] = r;
-	rp[1] = &tp;
-	x = rp[p->infinity]->x;
-	y = rp[p->infinity]->y;
-	z = rp[p->infinity]->z;
-	/* Put point to double into result - good for infinity. */
-	if (r != p) {
-	for (i = 0; i < 10; i++)
-	r->x[i] = p->x[i];
-	for (i = 0; i < 10; i++)
-	r->y[i] = p->y[i];
-	for (i = 0; i < 10; i++)
-	r->z[i] = p->z[i];
-	r->infinity = p->infinity;
-	}
+	/* Put point to double into result */
+	if (r != p)
+	r = p; /* struct copy */

+	if (r->infinity) {
+	/* If infinity, don't double (work on dummy value) */
+	r = &tp;
+	}
	/* T1 = Z * Z */
-	sp_256_mont_sqr_10(t1, z, p256_mod, p256_mp_mod);
+	sp_256_mont_sqr_10(t1, r->z, p256_mod, p256_mp_mod);
	/* Z = Y * Z */
-	sp_256_mont_mul_10(z, y, z, p256_mod, p256_mp_mod);
+	sp_256_mont_mul_10(r->z, r->y, r->z, p256_mod, p256_mp_mod);
	/* Z = 2Z */
-	sp_256_mont_dbl_10(z, z, p256_mod);
+	sp_256_mont_dbl_10(r->z, r->z, p256_mod);
	/* T2 = X - T1 */
-	sp_256_mont_sub_10(t2, x, t1, p256_mod);
+	sp_256_mont_sub_10(t2, r->x, t1, p256_mod);
	/* T1 = X + T1 */
-	sp_256_mont_add_10(t1, x, t1, p256_mod);
+	sp_256_mont_add_10(t1, r->x, t1, p256_mod);
	/* T2 = T1 * T2 */
	sp_256_mont_mul_10(t2, t1, t2, p256_mod, p256_mp_mod);
	/* T1 = 3T2 */
	sp_256_mont_tpl_10(t1, t2, p256_mod);
	/* Y = 2Y */
-	sp_256_mont_dbl_10(y, y, p256_mod);
+	sp_256_mont_dbl_10(r->y, r->y, p256_mod);
	/* Y = Y * Y */
-	sp_256_mont_sqr_10(y, y, p256_mod, p256_mp_mod);
+	sp_256_mont_sqr_10(r->y, r->y, p256_mod, p256_mp_mod);
	/* T2 = Y * Y */
-	sp_256_mont_sqr_10(t2, y, p256_mod, p256_mp_mod);
+	sp_256_mont_sqr_10(t2, r->y, p256_mod, p256_mp_mod);
	/* T2 = T2/2 */
	sp_256_div2_10(t2, t2, p256_mod);
	/* Y = Y * X */
-	sp_256_mont_mul_10(y, y, x, p256_mod, p256_mp_mod);
+	sp_256_mont_mul_10(r->y, r->y, r->x, p256_mod, p256_mp_mod);
	/* X = T1 * T1 */
-	sp_256_mont_mul_10(x, t1, t1, p256_mod, p256_mp_mod);
+	sp_256_mont_mul_10(r->x, t1, t1, p256_mod, p256_mp_mod);
	/* X = X - Y */
-	sp_256_mont_sub_10(x, x, y, p256_mod);
+	sp_256_mont_sub_10(r->x, r->x, r->y, p256_mod);
	/* X = X - Y */
-	sp_256_mont_sub_10(x, x, y, p256_mod);
+	sp_256_mont_sub_10(r->x, r->x, r->y, p256_mod);
	/* Y = Y - X */
-	sp_256_mont_sub_10(y, y, x, p256_mod);
+	sp_256_mont_sub_10(r->y, r->y, r->x, p256_mod);
	/* Y = Y * T1 */
-	sp_256_mont_mul_10(y, y, t1, p256_mod, p256_mp_mod);
+	sp_256_mont_mul_10(r->y, r->y, t1, p256_mod, p256_mp_mod);
	/* Y = Y - T2 */
-	sp_256_mont_sub_10(y, y, t2, p256_mod);
+	sp_256_mont_sub_10(r->y, r->y, t2, p256_mod);
	}

	/* Add two Montgomery form projective points.