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authorDenys Vlasenko2021-04-26 17:41:43 +0200
committerDenys Vlasenko2021-04-26 17:41:43 +0200
commit6381f3d4f6d9ac111c2be7cfba041e8b7a28f9f9 (patch)
tree811e52506550874fe82f2fa9e85c87ec9497c76b
parent772e18775e0e1db2392dcbea970d5729018437e8 (diff)
downloadbusybox-6381f3d4f6d9ac111c2be7cfba041e8b7a28f9f9.zip
busybox-6381f3d4f6d9ac111c2be7cfba041e8b7a28f9f9.tar.gz
tls: stop passing temporary buffer address in P256 code
function old new delta sp_256_proj_point_dbl_10 435 453 +18 sp_256_ecc_mulmod_10 1300 1237 -63 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 1/1 up/down: 18/-63) Total: -45 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--networking/tls_sp_c32.c61
1 files changed, 26 insertions, 35 deletions
diff --git a/networking/tls_sp_c32.c b/networking/tls_sp_c32.c
index 70e20aa..c71f716 100644
--- a/networking/tls_sp_c32.c
+++ b/networking/tls_sp_c32.c
@@ -170,8 +170,8 @@ static sp_digit sp_256_cmp_10(const sp_digit* a, const sp_digit* b)
int i;
for (i = 9; i >= 0; i--) {
r = a[i] - b[i];
- if (r != 0)
- break;
+ if (r != 0)
+ break;
}
return r;
}
@@ -553,16 +553,15 @@ static void sp_256_mont_sqr_10(sp_digit* r, const sp_digit* a, const sp_digit* m
*
* r Inverse result.
* a Number to invert.
- * td Temporary data.
*/
/* Mod-2 for the P256 curve. */
static const uint32_t p256_mod_2[8] = {
- 0xfffffffd,0xffffffff,0xffffffff,0x00000000,
- 0x00000000,0x00000000,0x00000001,0xffffffff,
+ 0xfffffffd,0xffffffff,0xffffffff,0x00000000,
+ 0x00000000,0x00000000,0x00000001,0xffffffff,
};
-static void sp_256_mont_inv_10(sp_digit* r, sp_digit* a, sp_digit* td)
+static void sp_256_mont_inv_10(sp_digit* r, sp_digit* a)
{
- sp_digit* t = td;
+ sp_digit t[2*10]; //can be just [10]?
int i;
memcpy(t, a, sizeof(sp_digit) * 10);
@@ -578,15 +577,14 @@ static void sp_256_mont_inv_10(sp_digit* r, sp_digit* a, sp_digit* td)
*
* r Resulting affine co-ordinate point.
* p Montgomery form projective co-ordinate point.
- * t Temporary ordinate data.
*/
-static void sp_256_map_10(sp_point* r, sp_point* p, sp_digit* t)
+static void sp_256_map_10(sp_point* r, sp_point* p)
{
- sp_digit* t1 = t;
- sp_digit* t2 = t + 2*10;
+ sp_digit t1[2*10];
+ sp_digit t2[2*10];
int32_t n;
- sp_256_mont_inv_10(t1, p->z, t + 2*10);
+ sp_256_mont_inv_10(t1, p->z);
sp_256_mont_sqr_10(t2, t1, p256_mod, p256_mp_mod);
sp_256_mont_mul_10(t1, t2, t1, p256_mod, p256_mp_mod);
@@ -617,21 +615,20 @@ static void sp_256_map_10(sp_point* r, sp_point* p, sp_digit* t)
*
* r Result of doubling point.
* p Point to double.
- * t Temporary ordinate data.
*/
-static void sp_256_proj_point_dbl_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_point tp;
- sp_digit* t1 = t;
- sp_digit* t2 = t + 2*10;
+ sp_digit t1[2*10];
+ sp_digit t2[2*10];
/* 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;
+ /* If infinity, don't double (work on dummy value) */
+ r = &tp;
}
/* T1 = Z * Z */
sp_256_mont_sqr_10(t1, r->z, p256_mod, p256_mp_mod);
@@ -676,16 +673,14 @@ static void sp_256_proj_point_dbl_10(sp_point* r, sp_point* p, sp_digit* t)
* r Result of addition.
* p Frist point to add.
* q Second point to add.
- * t Temporary ordinate data.
*/
-static void sp_256_proj_point_add_10(sp_point* r, sp_point* p, sp_point* q,
- sp_digit* t)
+static void sp_256_proj_point_add_10(sp_point* r, sp_point* p, sp_point* q)
{
- sp_digit* t1 = t;
- sp_digit* t2 = t + 2*10;
- sp_digit* t3 = t + 4*10;
- sp_digit* t4 = t + 6*10;
- sp_digit* t5 = t + 8*10;
+ sp_digit t1[2*10];
+ sp_digit t2[2*10];
+ sp_digit t3[2*10];
+ sp_digit t4[2*10];
+ sp_digit t5[2*10];
/* Ensure only the first point is the same as the result. */
if (q == r) {
@@ -701,7 +696,7 @@ static void sp_256_proj_point_add_10(sp_point* r, sp_point* p, sp_point* q,
&& sp_256_cmp_equal_10(p->z, q->z)
&& (sp_256_cmp_equal_10(p->y, q->y) || sp_256_cmp_equal_10(p->y, t1))
) {
- sp_256_proj_point_dbl_10(r, p, t);
+ sp_256_proj_point_dbl_10(r, p);
}
else {
sp_point tp;
@@ -762,7 +757,6 @@ static void sp_256_ecc_mulmod_10(sp_point* r, const sp_point* g, const sp_digit*
{
enum { map = 1 }; /* we always convert result to affine coordinates */
sp_point t[3];
- sp_digit tmp[2 * 10 * 5];
sp_digit n;
int i;
int c, y;
@@ -791,20 +785,17 @@ static void sp_256_ecc_mulmod_10(sp_point* r, const sp_point* g, const sp_digit*
y = (n >> 25) & 1;
n <<= 1;
-//FIXME: what's "tmp" and why do we pass it down?
-//is it scratch space for "sensitive" data, to be memset(0) after we are done?
- sp_256_proj_point_add_10(&t[y^1], &t[0], &t[1], tmp);
+ sp_256_proj_point_add_10(&t[y^1], &t[0], &t[1]);
memcpy(&t[2], &t[y], sizeof(sp_point));
- sp_256_proj_point_dbl_10(&t[2], &t[2], tmp);
+ sp_256_proj_point_dbl_10(&t[2], &t[2]);
memcpy(&t[y], &t[2], sizeof(sp_point));
}
if (map)
- sp_256_map_10(r, &t[0], tmp);
+ sp_256_map_10(r, &t[0]);
else
memcpy(r, &t[0], sizeof(sp_point));
- memset(tmp, 0, sizeof(tmp)); //paranoia
memset(t, 0, sizeof(t)); //paranoia
}
@@ -817,7 +808,7 @@ static void sp_256_ecc_mulmod_10(sp_point* r, const sp_point* g, const sp_digit*
*/
static void sp_256_ecc_mulmod_base_10(sp_point* r, sp_digit* k /*, int map*/)
{
- sp_256_ecc_mulmod_10(r, &p256_base, k /*, map*/);
+ sp_256_ecc_mulmod_10(r, &p256_base, k /*, map*/);
}
/* Multiply the point by the scalar and serialize the X ordinate.