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tls: simplify array manipulations in sp_256_ecc_mulmod_10

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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2021-04-26 14:55:46 +02:00
parent 166363f47d
commit 03ab2a90bb
1 changed files with 17 additions and 18 deletions
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35
networking/tls_sp_c32.c
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@ -788,29 +788,25 @@ static void sp_256_proj_point_add_10(sp_point* r, sp_point* p, sp_point* q,
* r Resulting point. * r Resulting point.
* g Point to multiply. * g Point to multiply.
* k Scalar to multiply by. * k Scalar to multiply by.
* map Indicates whether to convert result to affine.
*/ */
static void sp_256_ecc_mulmod_10(sp_point* r, const sp_point* g, const sp_digit* k /*, int map*/) static void sp_256_ecc_mulmod_10(sp_point* r, const sp_point* g, const sp_digit* k /*, int map*/)
{ {
enum { map = 1 }; /* we always convert result to affine coordinates */ enum { map = 1 }; /* we always convert result to affine coordinates */
sp_point td[3]; sp_point t[3];
sp_point* t[3];
sp_digit tmp[2 * 10 * 5]; sp_digit tmp[2 * 10 * 5];
sp_digit n; sp_digit n;
int i; int i;
int c, y; int c, y;
memset(td, 0, sizeof(td)); memset(t, 0, sizeof(t));
t[0] = &td[0];
t[1] = &td[1];
t[2] = &td[2];
/* t[0] = {0, 0, 1} * norm */ /* t[0] = {0, 0, 1} * norm */
t[0]->infinity = 1; t[0].infinity = 1;
/* t[1] = {g->x, g->y, g->z} * norm */ /* t[1] = {g->x, g->y, g->z} * norm */
sp_256_mod_mul_norm_10(t[1]->x, g->x); sp_256_mod_mul_norm_10(t[1].x, g->x);
sp_256_mod_mul_norm_10(t[1]->y, g->y); sp_256_mod_mul_norm_10(t[1].y, g->y);
sp_256_mod_mul_norm_10(t[1]->z, g->z); sp_256_mod_mul_norm_10(t[1].z, g->z);
i = 9; i = 9;
c = 22; c = 22;
@ -827,19 +823,21 @@ static void sp_256_ecc_mulmod_10(sp_point* r, const sp_point* g, const sp_digit*
y = (n >> 25) & 1; y = (n >> 25) & 1;
n <<= 1; n <<= 1;
sp_256_proj_point_add_10(t[y^1], t[0], t[1], tmp); //FIXME: what's "tmp" and why do we pass it down?
memcpy(t[2], t[y], sizeof(sp_point)); //is it scratch space for "sensitive" data, to be memset(0) after we are done?
sp_256_proj_point_dbl_10(t[2], t[2], tmp); sp_256_proj_point_add_10(&t[y^1], &t[0], &t[1], tmp);
memcpy(t[y], t[2], sizeof(sp_point)); memcpy(&t[2], &t[y], sizeof(sp_point));
sp_256_proj_point_dbl_10(&t[2], &t[2], tmp);
memcpy(&t[y], &t[2], sizeof(sp_point));
} }
if (map) if (map)
sp_256_map_10(r, t[0], tmp); sp_256_map_10(r, &t[0], tmp);
else else
memcpy(r, t[0], sizeof(sp_point)); memcpy(r, &t[0], sizeof(sp_point));
memset(tmp, 0, sizeof(tmp)); //paranoia memset(tmp, 0, sizeof(tmp)); //paranoia
memset(td, 0, sizeof(td)); //paranoia memset(t, 0, sizeof(t)); //paranoia
} }
/* Multiply the base point of P256 by the scalar and return the result. /* Multiply the base point of P256 by the scalar and return the result.
@ -847,6 +845,7 @@ static void sp_256_ecc_mulmod_10(sp_point* r, const sp_point* g, const sp_digit*
* *
* r Resulting point. * r Resulting point.
* k Scalar to multiply by. * k Scalar to multiply by.
* map Indicates whether to convert result to affine.
*/ */
static void sp_256_ecc_mulmod_base_10(sp_point* r, sp_digit* k /*, int map*/) static void sp_256_ecc_mulmod_base_10(sp_point* r, sp_digit* k /*, int map*/)
{ {