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Save one call to |ecp_nistz256_from_mont| in |ecp_nistz256_get_affine|.

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Change-Id: I38faa5c4e9101c100614ebadf421bde0a05af360
Reviewed-on: https://boringssl-review.googlesource.com/7589
Reviewed-by: David Benjamin <davidben@google.com>
This commit is contained in:
Brian Smith 2016-03-25 14:29:52 -10:00 committed by David Benjamin
parent a7aa2bb8f8
commit 3f3358ac15
1 changed files with 8 additions and 8 deletions
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16
crypto/ec/p256-x86_64.c
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@ -519,32 +519,32 @@ static int ecp_nistz256_get_affine(const EC_GROUP *group, const EC_POINT *point,
ecp_nistz256_mod_inverse(z_inv3, point_z); ecp_nistz256_mod_inverse(z_inv3, point_z);
ecp_nistz256_sqr_mont(z_inv2, z_inv3); ecp_nistz256_sqr_mont(z_inv2, z_inv3);
if (x != NULL) { /* Instead of using |ecp_nistz256_from_mont| to convert the |x| coordinate
BN_ULONG x_aff[P256_LIMBS]; * and then calling |ecp_nistz256_from_mont| again to convert the |y|
* coordinate below, convert the common factor |z_inv2| once now, saving one
* reduction. */
ecp_nistz256_from_mont(z_inv2, z_inv2);
ecp_nistz256_mul_mont(x_aff, z_inv2, point_x); if (x != NULL) {
if (bn_wexpand(x, P256_LIMBS) == NULL) { if (bn_wexpand(x, P256_LIMBS) == NULL) {
OPENSSL_PUT_ERROR(EC, ERR_R_MALLOC_FAILURE); OPENSSL_PUT_ERROR(EC, ERR_R_MALLOC_FAILURE);
return 0; return 0;
} }
x->top = P256_LIMBS; x->top = P256_LIMBS;
x->neg = 0; x->neg = 0;
ecp_nistz256_from_mont(x->d, x_aff); ecp_nistz256_mul_mont(x->d, z_inv2, point_x);
bn_correct_top(x); bn_correct_top(x);
} }
if (y != NULL) { if (y != NULL) {
BN_ULONG y_aff[P256_LIMBS];
ecp_nistz256_mul_mont(z_inv3, z_inv3, z_inv2); ecp_nistz256_mul_mont(z_inv3, z_inv3, z_inv2);
ecp_nistz256_mul_mont(y_aff, z_inv3, point_y);
if (bn_wexpand(y, P256_LIMBS) == NULL) { if (bn_wexpand(y, P256_LIMBS) == NULL) {
OPENSSL_PUT_ERROR(EC, ERR_R_MALLOC_FAILURE); OPENSSL_PUT_ERROR(EC, ERR_R_MALLOC_FAILURE);
return 0; return 0;
} }
y->top = P256_LIMBS; y->top = P256_LIMBS;
y->neg = 0; y->neg = 0;
ecp_nistz256_from_mont(y->d, y_aff); ecp_nistz256_mul_mont(y->d, z_inv3, point_y);
bn_correct_top(y); bn_correct_top(y);
} }