diff options
| author | Brian Smith <brian@briansmith.org> | 2016-03-26 03:22:40 +0300 |
|---|---|---|
| committer | David Benjamin <davidben@google.com> | 2016-04-21 01:53:46 +0300 |
| commit | a7aa2bb8f86f9891bba9d05544e2b9796b2da864 (patch) | |
| tree | cab8f59cfaf3ddc3f4274a51f5fa266ca197f7a4 /crypto/ec | |
| parent | d860b7b1cdefa22b2d42074aa5c8ce2a8ec1da5c (diff) | |
Avoid a multiplication in |ecp_nistz256_get_affine| when |x| is NULL.
This is purely hypothetical, as in real life nobody cares about the
|y| component without also caring about the |x| component, but it
clarifies the code and makes a future change clearer.
Change-Id: Icaa4de83c87b82a8e68cd2942779a06e5db300c3
Reviewed-on: https://boringssl-review.googlesource.com/7588
Reviewed-by: David Benjamin <davidben@google.com>
Diffstat (limited to 'crypto/ec')
| -rw-r--r-- | crypto/ec/p256-x86_64.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/crypto/ec/p256-x86_64.c b/crypto/ec/p256-x86_64.c index 17ab91b3..b11e37fd 100644 --- a/crypto/ec/p256-x86_64.c +++ b/crypto/ec/p256-x86_64.c @@ -502,8 +502,6 @@ static int ecp_nistz256_get_affine(const EC_GROUP *group, const EC_POINT *point, BIGNUM *x, BIGNUM *y, BN_CTX *ctx) { BN_ULONG z_inv2[P256_LIMBS]; BN_ULONG z_inv3[P256_LIMBS]; - BN_ULONG x_aff[P256_LIMBS]; - BN_ULONG y_aff[P256_LIMBS]; BN_ULONG point_x[P256_LIMBS], point_y[P256_LIMBS], point_z[P256_LIMBS]; if (EC_POINT_is_at_infinity(group, point)) { @@ -520,9 +518,11 @@ static int ecp_nistz256_get_affine(const EC_GROUP *group, const EC_POINT *point, ecp_nistz256_mod_inverse(z_inv3, point_z); ecp_nistz256_sqr_mont(z_inv2, z_inv3); - ecp_nistz256_mul_mont(x_aff, z_inv2, point_x); if (x != NULL) { + BN_ULONG x_aff[P256_LIMBS]; + + ecp_nistz256_mul_mont(x_aff, z_inv2, point_x); if (bn_wexpand(x, P256_LIMBS) == NULL) { OPENSSL_PUT_ERROR(EC, ERR_R_MALLOC_FAILURE); return 0; @@ -534,6 +534,8 @@ static int ecp_nistz256_get_affine(const EC_GROUP *group, const EC_POINT *point, } if (y != NULL) { + BN_ULONG y_aff[P256_LIMBS]; + 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) { |