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EC_set_half and the 'h' component of struct bn_ec_struct are unnecess…
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…ary.

The computations for which h was used can be done more efficiently
by using BN_rshift1.
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@45264
45264 committed Mar 3, 2001
1 parent 794103d commit 786e0c2
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Showing 3 changed files with 20 additions and 41 deletions.
27 changes: 3 additions & 24 deletions crypto/ec/ec.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -27,15 +27,13 @@ EC *EC_new()
ret->A = BN_new();
ret->B = BN_new();
ret->p = BN_new();
ret->h = BN_new();
ret->is_in_mont = 0;

if (ret->A == NULL || ret->B == NULL || ret->p == NULL || ret->h == NULL)
if (ret->A == NULL || ret->B == NULL || ret->p == NULL)
{
if (ret->A != NULL) BN_free(ret->A);
if (ret->B != NULL) BN_free(ret->B);
if (ret->p != NULL) BN_free(ret->p);
if (ret->h != NULL) BN_free(ret->h);
free(ret);
return(NULL);
}
Expand All @@ -50,7 +48,6 @@ void EC_clear_free(EC *E)
if (E->A != NULL) BN_clear_free(E->A);
if (E->B != NULL) BN_clear_free(E->B);
if (E->p != NULL) BN_clear_free(E->p);
if (E->h != NULL) BN_clear_free(E->h);
E->is_in_mont = 0;
free(E);
}
Expand All @@ -60,7 +57,7 @@ void EC_clear_free(EC *E)
int EC_to_montgomery(EC *E, BN_MONTGOMERY *mont, BN_CTX *ctx)
{
assert(E != NULL);
assert(E->A != NULL && E->B != NULL && E->p != NULL && E->h != NULL);
assert(E->A != NULL && E->B != NULL && E->p != NULL);

assert(mont != NULL);
assert(mont->p != NULL);
Expand All @@ -75,9 +72,6 @@ int EC_to_montgomery(EC *E, BN_MONTGOMERY *mont, BN_CTX *ctx)
if (!BN_lshift(E->B, E->B, mont->R_num_bits)) return 0;
if (!BN_mod(E->B, E->B, mont->p, ctx)) return 0;

if (!BN_lshift(E->h, E->h, mont->R_num_bits)) return 0;
if (!BN_mod(E->h, E->h, mont->p, ctx)) return 0;

E->is_in_mont = 1;
return 1;

Expand All @@ -87,7 +81,7 @@ int EC_to_montgomery(EC *E, BN_MONTGOMERY *mont, BN_CTX *ctx)
int EC_from_montgomery(EC *E, BN_MONTGOMERY *mont, BN_CTX *ctx)
{
assert(E != NULL);
assert(E->A != NULL && E->B != NULL && E->p != NULL && E->h != NULL);
assert(E->A != NULL && E->B != NULL && E->p != NULL);

assert(mont != NULL);
assert(mont->p != NULL);
Expand All @@ -98,23 +92,8 @@ int EC_from_montgomery(EC *E, BN_MONTGOMERY *mont, BN_CTX *ctx)

if (!BN_mont_red(E->A, mont)) return 0;
if (!BN_mont_red(E->B, mont)) return 0;
if (!BN_mont_red(E->h, mont)) return 0;

E->is_in_mont = 0;
return 1;
}
#endif /* MONTGOMERY */

int EC_set_half(EC *E)
/* h <- 1/2 mod p = (p + 1)/2 */
{
assert(E != NULL);
assert(E->p != NULL);
assert(E->h != NULL);
assert(!E->is_in_mont);

if (BN_copy(E->h, E->p) == NULL) return 0;
if (!BN_add_word(E->h, 1)) return 0;
if (!BN_rshift1(E->h, E->h)) return 0;
return 1;
}
3 changes: 1 addition & 2 deletions crypto/ec/ec.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,7 @@

typedef struct bn_ec_struct /* E: y^2 = x^3 + Ax + B (mod p) */
{
BIGNUM *A, *B, *p, *h; /* h = 1/2 mod p = (p + 1)/2 */
BIGNUM *A, *B, *p;
int is_in_mont;
} EC;

Expand All @@ -44,7 +44,6 @@ typedef struct bn_ecp_precompute_struct /* Pi[i] = [2i + 1]P i = 0..2^{r-1} - 1

EC *EC_new();
void EC_clear_free(EC *E);
int EC_set_half(EC *E);
#ifdef MONTGOMERY
int EC_to_montgomery(EC *E, BN_MONTGOMERY *mont, BN_CTX *ctx);
int EC_from_montgomery(EC *E, BN_MONTGOMERY *mont, BN_CTX *ctx);
Expand Down
31 changes: 16 additions & 15 deletions crypto/ec/ec_point.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -157,7 +157,7 @@ EC_POINT *ECP_generate(BIGNUM *x, BIGNUM *z,EC *E, BN_CTX *ctx)
int Pnorm, Pinfty, X0, A0;

assert(E != NULL);
assert(E->A != NULL && E->B != NULL && E->p != NULL && E->h != NULL);
assert(E->A != NULL && E->B != NULL && E->p != NULL);

assert(ctx != NULL);

Expand Down Expand Up @@ -559,7 +559,7 @@ int ECP_double(EC_POINT *R, EC_POINT *P, EC *E, BN_CTX *ctx)
assert(R->X != NULL && R->Y != NULL && R->Z != NULL);

assert(E != NULL);
assert(E->A != NULL && E->B != NULL && E->p != NULL && E->h != NULL);
assert(E->A != NULL && E->B != NULL && E->p != NULL);

assert(ctx != NULL);

Expand Down Expand Up @@ -664,8 +664,7 @@ int ECP_add(EC_POINT *R, EC_POINT *P, EC_POINT *Q, EC *E, BN_CTX *ctx)
assert(R->X != NULL && R->Y != NULL && R->Z != NULL);

assert(E != NULL);
assert(E->A != NULL && E->B != NULL && E->p != NULL && E->h != NULL);
assert(!BN_is_zero(E->h));;
assert(E->A != NULL && E->B != NULL && E->p != NULL);

assert(ctx != NULL);

Expand Down Expand Up @@ -772,9 +771,10 @@ int ECP_add(EC_POINT *R, EC_POINT *P, EC_POINT *Q, EC *E, BN_CTX *ctx)
if (!BN_mod_mul(n5, n4, n5, p, ctx)) goto err;
if (!BN_mod_mul(n1, n2, n5, p, ctx)) goto err;
if (!BN_mod_sub(n0, n0, n1, p, ctx)) goto err;
if (!BN_mod_mul(R->Y, n0, E->h, p, ctx)) goto err; /* Y = (L6 * L9 - L8 * L5^3) / 2 */


if (BN_is_odd(n0))
if (!BN_add(n0, n0, p)) goto err;
/* now 0 <= n0 < 2*p, and n0 is even */
if (!BN_rshift1(R->Y, n0)) goto err; /* Y = (L6 * L9 - L8 * L5^3) / 2 */

#ifdef TEST
if (!ECP_is_on_ec(R, E, ctx)) return 0;
Expand Down Expand Up @@ -849,7 +849,7 @@ int ECP_multiply(EC_POINT *R, BIGNUM *k, ECP_PRECOMPUTE *prec, EC *E, BN_CTX *ct
assert(R->X != NULL && R->Y != NULL && R->Z != NULL);

assert(E != NULL);
assert(E->A != NULL && E->B != NULL && E->p != NULL && E->h != NULL);
assert(E->A != NULL && E->B != NULL && E->p != NULL);

assert(k != NULL);
assert(!k->neg);
Expand Down Expand Up @@ -1068,7 +1068,7 @@ int ECP_mont_double(EC_POINT *R, EC_POINT *P, EC *E, BN_MONTGOMERY *mont, BN_CTX
assert(R->X != NULL && R->Y != NULL && R->Z != NULL);

assert(E != NULL);
assert(E->A != NULL && E->B != NULL && E->p != NULL && E->h != NULL);
assert(E->A != NULL && E->B != NULL && E->p != NULL);

assert(ctx != NULL);

Expand Down Expand Up @@ -1153,8 +1153,7 @@ int ECP_mont_add(EC_POINT *R, EC_POINT *P, EC_POINT *Q, EC *E, BN_MONTGOMERY *mo
assert(R->X != NULL && R->Y != NULL && R->Z != NULL);

assert(E != NULL);
assert(E->A != NULL && E->B != NULL && E->p != NULL && E->h != NULL);
assert(!BN_is_zero(E->h));;
assert(E->A != NULL && E->B != NULL && E->p != NULL);

assert(ctx != NULL);

Expand Down Expand Up @@ -1252,8 +1251,10 @@ int ECP_mont_add(EC_POINT *R, EC_POINT *P, EC_POINT *Q, EC *E, BN_MONTGOMERY *mo
if (!BN_mont_mod_mul(n6, n4, n5, mont)) goto err;
if (!BN_mont_mod_mul(n1, n2, n6, mont)) goto err;
if (!BN_mod_sub_quick(n0, n0, n1, p)) goto err;
if (!BN_mont_mod_mul(R->Y, n0, E->h, mont)) goto err; /* Y = (L6 * L9 - L8 * L5^3) / 2 */

if (BN_is_odd(n0))
if (!BN_add(n0, n0, p)) goto err;
/* now 0 <= n0 < 2*p, and n0 is even */
if (!BN_rshift1(R->Y, n0)) goto err; /* Y = (L6 * L9 - L8 * L5^3) / 2 */

BN_CTX_end(ctx);
return 1;
Expand Down Expand Up @@ -1331,7 +1332,7 @@ int ECP_mont_multiply(EC_POINT *R, BIGNUM *k, ECP_PRECOMPUTE *prec, EC *E, BN_MO
assert(R->X != NULL && R->Y != NULL && R->Z != NULL);

assert(E != NULL);
assert(E->A != NULL && E->B != NULL && E->p != NULL && E->h != NULL);
assert(E->A != NULL && E->B != NULL && E->p != NULL);

assert(k != NULL);
assert(!k->neg);
Expand Down Expand Up @@ -1421,7 +1422,7 @@ int ECP_mont_multiply2(EC_POINT *R, BIGNUM *k, EC_POINT *P, EC *E, BN_MONTGOMERY
assert(P->X != NULL && P->Y != NULL && P->Z != NULL);

assert(E != NULL);
assert(E->A != NULL && E->B != NULL && E->p != NULL && E->h != NULL);
assert(E->A != NULL && E->B != NULL && E->p != NULL);

assert(k != NULL);
assert(!k->neg);
Expand Down

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