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Make ec_GFp_simple_point_get_affine_coordinates() faster

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for Montgomery representations.

Submitted by: Sheueling Chang, Bodo Moeller
This commit is contained in:
Bodo Möller 2002-11-20 10:53:33 +00:00
parent 6a8afe2201
commit 137445140b
1 changed files with 26 additions and 25 deletions
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51
crypto/ec/ecp_smpl.c
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@ -505,8 +505,8 @@ int ec_GFp_simple_point_get_affine_coordinates(const EC_GROUP *group, const EC_P
BIGNUM *x, BIGNUM *y, BN_CTX *ctx) BIGNUM *x, BIGNUM *y, BN_CTX *ctx)
{ {
BN_CTX *new_ctx = NULL; BN_CTX *new_ctx = NULL;
BIGNUM *X, *Y, *Z, *Z_1, *Z_2, *Z_3; BIGNUM *Z, *Z_1, *Z_2, *Z_3;
const BIGNUM *X_, *Y_, *Z_; const BIGNUM *Z_;
int ret = 0; int ret = 0;
if (EC_POINT_is_at_infinity(group, point)) if (EC_POINT_is_at_infinity(group, point))
@ -523,8 +523,6 @@ int ec_GFp_simple_point_get_affine_coordinates(const EC_GROUP *group, const EC_P
} }
BN_CTX_start(ctx); BN_CTX_start(ctx);
X = BN_CTX_get(ctx);
Y = BN_CTX_get(ctx);
Z = BN_CTX_get(ctx); Z = BN_CTX_get(ctx);
Z_1 = BN_CTX_get(ctx); Z_1 = BN_CTX_get(ctx);
Z_2 = BN_CTX_get(ctx); Z_2 = BN_CTX_get(ctx);
@ -535,27 +533,37 @@ int ec_GFp_simple_point_get_affine_coordinates(const EC_GROUP *group, const EC_P
if (group->meth->field_decode) if (group->meth->field_decode)
{ {
if (!group->meth->field_decode(group, X, &point->X, ctx)) goto err;
if (!group->meth->field_decode(group, Y, &point->Y, ctx)) goto err;
if (!group->meth->field_decode(group, Z, &point->Z, ctx)) goto err; if (!group->meth->field_decode(group, Z, &point->Z, ctx)) goto err;
X_ = X; Y_ = Y; Z_ = Z; Z_ = Z;
} }
else else
{ {
X_ = &point->X;
Y_ = &point->Y;
Z_ = &point->Z; Z_ = &point->Z;
} }
if (BN_is_one(Z_)) if (BN_is_one(Z_))
{ {
if (x != NULL) if (group->meth->field_decode)
{ {
if (!BN_copy(x, X_)) goto err; if (x != NULL)
{
if (!group->meth->field_decode(group, x, &point->X, ctx)) goto err;
}
if (y != NULL)
{
if (!group->meth->field_decode(group, y, &point->Y, ctx)) goto err;
}
} }
if (y != NULL) else
{ {
if (!BN_copy(y, Y_)) goto err; if (x != NULL)
{
if (!BN_copy(x, &point->X)) goto err;
}
if (y != NULL)
{
if (!BN_copy(y, &point->Y)) goto err;
}
} }
} }
else else
@ -578,15 +586,8 @@ int ec_GFp_simple_point_get_affine_coordinates(const EC_GROUP *group, const EC_P
if (x != NULL) if (x != NULL)
{ {
if (group->meth->field_encode == 0) /* in the Montgomery case, field_mul will cancel out Montgomery factor in X: */
{ if (!group->meth->field_mul(group, x, &point->X, Z_2, ctx)) goto err;
/* field_mul works on standard representation */
if (!group->meth->field_mul(group, x, X_, Z_2, ctx)) goto err;
}
else
{
if (!BN_mod_mul(x, X_, Z_2, &group->field, ctx)) goto err;
}
} }
if (y != NULL) if (y != NULL)
@ -595,14 +596,14 @@ int ec_GFp_simple_point_get_affine_coordinates(const EC_GROUP *group, const EC_P
{ {
/* field_mul works on standard representation */ /* field_mul works on standard representation */
if (!group->meth->field_mul(group, Z_3, Z_2, Z_1, ctx)) goto err; if (!group->meth->field_mul(group, Z_3, Z_2, Z_1, ctx)) goto err;
if (!group->meth->field_mul(group, y, Y_, Z_3, ctx)) goto err;
} }
else else
{ {
if (!BN_mod_mul(Z_3, Z_2, Z_1, &group->field, ctx)) goto err; if (!BN_mod_mul(Z_3, Z_2, Z_1, &group->field, ctx)) goto err;
if (!BN_mod_mul(y, Y_, Z_3, &group->field, ctx)) goto err;
} }
/* in the Montgomery case, field_mul will cancel out Montgomery factor in Y: */
if (!group->meth->field_mul(group, y, &point->Y, Z_3, ctx)) goto err;
} }
} }