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wolfSSL: Speed up crypto_ec_point_compute_y_sqr()

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Optimize the calculation by computing (x^2 + a) first to get rid of one
separate multiplication by x.

Signed-off-by: Jouni Malinen <j@w1.fi>
This commit is contained in:
Jouni Malinen 2022-04-23 16:12:49 +03:00
parent f50d5c9a83
commit 08d7738bb2
1 changed files with 3 additions and 5 deletions
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8
src/crypto/crypto_wolfssl.c
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@ -1650,25 +1650,23 @@ struct crypto_bignum *
crypto_ec_point_compute_y_sqr(struct crypto_ec *e,
const struct crypto_bignum *x)
{
mp_int *y2, t;
mp_int *y2;
if (TEST_FAIL())
return NULL;
/* y^2 = x^3 + ax + b = (x^2 + a)x + b */
y2 = (mp_int *) crypto_bignum_init();
if (!y2 ||
mp_init(&t) != MP_OKAY ||
mp_sqrmod((mp_int *) x, &e->prime, y2) != 0 ||
mp_addmod(y2, &e->a, &e->prime, y2) != 0 ||
mp_mulmod((mp_int *) x, y2, &e->prime, y2) != 0 ||
mp_mulmod((mp_int *) x, &e->a, &e->prime, &t) != 0 ||
mp_addmod(y2, &t, &e->prime, y2) != 0 ||
mp_addmod(y2, &e->b, &e->prime, y2) != 0) {
mp_clear(y2);
os_free(y2);
y2 = NULL;
}
mp_clear(&t);
return (struct crypto_bignum *) y2;
}