void test_sqrt(const secp256k1_fe_t *a, const secp256k1_fe_t *k) {
secp256k1_fe_t r1, r2;
int v = secp256k1_fe_sqrt(&r1, a);
CHECK((v == 0) == (k == NULL));
if (k != NULL) {
/* Check that the returned root is +/- the given known answer */
secp256k1_fe_negate(&r2, &r1, 1);
secp256k1_fe_add(&r1, k); secp256k1_fe_add(&r2, k);
secp256k1_fe_normalize(&r1); secp256k1_fe_normalize(&r2);
CHECK(secp256k1_fe_is_zero(&r1) || secp256k1_fe_is_zero(&r2));
}
}
void random_fe_non_zero(secp256k1_fe_t *nz) {
int tries = 10;
while (--tries >= 0) {
random_fe(nz);
secp256k1_fe_normalize(nz);
if (!secp256k1_fe_is_zero(nz))
break;
}
/* Infinitesimal probability of spurious failure here */
CHECK(tries >= 0);
}
void random_group_element_jacobian_test(secp256k1_gej_t *gej, const secp256k1_ge_t *ge) {
do {
random_field_element_test(&gej->z);
if (!secp256k1_fe_is_zero(&gej->z)) {
break;
}
} while(1);
secp256k1_fe_t z2; secp256k1_fe_sqr(&z2, &gej->z);
secp256k1_fe_t z3; secp256k1_fe_mul(&z3, &z2, &gej->z);
secp256k1_fe_mul(&gej->x, &ge->x, &z2);
secp256k1_fe_mul(&gej->y, &ge->y, &z3);
gej->infinity = ge->infinity;
}
static int secp256k1_pubkey_load(const secp256k1_context* ctx, secp256k1_ge* ge, const secp256k1_pubkey* pubkey) {
if (sizeof(secp256k1_ge_storage) == 64) {
/* When the secp256k1_ge_storage type is exactly 64 byte, use its
* representation inside secp256k1_pubkey, as conversion is very fast.
* Note that secp256k1_pubkey_save must use the same representation. */
secp256k1_ge_storage s;
memcpy(&s, &pubkey->data[0], sizeof(s));
secp256k1_ge_from_storage(ge, &s);
} else {
/* Otherwise, fall back to 32-byte big endian for X and Y. */
secp256k1_fe x, y;
secp256k1_fe_set_b32(&x, pubkey->data);
secp256k1_fe_set_b32(&y, pubkey->data + 32);
secp256k1_ge_set_xy(ge, &x, &y);
}
ARG_CHECK(!secp256k1_fe_is_zero(&ge->x));
return 1;
}