core_ed25519_is_valid_point: check Y==Z in addition to X==0

This commit is contained in:
Frank Denis
2025-12-30 12:00:08 +01:00
parent 4f5e89fa84
commit 5106e05223
2 changed files with 6 additions and 2 deletions
@@ -992,10 +992,13 @@ int
ge25519_is_on_main_subgroup(const ge25519_p3 *p)
{
ge25519_p3 pl;
fe25519 t;
ge25519_mul_l(&pl, p);
return fe25519_iszero(pl.X);
fe25519_sub(t, pl.Y, pl.Z);
return fe25519_iszero(pl.X) & fe25519_iszero(t);
}
int
+2 -1
View File
@@ -130,11 +130,12 @@ main(void)
assert(crypto_core_ed25519_is_valid_point(p) == 0);
p[0] = 9;
assert(crypto_core_ed25519_is_valid_point(p) == 1);
assert(crypto_core_ed25519_is_valid_point(p) == 0);
assert(crypto_core_ed25519_is_valid_point(max_canonical_p) == 1);
assert(crypto_core_ed25519_is_valid_point(non_canonical_invalid_p) == 0);
assert(crypto_core_ed25519_is_valid_point(non_canonical_p) == 0);
assert(crypto_core_ed25519_is_valid_point(not_main_subgroup_p) == 0);
memcpy(p2, p, crypto_core_ed25519_BYTES);
add_P(p2);