def test_public_params_derive(bits, key):
length = FFI.sizeof("struct umash_params")
umash_key = b"Do not use UMASH VS adversaries."
if key is not None:
umash_key = key
nonce = struct.pack("<Q", bits)
expected = FFI.new("struct umash_params[1]")
salsa_bytes = Salsa20.new(umash_key, nonce).encrypt(b"\x00" * length)
FFI.memmove(expected, salsa_bytes, length)
assert C.umash_params_prepare(expected)
actual = FFI.new("struct umash_params[1]")
if key is None:
C.umash_params_derive(actual, bits, FFI.NULL)
else:
buf = FFI.new("char[]", len(key))
FFI.memmove(buf, key, len(key))
C.umash_params_derive(actual, bits, buf)
# The values should all be the same.
assert length % 8 == 0
for i in range(length // 8):
assert FFI.cast("uint64_t *",
actual)[i] == FFI.cast("uint64_t *", expected)[i]
def assert_idempotent(params):
"""Asserts that calling `umash_params_prepare` on something that was
successfully prepared is idempotent.
"""
size = FFI.sizeof("struct umash_params")
copy = FFI.new("struct umash_params[1]")
FFI.memmove(copy, params, size)
assert C.umash_params_prepare(copy) == True
# The copy should still be the same as params.
assert size % 8 == 0
for i in range(size // 8):
assert FFI.cast("uint64_t *",
params)[i] == FFI.cast("uint64_t *", copy)[i]
def test_public_smoke_matches(random, seed, data):
"""Prepare a params struct, and make sure the UMASH function matches
our reference."""
params = FFI.new("struct umash_params[1]")
size = FFI.sizeof("struct umash_params")
assert size % 8 == 0
for i in range(size // 8):
FFI.cast("uint64_t *", params)[i] = random.getrandbits(64)
# Pseudorandom input should always succeed.
assert C.umash_params_prepare(params) == True
assert_idempotent(params)
expected0 = umash(
UmashKey(params[0].poly[0][1],
[params[0].oh[i] for i in range(OH_COUNT)]),
seed,
data,
secondary=False,
)
assert C.umash_full(params, seed, 0, data, len(data)) == expected0
expected1 = umash(
UmashKey(
params[0].poly[1][1],
[params[0].oh[i] for i in range(OH_COUNT)],
),
seed,
data,
secondary=True,
)
assert C.umash_full(params, seed, 1, data, len(data)) == expected1
