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"""Tests for AES-256-GCM webcrypto variant."""
import os
import pytest
import blake3
from meshbay_common.crypto import generate_gek
from meshbay_common.webcrypto import chunk_key_aes, encrypt_chunk_aes, decrypt_chunk_aes
def test_aes_roundtrip():
gek = generate_gek()
data = os.urandom(1024 * 1024) # 1 MB
fh = blake3.blake3(data).digest()
key = chunk_key_aes(gek, fh, 0)
nonce, ct = encrypt_chunk_aes(key, data)
assert decrypt_chunk_aes(key, nonce, ct) == data
def test_aes_key_distinct_from_chacha_key():
"""AES and ChaCha20 keys for the same chunk must differ."""
from meshbay_common.crypto import chunk_key as chacha_key
gek = generate_gek()
data = os.urandom(100)
fh = blake3.blake3(data).digest()
aes_k = chunk_key_aes(gek, fh, 0)
chacha_k = chacha_key(gek, fh, 0)
assert aes_k != chacha_k
def test_aes_wrong_key_rejected():
gek = generate_gek()
data = b"private content"
fh = blake3.blake3(data).digest()
key = chunk_key_aes(gek, fh, 0)
nonce, ct = encrypt_chunk_aes(key, data)
wrong_key = chunk_key_aes(generate_gek(), fh, 0)
with pytest.raises(Exception):
decrypt_chunk_aes(wrong_key, nonce, ct)
def test_aes_chunk_keys_unique_per_chunk():
gek = generate_gek()
data = os.urandom(32)
fh = blake3.blake3(data).digest()
keys = {chunk_key_aes(gek, fh, i) for i in range(5)}
assert len(keys) == 5 # all distinct
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