def hkdf_sha256_32(ikm: bytes, salt: bytes, info: bytes) -> bytes:
if HAS_CRYPTODOME:
return CD_HKDF(ikm, 32, salt, CD_SHA256, context=info)
if HAS_CRYPTOGRAPHY:
return CG_HKDF(algorithm=CG_SHA256(),
length=32,
salt=salt,
info=info,
backend=CG_default_backend()).derive(ikm)
raise Exception("no hkdf backend found")
def aes_encrypt_with_iv(key: bytes, iv: bytes, data: bytes) -> bytes:
assert_bytes(key, iv, data)
data = append_PKCS7_padding(data)
if HAS_CRYPTODOME:
e = CD_AES.new(key, CD_AES.MODE_CBC, iv).encrypt(data)
elif HAS_CRYPTOGRAPHY:
cipher = CG_Cipher(CG_algorithms.AES(key), CG_modes.CBC(iv), backend=CG_default_backend())
encryptor = cipher.encryptor()
e = encryptor.update(data) + encryptor.finalize()
else:
aes_cbc = pyaes.AESModeOfOperationCBC(key, iv=iv)
aes = pyaes.Encrypter(aes_cbc, padding=pyaes.PADDING_NONE)
e = aes.feed(data) + aes.feed() # empty aes.feed() flushes buffer
return e
def chacha20_encrypt(*, key: bytes, nonce: bytes, data: bytes) -> bytes:
assert isinstance(key, (bytes, bytearray))
assert isinstance(nonce, (bytes, bytearray))
assert isinstance(data, (bytes, bytearray))
assert len(nonce) == 8, f"unexpected nonce size: {len(nonce)} (expected: 8)"
if HAS_CRYPTODOME:
cipher = CD_ChaCha20.new(key=key, nonce=nonce)
return cipher.encrypt(data)
if HAS_CRYPTOGRAPHY:
nonce = bytes(8) + nonce # cryptography wants 16 byte nonces
algo = CG_algorithms.ChaCha20(key=key, nonce=nonce)
cipher = CG_Cipher(algo, mode=None, backend=CG_default_backend())
encryptor = cipher.encryptor()
return encryptor.update(data)
raise Exception("no chacha20 backend found")
def aes_decrypt_with_iv(key: bytes, iv: bytes, data: bytes) -> bytes:
assert_bytes(key, iv, data)
if HAS_CRYPTODOME:
cipher = CD_AES.new(key, CD_AES.MODE_CBC, iv)
data = cipher.decrypt(data)
elif HAS_CRYPTOGRAPHY:
cipher = CG_Cipher(CG_algorithms.AES(key), CG_modes.CBC(iv), backend=CG_default_backend())
decryptor = cipher.decryptor()
data = decryptor.update(data) + decryptor.finalize()
else:
aes_cbc = pyaes.AESModeOfOperationCBC(key, iv=iv)
aes = pyaes.Decrypter(aes_cbc, padding=pyaes.PADDING_NONE)
data = aes.feed(data) + aes.feed() # empty aes.feed() flushes buffer
try:
return strip_PKCS7_padding(data)
except InvalidPadding:
raise InvalidPassword()