def __init__(self,
peer_key: x25519.X25519PublicKey,
my_private_key: x25519.X25519PrivateKey = None,
min_peer_tag_len: int = MAX_TAG_LEN):
"""Initialize Glome class.
Performs the handshake and generates keys.
Args:
peer_key: Your peer's public key.
my_private_key: Your private key.
min_peer_tag_len: Desired length (in bytes) for the tag.
Must be an integer in range 1-32.
Raises:
ValueError: Raised whenever min_peer_tag_len is not in range 1-32.
ExchangeError: Raised whenever null shared secret is derived from
user/peer key pair.
"""
if my_private_key is None:
my_private_key, my_public_key = generate_keys()
else:
my_public_key = my_private_key.public_key()
if not Glome.MIN_TAG_LEN < min_peer_tag_len <= Glome.MAX_TAG_LEN:
raise ValueError('min_peer_tag_len must be in range {}-{}'.format(
Glome.MIN_TAG_LEN, Glome.MAX_TAG_LEN))
try:
shared_secret = my_private_key.exchange(peer_key)
except ValueError as value_error:
raise ExchangeError(
'Failed to deduce shared secret') from value_error
self._send_key = shared_secret + _public_key_encode(
peer_key) + _public_key_encode(my_public_key)
self._receive_key = shared_secret + _public_key_encode(
my_public_key) + _public_key_encode(peer_key)
self._peer_key = peer_key
self._my_keys = KeyPair(my_private_key, my_public_key)
self._min_peer_tag_len = min_peer_tag_len
def encode_publickey(key: x25519.X25519PrivateKey) -> str:
return b64encode(key.public_key().public_bytes(
encoding=serialization.Encoding.Raw,
format=serialization.PublicFormat.Raw)).decode("ascii")
