def cipher_key(self,
sender: ID,
receiver: ID,
generate: bool = False) -> Optional[SymmetricKey]:
if receiver.is_broadcast:
return SymmetricKey.generate(algorithm=PlainKey.PLAIN)
# get key from cache
key = self.__cipher_key(sender, receiver)
if key is None and generate:
key = SymmetricKey.generate(algorithm=SymmetricKey.AES)
self.__cache_cipher_key(key=key, sender=sender, receiver=receiver)
return key
def cipher_key(self,
sender: ID,
receiver: ID,
generate: bool = False) -> Optional[SymmetricKey]:
if receiver.is_broadcast:
return plain_key
# get key from cache
key = self.__cipher_key(sender, receiver)
if key is None and generate:
# generate and cache it
key = SymmetricKey.generate(algorithm=SymmetricKey.AES)
assert key is not None, 'failed to generate key'
self.cache_cipher_key(key=key, sender=sender, receiver=receiver)
return key