def test_splitting(self) -> None:
test_string = b'cypherpunk'
self.assertEqual(
split_to_substrings(test_string, length=5),
[b'cyphe', b'ypher', b'pherp', b'herpu', b'erpun', b'rpunk'])
self.assertEqual(split_to_substrings(test_string, length=7),
[b'cypherp', b'ypherpu', b'pherpun', b'herpunk'])
self.assertEqual(
split_to_substrings(test_string, length=len(test_string)),
[b'cypherpunk'])
self.assertEqual(
split_to_substrings(test_string, length=len(test_string) + 1), [])
def exchange_public_keys(
onion_pub_key: bytes,
tfc_public_key_user: bytes,
kdk_hash: bytes,
contact: 'Contact',
settings: 'Settings',
queues: 'QueueDict',
) -> bytes:
"""Exchange public keys with contact.
This function outputs the user's public key and waits for user to
enter the public key of the contact. If the User presses <Enter>,
the function will resend the users' public key to contact.
"""
public_key_packet = PUBLIC_KEY_DATAGRAM_HEADER + onion_pub_key + tfc_public_key_user
queue_to_nc(public_key_packet, queues[RELAY_PACKET_QUEUE])
while True:
try:
tfc_public_key_contact = get_b58_key(B58_PUBLIC_KEY, settings,
contact.short_address)
except ValueError as invalid_pub_key:
invalid_key = str(invalid_pub_key).encode()
# Do not send packet to Relay Program if the user has for some reason
# managed to embed the local key decryption key inside the public key.
substrings = split_to_substrings(invalid_key,
ENCODED_B58_KDK_LENGTH)
safe_string = not any(
blake2b(substring) == kdk_hash for substring in substrings)
if safe_string:
public_key_packet = (UNENCRYPTED_DATAGRAM_HEADER +
UNENCRYPTED_PUBKEY_CHECK + onion_pub_key +
invalid_key)
queue_to_nc(public_key_packet, queues[RELAY_PACKET_QUEUE])
continue
if tfc_public_key_contact == b'':
public_key_packet = PUBLIC_KEY_DATAGRAM_HEADER + onion_pub_key + tfc_public_key_user
queue_to_nc(public_key_packet, queues[RELAY_PACKET_QUEUE])
continue
return tfc_public_key_contact