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from typing import List
from noiseprotocol.constants import TOKEN_PSK
class Pattern(object):
"""
TODO document
"""
def __init__(self):
# As per specification, if both parties have pre-messages, the initiator is listed first. To reduce complexity,
# pre_messages shall be a list of two lists:
# the first for the initiator's pre-messages, the second for the responder
self.pre_messages = [
[],
[]
]
# List of lists of valid tokens, alternating between tokens for initiator and responder
self.tokens = []
self.name = ''
self.one_way = False
self.psk_count = 0
def has_pre_messages(self):
return any(map(lambda x: len(x) > 0, self.pre_messages))
def get_initiator_pre_messages(self) -> list:
return self.pre_messages[0].copy()
def get_responder_pre_messages(self) -> list:
return self.pre_messages[1].copy()
def apply_pattern_modifiers(self, modifiers: List[str]) -> None:
# Applies given pattern modifiers to self.tokens of the Pattern instance.
for modifier in modifiers:
if modifier.startswith('psk'):
try:
index = int(modifier.replace('psk', '', 1))
except ValueError:
raise ValueError('Improper psk modifier {}'.format(modifier))
if index // 2 > len(self.tokens):
raise ValueError('Modifier {} cannot be applied - pattern has not enough messages'.format(modifier))
# Add TOKEN_PSK in the correct place in the correct message
if index == 0: # if 0, insert at the beginning of first message
self.tokens[0].insert(0, TOKEN_PSK)
else: # if bigger than zero, append at the end of first, second etc.
self.tokens[index - 1].append(TOKEN_PSK)
self.psk_count += 1
elif modifier == 'fallback':
raise NotImplementedError # TODO implement
else:
raise ValueError('Unknown pattern modifier {}'.format(modifier))
def get_required_keypairs(self, initiator: bool) -> list:
required = []
if initiator:
if self.name[0] in ('K', 'X', 'I'):
required.append('s')
if self.one_way or self.name[1] == 'K':
required.append('rs')
else:
if self.name[0] == 'K':
required.append('rs')
if self.one_way or self.name[1] in ['K', 'X']:
required.append('s')
return required
class OneWayPattern(Pattern):
def __init__(self):
super(OneWayPattern, self).__init__()
self.one_way = True
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