rana-cli/wakatime/packages/ntlm_auth/rc4.py
2017-02-15 15:02:05 -08:00

51 lines
1.9 KiB
Python

# This library is free software: you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation, either
# version 3 of the License, or (at your option) any later version.
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
# You should have received a copy of the GNU Lesser General Public
# License along with this library. If not, see <http://www.gnu.org/licenses/> or <http://www.gnu.org/licenses/lgpl.txt>.
class ARC4(object):
state = None
i = 0
j = 0
def __init__(self, key):
# Split up the key into a list
if isinstance(key, str):
key = [ord(c) for c in key]
else:
key = [c for c in key]
#Key-scheduling algorithm (KSA)
self.state = [n for n in range(256)]
j = 0
for i in range(256):
j = (j + self.state[i] + key[i % len(key)]) % 256
self.state[i], self.state[j] = self.state[j], self.state[i]
def update(self, value):
chars = []
random_gen = self._random_generator()
for char in value:
if isinstance(value, str):
byte = ord(char)
else:
byte = char
updated_byte = byte ^ next(random_gen)
chars.append(updated_byte)
return bytes(bytearray(chars))
def _random_generator(self):
#Pseudo-Random Generation Algorithm (PRGA)
while True:
self.i = (self.i + 1) % 256
self.j = (self.j + self.state[self.i]) % 256
self.state[self.i], self.state[self.j] = self.state[self.j], self.state[self.i]
yield self.state[(self.state[self.i] + self.state[self.j]) % 256]