312 lines
6.8 KiB
Python
312 lines
6.8 KiB
Python
import struct
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class Shannon:
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n = 16
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fold = n
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initkonst = 0x6996c53a
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keyp = 13
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r: list
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crc: list
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initr: list
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konst: int
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sbuf: int
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mbuf: int
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nbuf: int
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def __init__(self):
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self.r = [0 for _ in range(self.n)]
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self.crc = [0 for _ in range(self.n)]
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self.initr = [0 for _ in range(self.n)]
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def rotl(self, i: int, distance: int):
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return ((i << distance) | (i >> (32 - distance))) & 0xffffffff
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def sbox(self, i: int):
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i ^= self.rotl(i, 5) | self.rotl(i, 7)
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i ^= self.rotl(i, 19) | self.rotl(i, 22)
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return i
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def sbox2(self, i: int):
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i ^= self.rotl(i, 7) | self.rotl(i, 22)
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i ^= self.rotl(i, 5) | self.rotl(i, 19)
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return i
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def cycle(self):
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t: int
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t = self.r[12] ^ self.r[13] ^ self.konst
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t = self.sbox(t) ^ self.rotl(self.r[0], 1)
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for i in range(1, self.n):
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self.r[i - 1] = self.r[i]
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self.r[self.n - 1] = t
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t = self.sbox2(self.r[2] ^ self.r[15])
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self.r[0] ^= t
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self.sbuf = t ^ self.r[8] ^ self.r[12]
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def crc_func(self, i: int):
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t: int
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t = self.crc[0] ^ self.crc[2] ^ self.crc[15] ^ i
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for j in range(1, self.n):
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self.crc[j - 1] = self.crc[j]
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self.crc[self.n - 1] = t
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def mac_func(self, i: int):
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self.crc_func(i)
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self.r[self.keyp] ^= i
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def init_state(self):
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self.r[0] = 1
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self.r[1] = 1
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for i in range(2, self.n):
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self.r[i] = self.r[i - 1] + self.r[i - 2]
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self.konst = self.initkonst
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def save_state(self):
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for i in range(self.n):
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self.initr[i] = self.r[i]
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def reload_state(self):
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for i in range(self.n):
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self.r[i] = self.initr[i]
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def gen_konst(self):
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self.konst = self.r[0]
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def add_key(self, k: int):
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self.r[self.keyp] ^= k
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def diffuse(self):
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for i in range(self.fold):
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self.cycle()
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def load_key(self, key: bytes):
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extra = bytearray(4)
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i: int
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j: int
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t: int
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padding_size = int((len(key) + 3) / 4) * 4 - len(key)
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key = key + (b"\x00" * padding_size) + struct.pack("<I", len(key))
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for i in range(0, len(key), 4):
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self.r[self.keyp] = \
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self.r[self.keyp] ^ \
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struct.unpack("<I", key[i: i + 4])[0]
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self.cycle()
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for i in range(self.n):
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self.crc[i] = self.r[i]
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self.diffuse()
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for i in range(self.n):
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self.r[i] ^= self.crc[i]
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def key(self, key: bytes):
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self.init_state()
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self.load_key(key)
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self.gen_konst()
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self.save_state()
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self.nbuf = 0
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def nonce(self, nonce: bytes):
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self.reload_state()
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self.konst = self.initkonst
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self.load_key(nonce)
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self.gen_konst()
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self.nbuf = 0
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def encrypt(self, buffer: bytes, n: int = None):
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if n is None:
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return self.encrypt(buffer, len(buffer))
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buffer = bytearray(buffer)
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i = 0
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j: int
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t: int
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if self.nbuf != 0:
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while self.nbuf != 0 and n != 0:
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self.mbuf ^= (buffer[i] & 0xff) << (32 - self.nbuf)
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buffer[i] ^= (self.sbuf >> (32 - self.nbuf)) & 0xff
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i += 1
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self.nbuf -= 8
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n -= 1
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if self.nbuf != 0:
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return
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self.mac_func(self.mbuf)
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j = n & ~0x03
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while i < j:
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self.cycle()
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t = ((buffer[i + 3] & 0xFF) << 24) | \
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((buffer[i + 2] & 0xFF) << 16) | \
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((buffer[i + 1] & 0xFF) << 8) | \
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(buffer[i] & 0xFF)
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self.mac_func(t)
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t ^= self.sbuf
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buffer[i + 3] = (t >> 24) & 0xFF
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buffer[i + 2] = (t >> 16) & 0xFF
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buffer[i + 3] = (t >> 8) & 0xFF
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buffer[i] = t & 0xFF
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i += 4
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n &= 0x03
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if n != 0:
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self.cycle()
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self.mbuf = 0
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self.nbuf = 32
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while self.nbuf != 0 and n != 0:
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self.mbuf ^= (buffer[i] & 0xff) << (32 - self.nbuf)
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buffer[i] ^= (self.sbuf >> (32 - self.nbuf)) & 0xff
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i += 1
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self.nbuf -= 8
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n -= 1
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return bytes(buffer)
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def decrypt(self, buffer: bytes, n: int = None):
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if n is None:
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return self.decrypt(buffer, len(buffer))
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buffer = bytearray(buffer)
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i = 0
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j: int
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t: int
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if self.nbuf != 0:
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while self.nbuf != 0 and n != 0:
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buffer[i] ^= (self.sbuf >> (32 - self.nbuf)) & 0xff
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self.mbuf ^= (buffer[i] & 0xff) << (32 - self.nbuf)
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i += 1
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self.nbuf -= 8
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n -= 1
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if self.nbuf != 0:
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return
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self.mac_func(self.mbuf)
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j = n & ~0x03
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while i < j:
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self.cycle()
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t = ((buffer[i + 3] & 0xFF) << 24) | \
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((buffer[i + 2] & 0xFF) << 16) | \
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((buffer[i + 1] & 0xFF) << 8) | \
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(buffer[i] & 0xFF)
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t ^= self.sbuf
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self.mac_func(t)
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buffer[i + 3] = (t >> 24) & 0xFF
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buffer[i + 2] = (t >> 16) & 0xFF
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buffer[i + 1] = (t >> 8) & 0xFF
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buffer[i] = t & 0xFF
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i += 4
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n &= 0x03
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if n != 0:
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self.cycle()
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self.mbuf = 0
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self.nbuf = 32
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while self.nbuf != 0 and n != 0:
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buffer[i] ^= (self.sbuf >> (32 - self.nbuf)) & 0xff
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self.mbuf ^= (buffer[i] & 0xff) << (32 - self.nbuf)
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i += 1
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self.nbuf -= 8
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n -= 1
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return bytes(buffer)
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def finish(self, buffer: bytes, n: int = None):
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if n is None:
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return self.finish(buffer, len(buffer))
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buffer = bytearray(buffer)
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i = 0
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j: int
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if self.nbuf != 0:
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self.mac_func(self.mbuf)
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self.cycle()
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self.add_key(self.initkonst ^ (self.nbuf << 3))
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self.nbuf = 0
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for j in range(self.n):
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self.r[j] ^= self.crc[j]
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self.diffuse()
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while n > 0:
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self.cycle()
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if n >= 4:
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buffer[i + 3] = (self.sbuf >> 24) & 0xff
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buffer[i + 2] = (self.sbuf >> 16) & 0xff
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buffer[i + 1] = (self.sbuf >> 8) & 0xff
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buffer[i] = self.sbuf & 0xff
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n -= 4
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i += 4
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else:
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for j in range(n):
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buffer[i + j] = (self.sbuf >> (i * 8)) & 0xff
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break
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return bytes(buffer)
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