156 lines
3.4 KiB
Plaintext
156 lines
3.4 KiB
Plaintext
from sys import argv
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import sys
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import binascii
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import base64
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def binnahex(var):
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all = {"0000": "0",
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"0001": "1",
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"0010": "2",
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"0011": "3",
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"0100": "4",
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"0101": "5",
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"0110": "6",
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"0111": "7",
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"1000": "8",
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"1001": "9",
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"1010": "A",
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"1011": "B",
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"1100": "C",
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"1101": "D",
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"1110": "E",
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"1111": "F"
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}
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i = 0
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output = ""
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while (len(var) % 4 != 0):
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var = "0" + var
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while (i < len(var)):
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output = output + all[var[i:i + 4]]
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i = i + 4
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output = output.lstrip("0")
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output = "0" if len(output) == 0 else output
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return output
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#XOR
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def xor(a, b):
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# init
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result = []
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# porownuje znaki
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for i in range(1, len(b)):
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if a[i] == b[i]:
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result.append('0')
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else:
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result.append('1')
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return ''.join(result)
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# dzielenie modulo 2
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def divide(message):
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poly16 = "10001000000100001"
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# Ilosc bitow dla operacji XOR 'na raz'
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step = len(poly16)
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# podzial krok po kroku
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temp = message[0 : step]
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while step < len(message):
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if temp[0] == '1':
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temp = xor(poly16, temp) + message[step]
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else:
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# jezeli 1 bit po lewej == 0
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temp = xor('0'*step, temp) + message[step]
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# kolejny krok
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step += 1
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if temp[0] == '1':
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temp = xor(poly16, temp)
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else:
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temp = xor('0'*step, temp)
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check = temp
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return check
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def decode(message,crc):
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poly16 = "10001000000100001"
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l_poly16 = len(poly16)
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message = bytearray(message, 'ascii')
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message = format(int.from_bytes(message, "big"), "b")
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dec = int(crc, 16)
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crc2=bin(dec)[2:]
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msg=message+crc2
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while len(msg) % 8 != 0:
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msg = "0" + msg
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obroc = list(msg)
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for i in range(l_poly16 - 1):
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if obroc[i] == "0":
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obroc[i] = "1"
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elif obroc[i] == '1':
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obroc[i] = "0"
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msg = "".join(obroc)
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remainder = divide(msg)
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suma = 0
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for i in range(0, len(remainder)):
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if '1' in remainder:
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suma = suma+1
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if suma == 0:
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print("true ")
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elif suma > 0:
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print("false",remainder)
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def encode(message):
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poly16 = "10001000000100001"
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a=message
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message = bytearray(message, 'ascii')
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message = format(int.from_bytes(message, "big"), "b")
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l_poly16 = len(poly16)
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message = message + '0'*(l_poly16-1)
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while len(message) % 8 != 0:
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message = "0" + message
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obroc = list(message)
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for i in range(l_poly16 - 1):
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if obroc[i] == "0":
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obroc[i] = "1"
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elif obroc[i] == '1':
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obroc[i] = "0"
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message = "".join(obroc)
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remainder = divide(message)
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ab=binnahex(remainder)
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d=str(base64.b16decode(ab))[2:-1]
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message_final = a + d
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message_final = bytearray(message_final, 'ascii')
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d = bytearray(d, 'ascii')
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print("calosc : ", message_final)
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print("crc hex : ", ab)
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print("crc ascii : ", d)
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def main():
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global message
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message = list(argv[1])
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flag = argv[2]
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if flag == 'encode':
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encode(sys.argv[1])
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elif flag == 'decode':
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crc = argv[3]
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decode(sys.argv[1],sys.argv[3])
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if __name__ == '__main__':
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main()
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