83 lines
2.4 KiB
Python
Executable File
83 lines
2.4 KiB
Python
Executable File
#!/usr/bin/env python3
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# -*- coding: utf-8 -*-
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from functools import reduce
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from itertools import product
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CHARSET = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXY'
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def safe2real(code: str):
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"""Converts a code with unambiguous characters to the real code"""
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code = code.upper()
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code = code.replace('V', 'A') # A might be confused with 4
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code = code.replace('W', 'E') # E might be confused with 3
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code = code.replace('X', 'I') # I might be confused with 1
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code = code.replace('Y', 'O') # O might be confused with 0
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return code
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def generateChecksum(base_code):
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if len(base_code) != 15:
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raise RuntimeError("Bad argument to checksum")
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# Mystery/bug: Why is this ord('7') in particular? 55, 0o55 and 0x55 are all unrelated to anything in base 33. The check looks like it's trying to do c - 'A', but does the weirdest thing instead.
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cksum = reduce(lambda cksum, c: (cksum + (ord(c) - ord('0') if ord(c) <= ord('9') else ord(c) - ord('7'))) % 33, base_code, 0)
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return CHARSET[cksum]
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def validate(code):
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if len(code) != 16: return False
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theirs = code[15]
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mine = generateChecksum(code[0:15])
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return (theirs == mine)
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def get_type(code: str) -> str:
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if code[0].isnumeric():
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return 'NUM'
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elif code[0] == 'A':
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return '_A_'
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elif code[0] == 'B':
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return '_B_'
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elif code[0] == 'C':
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return '_C_'
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else:
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return 'UNK'
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if __name__ == '__main__':
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import sys
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args = None
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if len(sys.argv) == 1:
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print("Syntax: {} [A0...]".format(sys.argv[0]))
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print(" replace unidentified characters with *")
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sys.exit(1)
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code = sys.argv[1]
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if len(code) != 16:
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print("Code must be exactly 16 characters long.")
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sys.exit(2)
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if get_type(code) != '_A_':
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print("Code must be starting with 'A'!")
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sys.exit(3)
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real_code = safe2real(code)
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print("Actual code: {}".format(real_code))
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unknowns = 0
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for c in real_code:
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if c == '*':
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unknowns += 1
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if unknowns == 0:
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print("No unknown digits. Nothing to do.")
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sys.exit(4)
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print("{} unknown digits. {} combinations.".format(unknowns, len(CHARSET)**unknowns))
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print("Valid codes:")
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repstring = real_code.replace("*", "{}")
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for p in product(CHARSET, repeat=unknowns):
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test_code = repstring.format(*p)
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isvalid = validate(test_code)
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if isvalid:
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print(test_code)
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