102 lines
2.2 KiB
Python
102 lines
2.2 KiB
Python
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#!/usr/bin/env nix-shell
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#!nix-shell -i python -p python3
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# NOTE: the colors are used to keep track of which letters have been
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# already substituted, and which are still unknown.
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def green(s):
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return f"\033[42m{s}\033[0m"
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def red(s):
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return f"\033[41m{s}\033[0m"
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def substitute(cipher_text, substitution_map):
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for letter in cipher_text:
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if letter.lower() in substitution_map:
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if letter.isupper():
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x = substitution_map[letter.lower()].upper()
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else:
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x = substitution_map[letter]
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print(green(x), end="")
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else:
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print(red(letter), end="")
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with open('message.txt', 'r') as file:
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enc = file.read()
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# Here, I will be slowly substituting the letters in the ciphertext
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# based on what I believe the words to be. I have commented out the
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# invocations of substitute, and commented the newly found letters
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# after each invocation.
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# Starting off, "wex dqar bg: cbzjZWD{...}" looks like "the flag is: picoCTF{...}"
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substitution_map = {
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'0': '0',
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'1': '1',
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'2': '2',
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'3': '3',
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'4': '4',
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'5': '5',
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'6': '6',
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'7': '7',
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'8': '8',
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'9': '9',
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'-': '-',
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'_': '_',
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'\n': '\n',
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' ': ' ',
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',': ',',
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'.': '.',
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':': ':',
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';': ';',
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'{': '{',
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'}': '}',
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'(': '(',
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')': ')',
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'w': 't',
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'e': 'h',
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'x': 'e',
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'd': 'f',
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'q': 'l',
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'a': 'a',
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'r': 'g',
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'b': 'i',
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'g': 's',
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'c': 'p',
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'z': 'c',
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'j': 'o',
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}
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# substitute(enc, substitution_map)
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# '(shoft fof captpfe the flag) afe a tspe' -> '(short for capture the flag) are a type'
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# 'coipetitiov' -> 'competition'
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substitution_map['f'] = 'r'
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substitution_map['p'] = 'u'
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substitution_map['s'] = 'y'
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substitution_map['i'] = 'm'
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substitution_map['v'] = 'n'
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# substitute(enc, substitution_map)
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# 'presentem hith' -> 'presented with'
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# 'numter' -> 'number'
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# 'security snills' -> 'security skills'
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substitution_map['m'] = 'd'
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substitution_map['h'] = 'w'
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substitution_map['t'] = 'b'
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substitution_map['n'] = 'k'
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# substitute(enc, substitution_map)
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# 'seryice' -> 'service'
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# 'FR3LU3NCY' -> 'FR3QU3NCY'
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substitution_map['y'] = 'v'
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substitution_map['l'] = 'q'
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substitute(enc, substitution_map)
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