37 lines
1.0 KiB
Python
37 lines
1.0 KiB
Python
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#!/usr/bin/env python3
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import string
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LOWERCASE_OFFSET = ord("a")
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ALPHABET = string.ascii_lowercase[:16]
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flag = "mlnklfnknljflfjljnjijjmmjkmljnjhmhjgjnjjjmmkjjmijhmkjhjpmkmkmljkjijnjpmhmjjgjj"
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def b16_decode(enc):
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dec = ""
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for i in range(0, len(enc), 2):
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first = "{0:04b}".format(ALPHABET.index(enc[i]))
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second = "{0:04b}".format(ALPHABET.index(enc[i + 1]))
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dec += chr(int(first + second, 2))
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return dec
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def unshift(c, k):
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t1 = ord(c) - LOWERCASE_OFFSET
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t2 = ord(k) - LOWERCASE_OFFSET
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return ALPHABET[(t1 - t2) % len(ALPHABET)]
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def main():
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for key in ALPHABET:
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unenc = ""
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for i, c in enumerate(flag):
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unenc += unshift(c, key[i % len(key)])
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unshifted = ''.join(unshift(c, key) for c in flag)
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# NOTE: key is 'g', "et tu?" is a caesar reference.
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# Remove the if statement to see all outpus for all keys
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if key == 'g':
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print(f'picoCTF{{{b16_decode(unenc)}}}')
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if __name__ == "__main__":
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main()
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