28 lines
625 B
Python
28 lines
625 B
Python
import os
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BITS = 56
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FLAG = os.getenv("FLAG", "CSCG{TESTFLAG}")
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A = int.from_bytes(os.urandom(BITS//8), "little")
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B = int.from_bytes(os.urandom(BITS//8), "little")
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SEED = int.from_bytes(os.urandom(BITS//8), "little")
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def rng(x, size):
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return (x*A+B) & ((2**size)-1)
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def gen_random(seed, bits, mask):
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state = seed
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while True:
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state = rng(state, bits)
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yield state & mask
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def main():
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print("Here are some random numbers, now guess the flag")
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rng = gen_random(SEED, BITS, 0xFF)
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for i in range(len(FLAG)):
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print(next(rng) ^ ord(FLAG[i]))
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if __name__ == "__main__":
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main()
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