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