29 lines
667 B
Python
29 lines
667 B
Python
import os
|
|
|
|
BITS = 56
|
|
|
|
FLAG = os.getenv("FLAG", "CSCG{sH4r1nG_1nt3rn4l_sT4te_1s_d3adLy}")
|
|
|
|
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)):
|
|
num = next(rng)
|
|
print(num ^ ord(FLAG[i]))
|
|
|
|
if __name__ == "__main__":
|
|
main()
|