rua

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本WP由Vanish提供

题目考点

• RSA

• 低指数加密攻击

解题思路

rsa低加密指数攻击，直接套先知上的一个脚本，刚开始测e=3，发现失败，于是爆破e

import binascii,gmpy2
def CRT(mi, ai):
    assert(reduce(gmpy2.gcd,mi)==1)
    assert (isinstance(mi, list) and isinstance(ai, list))
    M = reduce(lambda x, y: x * y, mi)
    ai_ti_Mi = [a * (M / m) * gmpy2.invert(M / m, m) for (m, a) in zip(mi, ai)]
    return reduce(lambda x, y: x + y, ai_ti_Mi) % M
for e in range(1,20):
    try:
        m=gmpy2.iroot(CRT([n1,n2,n3], [c1,c2,c3]), e)[0]
        print(binascii.unhexlify(hex(m)[2:].strip("L")))
    except:
        pass

Flag

flag{83f4dc02-22ee-44dd-abf2-2fe64f87512f}