使用格中的最短向量对未知向量进行逼近的方法,证明了在已知乘子a和模数p的条件下,若连续的wi满足|ui-wi|是一个很小的数时,在多项式时间内可以恢复出逆同余发生器的移位B. 本文的结论表明将逆同余发生器直接应用于密码学必须十分慎重.
In this paper, we prove that given the multiplier a, modular p and sufficiently many of the most significant bits of three consecutive outputs of the inversive generator, one can disclose the shift b and the initial value if those outputs do not lie in a small set, by the method of using the shortest vector in the lattice to approximate the unknown vector. The result of this paper shows that we should be careful when we use the inversive generator in a cryptosystem.