NTRU is one of the most widely used public-key cryptosystems and its security has been an active research topic.This paper proposes a new way to find NTRU-2005 private key.The algorithm is based on meet-in-the-middle attack and a quantum algorithm for searching the fixed weight target.Compared with the current classical and quantum meet-in-the-middle attacks,our algorithm has lower time and space complexity.Moreover,this attack can also be applied against different versions of NTRU.The result can help to understand the security of NTRU better.
In order to improve the attack efficiency of the New FORK-256 function, an algorithm based on Grover's quantum search algorithm and birthday attack is proposed. In this algorithm, finding a collision for arbitrary hash function only needs O(2m/3) expected evaluations, where m is the size of hash space value. It is proved that the algorithm can obviously improve the attack efficiency for only needing O(2 74.7) expected evaluations, and this is more efficient than any known classical algorithm, and the consumed space of the algorithm equals the evaluation.
