A Simple and Efficient Key Reuse Attack on NTRU Cryptosystem

Abstract

In 1998, Jeffrey Hoffstein, Jill Pipher, and Joseph H. Silverman introduced the famous NTRU cryptosystem, and called it A ring-based public key cryptosystem . Actually, it turns out to be a lattice based cryptosystem that is resistant to Shor\u27s algorithm. There are several modifications to the original NTRU and two of them are selected as round 2 candidates of NIST post quantum public key scheme standardization. In this paper, we present a simple attack on the original NTRU scheme. The idea comes from Ding et al.\u27s key mismatch attack. Essentially, an adversary can find information on the private key of a KEM by not encrypting a message as intended but in a manner which will cause a failure in decryption if the private key is in a certain form. In the present, NTRU has the encrypter generating a random polynomial with small coefficients, but we will have the coefficients be large . After this, some further work will create an equivalent key