NTRUEncrypt and Lattice Attacks

NTRUEncrypt is a relatively new cryptosystem, introduced in 1996. The best known attacks on the cryptosystem are due to lattice basis reduction. In this Master’s project we have implemented lattice attacks using dimension-reduced and zero-forced lattices. Furthermore, we have reduced a modified version of the zero-forced lattice. This “non-lossy” zero-forced lattice performed better than the original zero-forced lattice, which discards information of the private key. We have also made investigations to see whether the estimated breaking times, estimations made by NTRU Cryptosystems, are reasonable or not. The tests indicate that the security estimation for the Moderate security level, using polynomials of degree 167, might be reasonable. However, the results show that the estimated breaking time for the Standard security level, where the degree of the polynomials is 263, might be a bit too optimistic. NTRUEncrypt och gitterattacker