Solving NTRU Challenges Using the New Progressive BKZ Library

Sammanfattning: NTRU is a public-key cryptosystem, where the underlying mathematical problem is currently safe against large-scale quantum computer attacks. The system is not as well investigated, as for example RSA, and the company behind NTRU has created the NTRU Challenges, to remedy this. These challenges consist of 27 different public keys of increasing size, where the task in each challenge is to calculate (something similar to) the private key. The goal of this thesis was to examine different attacks against the NTRU Challenges and solve as many challenges as possible. By lattice reduction attacks, using a recently published new progressive BKZ algorithm, the first five challenges were solved, while the current biggest solved challenge by any researcher is challenge number seven.