NTRU is a well-known lattice-based cryptosystem that can be described using polynomial rings. The public-key encryption scheme NTRUEncrypt has the advantage of having short keys with fast encryption/decryption algorithms and is considered a viable candidate for post-quantum cryptography. There is also a signature scheme called NTRUSign, though its security is less trusted compared to NTRUEncrypt.

The task of the student is to understand and summarise how the two schemes work, the attacks against them in the literature and the countermeasures proposed to resist these attacks.

[1] J. Hoffstein, J. Pipher, and J. H. Silverman, ‘NTRU: A ring-based public key cryptosystem’. doi: 10.1007/BFb0054868.

[2] J. Hoffstein, N. Howgrave-Graham, J. Pipher, J. H. Silverman, and W. Whyte, ‘NTRUSign: Digital Signatures Using the NTRU Lattice’. doi: 10.1007/3-540-36563-X_9.

[3] J. Hoffstein, N. Howgrave-Graham, J. Pipher, and W. Whyte, ‘Practical Lattice-Based Cryptography: NTRUEncrypt and NTRUSign’. doi: 10.1007/978-3-642-02295-1_11.

• Security in Communications and Storage