Development of modification of the post-quantum public-key cryptosystem NTRUENCRYPT

This work is devoted to the development of a modification of the post-quantum public-key cryptosystem NTRUEncrypt. Given that two main requirements for modern cryptographic algorithms are resistance to attacks (including quantum attacks) and performance, the developed modification offers an improvement in both aspects. Karatsuba algorithm for fast polynomial multiplication is employed to achieve better performance. The modification also includes additional protection against a chosen ciphertext attack that can be effectively against standard NTRUEncrypt. Performance test of the developed modification confirmed that less time is required for key generation, encryption and decryption in comparison with the classical algorithm. The modified algorithm is then applied to implement an asymmetric encryption system with a graphical user interface that allows establishing communication between two users with resistance to both classical and quantum attacks.