Chapter

Applied Cryptography and Network Security

Volume 4521 of the series Lecture Notes in Computer Science pp 432-442

Sliding Window Method for NTRU

  • Mun-Kyu LeeAffiliated withSchool of Computer Science and Engineering, Inha University, Incheon 402-751
  • , Jung Woo KimAffiliated withSchool of Computer Science and Engineering, Seoul National University, Seoul 151-742
  • , Jeong Eun SongAffiliated withSchool of Computer Science and Engineering, Inha University, Incheon 402-751
  • , Kunsoo ParkAffiliated withSchool of Computer Science and Engineering, Seoul National University, Seoul 151-742

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Abstract

The NTRU cryptosystem is a ring-based public key system using hard problems over lattices. There has been an extensive research on efficient implementation of NTRU operations, including recent results such as Bailey et al.’s software implementation over a resource-constrained device and Gaubatz et al.’s hardware implementation using only 3,000 gates. In this paper, we present a new algorithm to improve further the performance of NTRU. We speed up the encryption and decryption operations of NTRU up to 32% using some temporary memory, and if we can use precomputation, then the speed-up becomes up to 37%. Our method is based on the observation that specific sub-operations are repeated frequently in the underlying polynomial operations of NTRU.