Hardware Implementation of the NTRU Deterministic Public Key Encryption

Abstract

The increasing advancements in quantum computing have led to an increasing danger for the cyberspace. The current cryptographic algorithms that are used to enable secure communication across insecure channels have the potential to be brute-forced by sufficiently powerful quantum computers, endangering the security of many electronic devices and protocols that use popular algorithms such as RSA. Although it is not feasible currently, these advancements in quantum computing are accelerating rapidly and the impact this could have on the security of the cyberspace is too great, therefore countermeasures must be considered. To protect against this threat, the National Institute of Standards and Technology (NIST) has started an initiative to work towards standardizing quantum-resistant cryptoschemes before the advancements in quantum computing reach such a level. This has led to a great amount of collaboration by researchers to develop and analyze the security of these quantum-proof schemes over the past six years.

This thesis explores the various post-quantum cryptoschemes that are currently being considered, outlining their differences and the potential advantage of using each scheme. While all of the current submissions are required to have a software implementation to be part of the submission, this is not the case for a hardware implementation. Hardware implementations can have different vulnerabilities than software implementations and, due to this, having one or preferably multiple hardware implementations available for these schemes would greatly advance the security analysis that can be performed for these candidates. Therefore, this thesis describes the hardware implementation process of one such scheme, NTRU, one of the longest standing lattice-based schemes, since this danger of quantum computing is equally dangerous for the many hardware devices and chips that are used worldwide. It discusses the various design decisions that have been made during the implementation and presents all functions that have been implemented to perform the encryption and decryption step of the deterministic public key encryption (DPKE) algorithm of NTRU. This implementation combines work that has been done for the previous NTRU submissions and adds additional logic to support the new and adjusted parts of the current NTRU algorithm. The results show a fully functional encryption and decryption functionality of the NTRU cryptoscheme where the full encryption function can be performed in 3038 clock cycles while still maintaining a considerably low area usage, showing a speedup of 16 when compared to an optimized software implementation. Aside from this result, this thesis also provides several potential adjustments to the hardware implementation that can be made to reduce the decryption time at the cost of additional area so that the hardware can be tuned depending on the desired specifications.