Paper 2019/824

Hardware Implementations of NIST Lightweight Cryptographic Candidates: A First Look

Behnaz Rezvani and William Diehl

Abstract

Security in the Internet of Things (IoT) is challenging. The need for lightweight yet robust cryptographic solutions suitable for the IoT calls for improved design and implementation of constructs such as Authenticated Encryption with Associated Data (AEAD) which can ensure confidentiality, integrity and authenticity of data in one algorithm. The U.S. National Institute of Standards and Technology (NIST) has embarked on a multi-year effort called the Lightweight Cryptography (LWC) Standardization Process to evaluate lightweight AEAD and optional hash algorithms for inclusion in U.S. federal standards. As candidates are evaluated for many characteristics including hardware resources and performance, obtaining results of hardware implementations as early as possible, i.e., even in round 1, is preferable. In this research, we implement three NIST LWC round 1 candidate ciphers, SpoC, Spook, and GIFT-COFB, in the Artix-7 FPGA. Implementations are compliant with the previously-validated CAESAR Hardware Applications Programming Interface (API) for Authenticated Ciphers, and are tested in actual hardware. Implementations show that GIFT-COFB has the highest Throughput-to-Area (TPA) ratio, by a 4.4 factor margin over Spook. Additionally, the results illustrate hardware implementation challenges associated with integrating multiple cryptographic primitives into one design, as well as complexities due to padding and truncation.