A Flexible Framework for Exploring, Evaluating, and Comparing SHA-2 Designs

Abstract

Hash functions are a crucial tool in a large variety of applications, ranging from security protocols to cryptocurrencies down to the Internet-of-Things devices used, for example, as biomedical appliances. In particular, SHA-2 is today a ubiquitous hashing primitive. Its acceleration has driven a wealth of contributions in the technical literature and even a whole industry segment involving dedicated hash processing accelerators. Because of the variety of requirements in terms of performance, resources, and energy consumption as well as the impact of the particular hardware technology of choice, evaluating and comparing different architectural schemes is a nontrivial task, along with the exploration of new solutions matching given user requirements. Based on a careful review of the state of the art, this paper introduces an SHA-2 workbench to be used as a framework for evaluating different implementation styles and architectural choices. The workbench comes in the form of a generic HDL description, where the various implementation options are exposed in the form of user-configurable parameters and can be variously combined obtaining either known solutions or possibly new configurations to be explored. We systematically use the workbench to analyze the available SHA-2 architectural techniques. This extensive evaluation provides a deep understanding of the performance and energy implications of each implementation style and even allows the identification of nonobvious matches between architectural choices and target technologies in order to optimize hash rate and area efficiency figures.

Keywords

• Accelerators
• hash functions
• SHA-2