Paper 2017/849

FAST: A New Family of Secure and Efficient Tweakable Enciphering Schemes

Debrup Chakraborty and Sebati Ghosh and Cuauhtemoc Mancillas Lopez and Palash Sarkar

Abstract

This work describes a new family of cryptographic constructions called FAST. Several instantiations of FAST are described. These are targeted towards two goals, the specific task of disk encryption on one hand and a more general scheme suitable for a wide variety of applications on the other. Formally, FAST is a new family of tweakable enciphering schemes. It is built as a mode of operation of a fixed input length pseudo-random function and an appropriate hash function. FAST uses a single-block key, is parallelisable and can be instantiated using only the encryption function of an appropriate block cipher. The hash function can be instantiated using either the Horner's rule based usual polynomial hashing or the more efficient Bernstein-Rabin-Winograd polynomials. Security is rigorously analysed using the standard provable security approach and concrete security bounds are derived. Detailed and careful implementations of FAST in both software and hardware are presented. The results from the implementations show that FAST compares favourably to all previous schemes. Based on these results, we put forward FAST as a serious candidate for standardisation and deployment.