An example of a cryptographic hash function based on a modified sponge scheme

Abstract

Currently, the «Sponge» scheme is the most successful and promising way to build modern cryptographic hash functions. The purpose of this article is to build an example of a cryptographic hash function based on this scheme. The main and important component of the scheme is the internal function, which is a fixed-length transformation or permutation that operates with a fixed number of bits that make up the internal state of the function. The classic «Sponge» scheme and most of its modifications assume only one internal function. In this paper, we consider a modification of this scheme, which involves the use of a set of internal functions. Three new variants of the internal function are considered. First, we consider a variant of the internal function based on the use of word ring feedback with carry shift registers. Second, we consider a new version of the internal function based on the Keccak permutation. Third, we consider an internal function constructed using the generalized AES design methodology. Then, based on the modified scheme and using these three internal functions, a hash algorithm is constructed. The selection of one of these three internal functions as part of the entire scheme is determined using message dependent selection bits generated in a pseudo-random manner.