Impact of Rotations in the Salsa20/8 Image Encryption Scheme

Abstract

Salsa20 uses a single set of rotation distances within its core function. To our knowledge, no design rationales on the choice of rotation distances are given on the Salsa20 core function. This is the first paper that analyzes rotations influence over the output sequence in the Salsa20 image encryption scheme. We focus on the Salsa20/8 image encryption scheme and use recent developments in the analysis of the Salsa20 core function to evaluate the security implications of using different sets of rotation distances in the core function. Finally, we give some observations on the some sets of rotation distances used in the Salsa20/8 image encryption scheme.