Paper 2020/339

Cracking Matrix Modes of Operation with Goodness-of-Fit Statistics

George Teseleanu

Abstract

The Hill cipher is a classical poly-alphabetical cipher based on matrices. Although known plaintext attacks for the Hill cipher have been known for almost a century, feasible ciphertext only attacks have been developed only about ten years ago and for small matrix dimensions. In this paper we extend the ciphertext only attacks for the Hill cipher in two ways. First, we present two attacks for the affine version of the Hill cipher. Secondly, we show that the presented attacks can be extended to several modes of operations. We also provide the reader with several experimental results and show how the message's language can influence the presented attacks.