The dynamics of the CBC Mode of Operation

TL;DR

This paper investigates the complex dynamical properties of the CBC mode of operation in cryptography, analyzing its chaotic behavior, topological mixing, and entropy to deepen understanding of its security features.

Contribution

It provides a comprehensive topological analysis of CBC mode, including mixing properties and entropy, extending previous chaos-based studies.

Findings

CBC exhibits chaotic behavior under certain conditions

The mode demonstrates topological mixing properties

Topological entropy of CBC is quantitatively evaluated

Abstract

In cryptography, the Cipher Block Chaining (CBC), one of the most commonly used mode in recent years, is a mode of operation that uses a block cipher to provide confidentiality or authenticity. In our previous research work, we have shown that this mode of operation exhibits, under some conditions, a chaotic behaviour. We have studied this behaviour by evaluating both its level of sensibility and expansivity. In this paper, we intend to deepen the topological study of the CBC mode of operation and evaluate its property of topological mixing. Additionally, other quantitative evaluations are performed, and the level of topological entropy has been evaluated too.