Protocol indepedence through disjoint encryption under Exclusive-OR

TL;DR

This paper demonstrates that protocol independence can be achieved with disjoint encryption even when using operators like Exclusive-OR that induce complex equational theories, addressing multi-protocol attack vulnerabilities.

Contribution

It extends prior work by proving protocol independence under disjoint encryption for operators like Exclusive-OR, which break the free algebra assumption.

Findings

Disjoint encryption prevents multi-protocol attacks with Exclusive-OR.

Protocol independence is achievable under equational theories.

The approach applies to commonly used cryptographic operators.

Abstract

Multi-protocol attacks due to protocol interaction has been a notorious problem for security. Gutman-Thayer proved that they can be prevented by ensuring that encrypted messages are distinguishable across protocols, under a free algebra. In this paper, we prove that a similar suggestion prevents these attacks under commonly used operators such as Exclusive-OR, that induce equational theories, breaking the free algebra assumption.