A Simple Attack on Some Clock-Controlled Generators

TL;DR

This paper introduces a graph-theoretic method to improve edit distance attacks on clock-controlled generators, making the process more deterministic and efficient by focusing on promising search branches and pre-avoiding inconsistent states.

Contribution

It presents a novel graph-based approach that simplifies attack search trees and enhances attack determinism on specific cryptographic generators.

Findings

Deterministic attack results achieved

Pre-identified inconsistent states avoided

Improved efficiency in attack search process

Abstract

We present a new approach to edit distance attacks on certain clock-controlled generators, which applies basic concepts of Graph Theory to simplify the search trees of the original attacks in such a way that only the most promising branches are analyzed. In particular, the proposed improvement is based on cut sets defined on some graphs so that certain shortest paths provide the edit distances. The strongest aspects of the proposal are that the obtained results from the attack are absolutely deterministic, and that many inconsistent initial states of the target registers are recognized beforehand and avoided during search.