CompChall: Addressing Password Guessing Attacks

TL;DR

This paper introduces CompChall, a hash-based authentication protocol that effectively counters online dictionary attacks by making login attempts computationally expensive for attackers while remaining user-friendly.

Contribution

The paper proposes a novel stateless challenge-response protocol using hash functions to prevent online dictionary attacks without increasing user difficulty.

Findings

Effective mitigation of online dictionary attacks.

Protocol remains stateless and resistant to DoS attacks.

Uses only hash functions for simplicity and security.

Abstract

Even though passwords are the most convenient means of authentication, they bring along themselves the threat of dictionary attacks. Dictionary attacks may be of two kinds: online and offline. While offline dictionary attacks are possible only if the adversary is able to collect data for a successful protocol execution by eavesdropping on the communication channel and can be successfully countered using public key cryptography, online dictionary attacks can be performed by anyone and there is no satisfactory solution to counter them. This paper presents a new authentication protocol which is called CompChall (computational challenge). The proposed protocol uses only one way hash functions as the building blocks and attempts to eliminate online dictionary attacks by implementing a challenge-response system. This challenge-response system is designed in a fashion that it does not pose any difficulty to a genuine user but is time consuming and computationally intensive for an adversary trying to launch a large number of login requests per unit time as in the case of an online dictionary attack. The protocol is stateless and thus less vulnerable to DoS (Denial of Service) attacks.