Defending Hash Tables from Subterfuge with Depth Charge

TL;DR

This paper introduces Depth Charge, a resource burning defense mechanism for hash tables that mitigates Byzantine attacks by charging costs based on object depth, reducing attacker impact.

Contribution

The paper proposes Depth Charge, a novel RB-based algorithm that dynamically sets costs to defend hash tables against malicious attacks.

Findings

Depth Charge effectively reduces attacker's impact on hash table performance.

The algorithm's cost asymptotically remains lower than the attacker's cost under significant attack.

Demonstrates robustness of hash tables using RB in adversarial environments.

Abstract

We consider the problem of defending a hash table against a Byzantine attacker that is trying to degrade the performance of query, insertion and deletion operations. Our defense makes use of resource burning (RB) -- the the verifiable expenditure of network resources -- where the issuer of a request incurs some RB cost. Our algorithm, Depth Charge, charges RB costs for operations based on the depth of the appropriate object in the list that the object hashes to in the table. By appropriately setting the RB costs, our algorithm mitigates the impact of an attacker on the hash table's performance. In particular, in the presence of a significant attack, our algorithm incurs a cost which is asymptotically less that the attacker's cost.