Tithonus: A Bitcoin Based Censorship Resilient System

TL;DR

Tithonus leverages Bitcoin's peer-to-peer gossip protocol to enable fast, cost-effective, and censorship-resistant communication, significantly improving upon previous blockchain-based solutions in efficiency and unobservability.

Contribution

It introduces a novel framework that exploits Bitcoin's gossip protocol for censorship-resistant communication, reducing costs and increasing throughput compared to prior methods.

Findings

Reduces data transfer costs by 100x compared to state-of-the-art solutions.

Increases goodput by 3000% to 5000%.

Client transactions are hard to detect, server transactions resist censorship.

Abstract

Providing reliable and surreptitious communications is difficult in the presence of adaptive and resourceful state level censors. In this paper we introduce Tithonus, a framework that builds on the Bitcoin blockchain and network to provide censorship-resistant communication mechanisms. In contrast to previous approaches, we do not rely solely on the slow and expensive blockchain consensus mechanism but instead fully exploit Bitcoin's peer-to-peer gossip protocol. We develop adaptive, fast and cost effective data communication solutions that camouflage client requests into inconspicuous Bitcoin transactions. We propose solutions to securely request and transfer content, with unobservability and censorship resistance, and free, pay-per-access and subscription based payment options. When compared to state-of-the-art Bitcoin writing solutions, Tithonus reduces the cost of transferring data to censored clients by 2 orders of magnitude and increases the goodput by 3 to 5 orders of magnitude. We show that Tithonus client initiated transactions are hard to detect, while server initiated transactions cannot be censored without creating split world problems to the Bitcoin blockchain.