A measurement study of peer-to-peer bootstrapping and implementations of delay-based cryptography

This thesis researches two distinct areas of study in both peer-to-peer networking for
modern cryptocurrencies and implementations of delay-based cryptography.
The first part of the thesis researches elements of peer-to-peer network mechanisms,
with a specific focus on the dependencies on centralised infrastructure required for the
initial participation in such networks.
Cryptocurrencies rely on decentralised peer-to-peer networks, yet the method by
which new peers initially join these networks, known as bootstrapping, presents a significant
challenge. Our original research consists of a measurement study of 74 cryptocurrencies.
Our study reveals a prevalent reliance on centralised infrastructure which leads
to censorship-prone bootstrapping techniques leaving networks vulnerable to censorship
and manipulation.
In response, we explore alternative bootstrapping methods seeking solutions less
susceptible to censorship. However, our research demonstrates operational challenges
and limitations which hinder their effectiveness, highlighting the complexity of achieving
censorship-resistance in practice.
Furthermore, our global measurement study uncovers the details of cryptocurrency
peer-to-peer networks, revealing instances outages and intentional protocol manipulation
impacting bootstrapping operations. Through a volunteer network of probes deployed
across 42 countries, we analyse network topology, exposing centralisation tendencies and
unintentional peer exposure.
Our research also highlights the pervasive inheritance of legacy bootstrapping methods,
perpetuating security vulnerabilities and censorship risks within cryptocurrency
systems. These findings illuminate broader concerns surrounding decentralisation and
censorship-resistance in distributed systems.
In conclusion, our study offers valuable insights into cryptocurrency bootstrapping
techniques and their susceptibility to censorship, paving the way for future research and
interventions to enhance the resilience and autonomy of peer-to-peer networks.
In the second part of the thesis, attention shifts towards delay-based cryptography,
where the focus lies on the creation and practical implementations of timed-release encryption
schemes. Drawing from the historical delay-based cryptographic protocols, this
thesis presents two original research contributions.
The first is the creation of a new timed-release encryption scheme with a property
termed implicit authentication. The second contribution is the development of a practical
construction called TIDE (TIme Delayed Encryption) tailored for use in sealed-bid
auctions.
Timed-Release Encryption with Implicit Authentication (TRE-IA) is a cryptographic
primitive which presents a new property named implicit authentication (IA). This property
ensures that only authorised parties, such as whistleblowers, can generate meaningful
ciphertexts. By incorporating IA techniques into the encryption process, TRE-IA
augments a new feature in standard timed-release encryption schemes by ensuring that
only the party with the encryption key can create meaningful ciphertexts. This property
ensures the authenticity of the party behind the sensitive data disclosure. Specifically, IA
enables the encryption process to authenticate the identity of the whistleblower through
the ciphertext. This property prevents malicious parties from generating ciphertexts
that do not originate from legitimate sources. This ensures the integrity and authenticity
of the encrypted data, safeguarding against potential leaks of information not vetted
by the party performing the encryption.
TIDE introduces a new method for timed-release encryption in the context of sealedbid
auctions by creatively using classic number-theoretic techniques. By integrating
RSA-OEAP public-key encryption and the Rivest Shamir Wagner time-lock assumption
with classic number theory principles, TIDE offers a solution that is both conceptually
straightforward and efficient to implement.
Our contributions in TIDE address the complexities and performance challenges
inherent in current instantiations of timed-release encryption schemes. Our research
output creates a practical timed-release encryption implementation on consumer-grade
hardware which can facilitate real-world applications such as sealed-bid auctions with
clear steps for implementation.
Finally, our thesis concludes with a review of the prospects of delay-based cryptography
where we consider potential applications such as leveraging TIDE for a public
randomness beacon.