64 research outputs found
Applications of the Blockchain using cryptography
Get PDFPhD ThesisWe have witnessed the rise of cryptocurrencies in the past eight years. Bitcoin and Ethereum
are the world’s most successful cryptocurrencies with market capitalisations of 21bn respectively in June 2017. The innovation behind these cryptocurrencies is the
blockchain which is an immutable and censorship resistant public ledger. Bitcoin introduced
the blockchain to trade a single asset (i.e. bitcoins), whereas Ethereum adopted the
blockchain to store and execute expressive smart contracts. In this thesis, we consider cryptographic
protocols that bootstrap trust from the blockchain. This includes secure end-to-end
communication between two pseudonymous users, payment protocols, payment networks
and decentralised internet voting. The first three applications rely on Bitcoin, whereas the
final e-voting application is realised using Ethereum.
First, it is important to highlight that Bitcoin was designed to protect the anonymity (or
pseudonymity) for financial transactions. Nakamoto proposed that financial privacy is achievable
by storing each party’s pseudonym (and not their real-world identity) in a transaction.
We highlight that this approach for privacy has led to real-world authentication issues as
merchants are failing to re-authenticate customers in post-transaction correspondence. To
alleviate these issues, we propose an end-to-end secure communication protocol for Bitcoin
users that does not require any trusted third party or public-key infrastructure. Instead, our
protocol leverages the Blockchain as an additional layer of authentication. Furthermore,
this insight led to the discovery of two attacks in BIP70: Payment Protocol which is a
community-accepted standard used by more than 100,000 merchants. Our attacks were
acknowledged by the leading payment processors including Coinbase, BitPay and Bitt. As
well, we have proposed a revised Payment Protocol that prevents both attacks.
Second, Bitcoin as deployed today does not scale. Scalability research has focused on two
directions: 1) redesigning the Blockchain protocol, and 2) facilitating ‘off-chain transactions’
and only consulting the Blockchain if an adjudicator is required. We focus on the latter
and provide an overview of Bitcoin payment networks. These consist of two components:
payment channels to facilitate off-chain transactions between two parties, and the capability
to fairly exchange bitcoins across multiple channels. We compare Duplex Micropayment
Channels and Lightning Channels, before discussing Hashed Time Locked Contracts which
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enable Bitcoin-based payment networks. Furthermore, we highlight challenges in routing
and path-finding that need to be overcome before payment networks are practically feasible.
Finally, we study the feasibility of executing cryptographic protocols on Ethereum. We
provide the first implementation of a decentralised and self-tallying internet voting protocol
with maximum voter privacy as a smart contract. The Open Vote Network is suitable for
boardroom elections and is written as a smart contract for Ethereum. Unlike previously
proposed Blockchain e-voting protocols, this is the first implementation that does not rely on
any trusted authority to compute the tally or to protect the voter’s privacy. Instead, the Open
Vote Network is a self-tallying protocol, and each voter is in control of the privacy of their
own vote such that it can only be breached by a full collusion involving all other voters. The
execution of the protocol is enforced using the consensus mechanism that also secures the
Ethereum blockchain. We tested the implementation on Ethereum’s official test network to
demonstrate its feasibility. Also, we provide a financial and computational breakdown of its
execution cost
Formal Modelling and Security Analysis of Bitcoin\u27s Payment Protocol
Get PDFThe Payment Protocol standard BIP70, specifying how payments in Bitcoin are performed by merchants and customers, is supported by the largest payment processors and most widely-used wallets. The protocol has been shown to be vulnerable to refund attacks due to lack of authentication of the refund addresses. In this paper, we give the first formal model of the protocol and formalise the refund address security goals for the protocol, namely refund address authentication and secrecy. The formal model utilises communication channels as abstractions conveying security goals on which the protocol modeller and verifier can rely. We analyse the Payment Protocol confirming that it is vulnerable to an attack violating the refund address authentication security goal. Moreover, we present a concrete protocol revision proposal supporting the merchant with publicly verifiable evidence that can mitigate the attack. We verify that the revised protocol meets the security goals defined for the refund address. Hence, we demonstrate that the revised protocol is secure, not only against the existing attacks, but also against any further attacks violating the formalised security goals.30 pages, 6 figures. This is an accepted manuscript to appear in Computers & Security. Please cite as: Modesti, Shahandashti, McCorry, and Hao. Formal Modelling and Security Analysis of Bitcoin\u27s Payment Protocol . To appear in Computer & Security, Elsevier, 202
The Creation of an E-Tutorial to Support Learning Embryology
No full textEmbryology is a complex subject that many students struggle to understand. With the
advances of digital technologies, we sought to create a fully interactive e- learning resource
to facilitate learning in this complex field. Therefore, the aim of this project was to create a
digital resource which was created by a student, for students.
We based this e-tutorial on the embryology curriculum from the Level 3 Honours BSc degree
at the University of Glasgow. We ensured all aims and objectives were incorporated into the
tutorial. By using Articulate 360, we created an e-tutorial which enabled the user to explore
weeks 1 – 4 of development. Novel images and cartoons were created by the author and
incorporated into the tutorial. This meant that there were no copyright issues from using
materials from other sources. Images were designed and created using Paint Tool Sai.
A simple interactive format was created with text related to each week of development.
This linked to the intended learning outcomes, but ensured a unique presentation of
resources to enhance learning. There was a fully interactive quiz at the end of each of the
weeks, including hints and tips, with links back to the relevant part of the tutorial.
This e-tutorial has now been adopted into the local curriculum and has been requested by
several Scottish universities and the north of England to embed into their curricula. This
study has shown how a co-creation of educational resources can result in the production of
a novel and interactive learning resource
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