PoTS - A Secure Proof of TEE-Stake for Permissionless Blockchains

Proof-of-Stake (PoS) protocols have been actively researched for the past few years. PoS finds direct applicability in permissionless blockchain platforms and emerges as one of the strongest candidates to replace the largely inefficient Proof of Work mechanism that is currently plugged in the majority of existing permissionless blockchain systems. Although a number of PoS variants have been proposed, these protocols suffer from a number of security shortcomings. Namely, most existing PoS variants are either subject to the nothing at stake, the long range, or the stake grinding attacks which considerably degrade security in the blockchain. These shortcomings do not result from a lack of foresight when designing these protocols, but are inherently due to the ease of manipulating stake when compared to other more established variants, such as work . In this paper, we address these problems and propose a secure Proof of Stake protocol, PoTS, that leverages Trusted Execution Environments (TEEs), such as Intel SGX, to ensure that each miner can generate at most one block per height for strictly increasing heights—thus thwarting the problem of nothing at stake and a large class of long-range attacks. In combination with TEEs, PoTS additionally uses cryptographic techniques to also prevent grinding attacks and protect against posterior corruption. We show that our protocol is secure, in the sense of well-established cryptographic notions for blockchain protocols, down to realistic hardware assumptions on TEE and well-established cryptographic assumptions. Finally, we evaluate the performance of our proposal by means of implementation. Our evaluation results show that PoTS offers a strong tradeoff between security of performance of the underlying PoS protocol

Decentralised computer systems

The architecture of the Web was designed to enable decentralised exchange of information. Early architects envisioned an egalitarian yet organic society thriving in cyberspace. The reality of the Web today, unfortunately, does not bear out these visions: information networks have repeatedly shown a tendency towards consolidation and centralisation with the current Web split between a handful of large corporations. The advent of Bitcoin and successor blockchain networks re-ignited interest in developing alternatives to the centralised Web and paving a way back to the earlier architectural visions for the Web. This has led to immense hype around these technologies with the cryptocurrency market valued at several hundred billions of dollars at the time of writing. With great hype, apparently, come great scams. I start off by analysing the use of Bitcoin as an enabler for crime and then present both technical solutions as well as policy recommendations to mitigate the harm these crimes cause. These policy recommendations then lead us on to look more closely at cryptocurrency's tamer cousin: permissioned blockchains. These systems, while less revolutionary in their premise, nevertheless aim to provide sweeping improvements in the efficiency and transparency of existing enterprise systems. To see whether they work in practice, I present the results of my work in delivering a production permissioned blockchain system to real users. This involves comparing several permissioned blockchain systems, exploring their deficiencies and developing solutions for the most egregious of those. Lastly, I do a deep dive into one of the most persistent technical issues with permissioned blockchains, and decentralised networks in general: the lack of scalability in their consensus mechanisms. I present two novel consensus algorithms that aim to improve upon the state of the art in several ways. The first is designed to enable existing permissioned blockchain networks to scale to thousands of nodes. The second presents an entirely new way of building decentralised consensus systems utilising a trie-based data structure at its core as opposed to the usual linear ledgers used in current systems

Disrupting Finance

This open access Pivot demonstrates how a variety of technologies act as innovation catalysts within the banking and financial services sector. Traditional banks and financial services are under increasing competition from global IT companies such as Google, Apple, Amazon and PayPal whilst facing pressure from investors to reduce costs, increase agility and improve customer retention. Technologies such as blockchain, cloud computing, mobile technologies, big data analytics and social media therefore have perhaps more potential in this industry and area of business than any other. This book defines a fintech ecosystem for the 21st century, providing a state-of-the art review of current literature, suggesting avenues for new research and offering perspectives from business, technology and industry

Disrupting Finance : FinTech and Strategy in the 21st Century

This open access Pivot demonstrates how a variety of technologies act as innovation catalysts within the banking and financial services sector. Traditional banks and financial services are under increasing competition from global IT companies such as Google, Apple, Amazon and PayPal whilst facing pressure from investors to reduce costs, increase agility and improve customer retention. Technologies such as blockchain, cloud computing, mobile technologies, big data analytics and social media therefore have perhaps more potential in this industry and area of business than any other. This book defines a fintech ecosystem for the 21st century, providing a state-of-the art review of current literature, suggesting avenues for new research and offering perspectives from business, technology and industry