Distributed Cryptography Based on the Proofs of Work

Motivated by the recent success of Bitcoin we study the question of constructing distributed cryptographic protocols in a fully peer-to-peer scenario (without any trusted setup) under the assumption that the adversary has limited computing power. We propose a formal model for this scenario and then we construct the following protocols working in it: (i) a broadcast protocol secure under the assumption that the honest parties have computing power that is some non-negligible fraction of computing power of the adversary (this fraction can be small, in particular it can be much less than 1/2), (ii) a protocol for identifying a set of parties such that the majority of them is honest, and every honest party belongs to this set (this protocol works under the assumption that the majority of computing power is controlled by the honest parties). Our broadcast protocol can be used to generate an unpredictable beacon (that can later serve, e.g., as a genesis block for a new cryptocurrency). The protocol from Point (ii) can be used to construct arbitrary multiparty computation protocols. Our main tool for checking the computing power of the parties are the Proofs of Work (Dwork and Naor, CRYPTO 92). Our broadcast protocol is built on top of the classical protocol of Dolev and Strong (SIAM J. on Comp. 1983). Although our motivation is mostly theoretic, we believe that our ideas can lead to practical implementations (probably after some optimizations and simplifications). We discuss some possible applications of our protocols at the end of the paper

Socialism and the blockchain

Bitcoin (BTC) is often cited as Libertarian. However, the technology underpinning Bitcoin, blockchain, has properties that make it ideally suited to Socialist paradigms. Current literature supports the Libertarian viewpoint by focusing on the ability of Bitcoin to bypass central authority and provide anonymity; rarely is there an examination of blockchain technology's capacity for decentralised transparency and auditability in support of a Socialist model. This paper conducts a review of the blockchain, Libertarianism, and Socialist philosophies. It then explores Socialist models of public ownership and looks at the unique cooperative properties of blockchain that make the technology ideal for supporting Socialist societies. In summary, this paper argues that blockchain technologies are not just a Libertarian tool, they also enhance Socialist forms of governance

Ofelimos:Combinatorial optimization via proof-of-useful-work

Minimizing the energy cost and carbon footprint of the Bitcoin blockchain and related protocols is one of the most widely identified open questions in the cryptocurrency space. Substituting the proof-of-work (PoW) primitive in Nakamoto’s longest-chain protocol with a proof of useful work (PoUW) has been long theorized as an ideal solution in many respects but, to this day, the concept still lacks a convincingly secure realization. In this work we put forth Ofelimos, a novel PoUW-based blockchain protocol whose consensus mechanism simultaneously realizes a decentralized optimization-problem solver. Our protocol is built around a novel local search algorithm, which we call Doubly Parallel Local Search (DPLS), that is especially crafted to suit implementation as the PoUW component of our blockchain protocol. We provide a thorough security analysis of our protocol and additionally present metrics that reflect the usefulness of the system. DPLS can be used to implement variants of popular local search algorithms such as WalkSAT that are used for real world combinatorial optimization tasks. In this way, our work paves the way for safely using blockchain systems as generic optimization engines for a variety of hard optimization problems for which a publicly verifiable solution is desired

Cryptocurrencies and beyond: using design science research to demonstrate diverse applications of blockchains

This thesis investigates blockchain technology and whether its mutually cooperative topology and commons-based peer production practices have implications for society because, instead of the traditional top-down, centralised model of governance, blockchains represent an alternative way of collaborating. Much of the literature anticipates the vast potential of the permanent and publicly auditable nature of the propagated values of blockchains. Indeed, writers have supposed that the smart contract capabilities of the technology may prove revolutionary for areas beyond that of the economic domain targeted by the cryptocurrency Bitcoin, which is the first successful use-case of a blockchain. However, few advanced use cases beyond that economic realm have materialised; this research demonstrates such usecases. This thesis asks four research questions. The first asks whether blockchains can help reduce energy consumption. The second asks whether blockchains can help digitise the informal sector. The third asks whether blockchains can help counter fake news. The final question asks whether blockchains can help address criticisms of humanitarian aid. Those topics are four amongst many urgent problems currently facing humankind, and therefore, the overarching research question of this thesis becomes whether blockchains can help humanity. This work advances the supposed potential of blockchains proposed by current literature by using design science research to create software artefacts that propose solutions for incentivising energy efficiency, fighting financial fraud, providing digital provenance and adding trust to humanitarian aid reporting. By demonstrating blockchain-based software solutions in those four topic areas, this thesis concludes that blockchains can help humanity. However, if they are to help society address some of its problems, blockchains have significant technological and organisational barriers to overcome. Furthermore, the idea that blockchains can help humanity is a form of techno-determinism and this research concludes that it is impossible to solve every issue by diversifying technical operations; humankind must also change political, economic, and cultural goals, too. Nevertheless, this thesis has implications for regulators, despite the barriers and false solutionism offered by technology because, rather than the trusted lawmakers and experts that nations used to look up to as oracles of truth, now it may be possible to look to blockchains, instead

Ofelimos: Combinatorial Optimization via Proof-of-Useful-Work \\ A Provably Secure Blockchain Protocol

Minimizing the energy cost and carbon footprint of the Bitcoin blockchain and related protocols is one of the most widely identified open questions in the cryptocurrency space. Substituting the proof-of-work (PoW) primitive in Nakamoto\u27s longest chain protocol with a {\em proof of useful work} (PoUW) has been long theorized as an ideal solution in many respects but, to this day, the concept still lacks a convincingly secure realization. In this work we put forth Ofelimos, a novel PoUW-based block\-chain protocol whose consensus mechanism simultaneously realizes a decentralized optimization-problem solver. Our protocol is built around a novel local search algorithm, which we call Doubly Parallel Local Search (DPLS), that is especially crafted to suit implementation as the PoUW component of our blockchain protocol. We provide a thorough security analysis of our protocol and additionally present metrics that reflect the usefulness of the system. As an illustrative example we show how DPLS can implement a variant of WalkSAT and experimentally demonstrate its competitiveness with respect to a vanilla WalkSAT implementation. In this way, our work paves the way for safely using blockchain systems as generic optimization engines for a variety of hard optimization problems for which a publicly verifiable solution is desired

Exploring blockchain technologies with an innovative multi-layered ontology design tool and eMudra – a novel peer to peer currency exchange application

Recent years have witnessed significant interest in shared economy applications and consequently a proliferation of such applications have emerged where people are monetizing their things. This thesis focuses on solving the problem of leftover foreign currency exchange as a shared economy application. Existing shared economy applications such as Ola, Uber or Airbnb are not deployed as decentralized applications (Dapps) leveraging blockchain and the Internet of Things (IoT), which are relatively recent technologies leading to more efficient applications that do not require the intervention of trusted third parties. Blockchain technology can be merged with IoT infrastructure to provide an immutable ledger of all the transactions related to shared economy applications; an immutable ledger is critical to the elimination of trusted third parties, making the system trustless. When blockchain and IoT are combined they can give rise to a plethora of useful shared economy applications — automatic payment mechanisms, digital rights management are some instances and in the case of this thesis a unique solution for the leftover foreign currency exchange problem. This thesis demonstrates the implementation of a novel permissioned consortium blockchain-based leftover foreign currency exchange platform that has been designed using a multi-layered blockchain ontology created with an innovative ontology design tool. The leftover foreign currency exchange problem arises because every year millions of travellers undertake international tours and need to perform currency exchange. However, there is a deficit of suitable currency exchange applications that would help travellers exchange money profitably and conveniently, especially small amounts of cash. This thesis proposes a novel peer to peer currency exchange application – e-Mudra, exploiting blockchain technology that would allow users to choose or quote their preferred exchange rates and exchange currencies including cash money with peer travellers without any middleman deciding the rates. The research work described focuses on an in-depth study of blockchain technology and a new multi-layered blockchain ontology is created with an innovative ontology design tool that facilitates generation of simple and complex ontologies enabling the design of blockchain (and other) applications using these ontologies. The novel ontology design tool created in this research work following a new Ontology Development Life Cycle and an ontology design methodology was used to design a blockchain ontology and a wallet ontology as examples of use, where the currency exchange application design (e-Mudra) is an instance of the blockchain ontology