Energy-efficient and cost-effective reliability design in memory systems

Reliability of memory systems is increasingly a concern as memory density increases, the cell dimension shrinks and new memory technologies move close to commercial use. Meanwhile, memory power efficiency has become another first-order consideration in memory system design. Conventional reliability scheme uses ECC (Error Correcting Code) and EDC (Error Detecting Code) to support error correction and detection in memory systems, putting a rigid constraint on memory organizations and incurring a significant overhead regarding the power efficiency and area cost. This dissertation studies energy-efficient and cost-effective reliability design on both cache and main memory systems. It first explores the generic approach called embedded ECC in main memory systems to provide a low-cost and efficient reliability design. A scheme called E3CC (Enhanced Embedded ECC) is proposed for sub-ranked low-power memories to alleviate the concern on reliability. In the design, it proposes a novel BCRM (Biased Chinese Remainder Mapping) to resolve the address mapping issue in page-interleaving scheme. The proposed BCRM scheme provides an opportunity for building flexible reliability system, which favors the consumer-level computers to save power consumption. Within the proposed E3CC scheme, we further explore address mapping schemes at DRAM device level to provide SEP (Selective Error Protection). We explore a group of address mapping schemes at DRAM device level to map memory requests to their designated regions. All the proposed address mapping schemes are based on modulo operation. They will be proven, in this thesis, to be efficient, flexible and promising to various scenarios to favor system requirements. Additionally, we propose Free ECC reliability design for compressed cache schemes. It utilizes the unused fragments in compressed cache to store ECC. Such a design not only reduces the chip overhead but also improves cache utilization and power efficiency. In the design, we propose an efficient convergent cache allocation scheme to organize the compressed data blocks more effectively than existing schemes. This new design makes compressed cache an increasingly viable choice for processors with requirements of high reliability. Furthermore, we propose a novel, system-level scheme of memory error detection based on memory integrity check, called MemGuard, to detect memory errors. It uses memory log hashes to ensure, by strong probability, that memory read log and write log match with each other. It is much stronger than conventional protection in error detection and incurs little hardware cost, no storage overhead and little power overhead. It puts no constraints on memory organization and no major complication to processor design and operating system design. In the thesis, we prove that the MemGuard reliability design is simple, robust and efficient

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 formodern 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 theinitial participation in such networks.Cryptocurrencies rely on decentralised peer-to-peer networks, yet the method bywhich new peers initially join these networks, known as bootstrapping, presents a significantchallenge. Our original research consists of a measurement study of 74 cryptocurrencies.Our study reveals a prevalent reliance on centralised infrastructure which leadsto censorship-prone bootstrapping techniques leaving networks vulnerable to censorshipand manipulation.In response, we explore alternative bootstrapping methods seeking solutions lesssusceptible to censorship. However, our research demonstrates operational challengesand limitations which hinder their effectiveness, highlighting the complexity of achievingcensorship-resistance in practice.Furthermore, our global measurement study uncovers the details of cryptocurrencypeer-to-peer networks, revealing instances outages and intentional protocol manipulationimpacting bootstrapping operations. Through a volunteer network of probes deployedacross 42 countries, we analyse network topology, exposing centralisation tendencies andunintentional peer exposure.Our research also highlights the pervasive inheritance of legacy bootstrapping methods,perpetuating security vulnerabilities and censorship risks within cryptocurrencysystems. These findings illuminate broader concerns surrounding decentralisation andcensorship-resistance in distributed systems.In conclusion, our study offers valuable insights into cryptocurrency bootstrappingtechniques and their susceptibility to censorship, paving the way for future research andinterventions 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 encryptionschemes. Drawing from the historical delay-based cryptographic protocols, thisthesis presents two original research contributions.The first is the creation of a new timed-release encryption scheme with a propertytermed implicit authentication. The second contribution is the development of a practicalconstruction called TIDE (TIme Delayed Encryption) tailored for use in sealed-bidauctions.Timed-Release Encryption with Implicit Authentication (TRE-IA) is a cryptographicprimitive which presents a new property named implicit authentication (IA). This propertyensures that only authorised parties, such as whistleblowers, can generate meaningfulciphertexts. By incorporating IA techniques into the encryption process, TRE-IAaugments a new feature in standard timed-release encryption schemes by ensuring thatonly the party with the encryption key can create meaningful ciphertexts. This propertyensures the authenticity of the party behind the sensitive data disclosure. Specifically, IAenables the encryption process to authenticate the identity of the whistleblower throughthe ciphertext. This property prevents malicious parties from generating ciphertextsthat do not originate from legitimate sources. This ensures the integrity and authenticityof the encrypted data, safeguarding against potential leaks of information not vettedby the party performing the encryption.TIDE introduces a new method for timed-release encryption in the context of sealedbidauctions by creatively using classic number-theoretic techniques. By integratingRSA-OEAP public-key encryption and the Rivest Shamir Wagner time-lock assumptionwith classic number theory principles, TIDE offers a solution that is both conceptuallystraightforward and efficient to implement.Our contributions in TIDE address the complexities and performance challengesinherent in current instantiations of timed-release encryption schemes. Our researchoutput creates a practical timed-release encryption implementation on consumer-gradehardware which can facilitate real-world applications such as sealed-bid auctions withclear steps for implementation.Finally, our thesis concludes with a review of the prospects of delay-based cryptographywhere we consider potential applications such as leveraging TIDE for a publicrandomness beacon.<br/

Fractional Reserve Banking as Economic Parasitism: A Scientific, Mathematical & Historical Expose, Critique, and Manifesto

This paper looks at the history of money and its modern form from a scientific and mathematical point of view. The approach here is to emphasize simplicity. A straightforward model and algebraic formula for a large economy analogous to the ideal gas law of thermodynamics is proposed. It may be something like a new ``F=ma'' rule of the emerging econophysics field. Some implications of the equation are outlined, derived, and proved. The phenomena of counterfeiting, inflation and deflation are analyzed for interrelations. Analogies of the economy to an ecosystem or energy system are advanced. The fundamental legitimacy of ``expansion of the money supply'' in particular is re-examined and challenged. From the hypotheses a major (admittedly radical) conclusion is that the modern international ``fractional reserve banking system'' is actually equivalent to ``legalized economic parasitism by private bankers.'' This is the case because, contrary to conventional wisdom, the proceeds of inflation are not actually spendable by the state. Also possible are forms of ``economic warfare'' based on the principles. Alternative systems are proposed to remediate this catastrophic flaw.fractional reserve banking money expansion parasitism capitalism greenspan gold thermodynamics perfect gas econophysics gresham's law stiglitz money supply inflation deflation growth price stability counterfeiting energy radical polemic revolution economic warfare religion doublespeak gdp scarcity fiat blips federal reserve history slavery lassaiz-fair solow keynes keynesianism cancer psychology sociology politics analogy IMF world bank GNP GDP digital cash money laundering pareto mcfadden echelon nsa free market growth conspiracy

Air Traffic Control

Improving air traffic control and air traffic management is currently one of the top priorities of the global research and development agenda. Massive, multi-billion euro programs like SESAR (Single European Sky ATM Research) in Europe and NextGen (Next Generation Air Transportation System) in the United States are on their way to create an air transportation system that meets the demands of the future. Air traffic control is a multi-disciplinary field that attracts the attention of many researchers, ranging from pure mathematicians to human factors specialists, and even in the legal and financial domains the optimization and control of air transport is extensively studied. This book, by no means intended to be a basic, formal introduction to the field, for which other textbooks are available, includes nine chapters that demonstrate the multi-disciplinary character of the air traffic control domain

Security at the Edge

The Internet has become an essential part of daily life for almost everyone in society having grown far beyond its roots in the 1970s as the ARPANET, a network that was principally the domain of scientists and engineers. The popularity of the HTTP, developed at CERN in the late 1980s led to the widespread use of the term ‘the web’ as a generic name for the Internet for many years, at least in the public domain. Of course, the Internet is much more than just web browsing and, in recent years, the term cyberspace has become the most popular term to describe interactions over the Internet. Yet, an unambiguous definition of the term is difficult to formulate . Financial institutions underpinning the economy and the operation of national critical infrastructures, such as monitoring and control of the electricity supply, are now dependent on the Internet. A consequence of this is that cyberattacks become more costly for the victims and perversely more attractive to the criminals who carry them out . The advent of the Internet of Things (IoT) and edge computing as a new paradigm creates the potential for enhanced productivity but at the same time opens up new opportunities for cyberattacks while still being exposed to existing attach vectors such as the well-known denial of service attack (DDoS), which can take place in many forms . In this chapter, we described the challenges in building an edge system that is secure against cyberattack. We begin by briefly reviewing the architecture of communications over the Internet and later consider the new challenges that follow from operating the hardware with values of voltage, frequency and current that enable more energy efficiency

Recent Advances in Social Data and Artificial Intelligence 2019

The importance and usefulness of subjects and topics involving social data and artificial intelligence are becoming widely recognized. This book contains invited review, expository, and original research articles dealing with, and presenting state-of-the-art accounts pf, the recent advances in the subjects of social data and artificial intelligence, and potentially their links to Cyberspace

Quantitative Methods for Economics and Finance

This book is a collection of papers for the Special Issue “Quantitative Methods for Economics and Finance” of the journal Mathematics. This Special Issue reflects on the latest developments in different fields of economics and finance where mathematics plays a significant role. The book gathers 19 papers on topics such as volatility clusters and volatility dynamic, forecasting, stocks, indexes, cryptocurrencies and commodities, trade agreements, the relationship between volume and price, trading strategies, efficiency, regression, utility models, fraud prediction, or intertemporal choice

Security Mechanisms in Unattended Wireless Sensor Networks

Wireless Sensor Networks (WSNs) consisting of a large number of sensor nodes are being deployed in potentially hostile environments for applications such as forest fire detection, battlefield surveillance, habitat monitoring, traffic management, etc. One common assumption in traditional WSNs is that a trusted third party, i.e., a sink, is assumed to be always available to collect sensed data in a real time or near real time fashion. Although many WSNs operate in such an on-site mode, there are WSN applications that do not fit into the real time data collection mode. For example, data collection in Unattended WSNs (UWSNs) relies on the periodical appearance of a mobile sink. As most existing security solutions developed for traditional WSNs rely on the presence of a trusted third party, it makes them not applicable to UWSNs directly. This motivates the research on security mechanisms for UWSNs. This dissertation contributes to security mechanisms in UWSNs from three important aspects, as, confidentiality and reliability, trust management, and capture resistance. The first aspect addresses data confidentiality and data reliability in UWSNs. We propose a data distribution scheme to provide forward secrecy, probabilistic backward secrecy and data reliability. Moreover, we demonstrate that backward secrecy of the historical data can be achieved through homomorphic encryption and key evolution. Furthermore, we propose a constrained optimization algorithm to further improve the above two data distribution schemes. The second study introduces trust management in UWSNs. We propose a set of efficient and robust trust management schemes for the case of UWSNs. The Advanced Scheme utilizes distributed trust data storage to provide trust data reliability and takes the advantages of both Geographic Hash Table (GHT) and Greedy Perimeter Stateless Routing (GPSR) to find storage nodes and to route trust data to them. In this way, it significantly reduces storage cost caused by distributed trust data storage and provides resilience to node compromise and node invalidation. The third study investigates how to detect a captured node and to resist node capture attack in UWSNs. We propose a node capture resistance and key refreshing scheme for UWSNs based on the Chinese remainder theorem. The scheme is able to provide forward secrecy, backward secrecy and collusion resistance for diminishing the effects of capture attacks

Essays in High Frequency Trading and Market Structure

High Frequency Trading (HFT) is the use of algorithmic trading technology to gain a speed advantage when operating in financial markets. The increasing gap between the fastest and the slowest players in financial markets raises questions around the efficiency of markets, the strategies players must use to trade effectively and the overall fairness of markets which regulators must maintain. This research explores markets affected by HFT activity from three perspectives. Firstly an updated microstructure model is proposed to allow for empirical exploration of current levels of noise in financial markets, this illustrates current noise levels are not disruptive to dominant trading strategies. Second, a ARCH type model is used to de-compose market data into a series of traders working price levels to demonstrate that in cases of suspected market abuse, regulators can assess the impact individual traders make on price even in fast markets. Finally, a review of various HFT control measures are examined in terms of effectiveness and in light of an ordoliberal benchmark of fairness. The work illustrates the extents to which HFT activity is not yet disruptive, but also shows where HFT can be a conduit for market abuse and provides a series of recommendations around use of circuit breakers, algorithmic governance standards and additional considerations where assets are dual listed in different countries