Bitcoin has emerged as the most successful cryptographic currency in history. Within two years of its quiet launch in 2009, Bitcoin grew to comprise billions of dollars of economic value despite only cursory analysis of the system's design. Since then a growing literature has identified hidden-but-important properties of the system, discovered attacks, proposed promising alternatives, and singled out difficult future challenges. Meanwhile a large and vibrant open-source community has proposed and deployed numerous modifications and extensions.We provide the first systematic exposition Bitcoin and the many related cryptocurrencies or 'altcoins.' Drawing from a scattered body of knowledge, we identify three key components of Bitcoin's design that can be decoupled. This enables a more insightful analysis of Bitcoin's properties and future stability. We map the design space for numerous proposed modifications, providing comparative analyses for alternative consensus mechanisms, currency allocation mechanisms, computational puzzles, and key management tools. We survey anonymity issues in Bitcoin and provide an evaluation framework for analyzing a variety of privacy-enhancing proposals. Finally we provide new insights on what we term disintermediation protocols, which absolve the need for trusted intermediaries in an interesting set of applications. We identify three general disintermediation strategies and provide a detailed comparison. I. WHY BITCOIN IS WORTHY OF RESEARCHConsider two opposing viewpoints on Bitcoin in strawman form. The first is that "Bitcoin works in practice, but not in theory." At times devoted members of the Bitcoin community espouse this philosophy and criticize the security research community for failing to discover Bitcoin, not immediately recognizing its novelty, and still today dismissing it due to the lack of a rigorous theoretical foundation.A second viewpoint is that Bitcoin's stability relies on an unknown combination of socioeconomic factors which is hopelessly intractable to model with sufficient precision, failing to yield a convincing argument for the system's soundness. Given these difficulties, experienced security researchers may avoid Bitcoin as a topic of study, considering it prudent security engineering to only design systems with precise threat models that admit formal security proofs.We intend to show where each of these simplistic viewpoints fail. To the first, we contend that while Bitcoin has worked surprisingly well in practice so far, there is an important role for research to play in identifying precisely why this has been possible, moving beyond a blind acceptance of the informal arguments presented with the system's initial proposal. Furthermore, it is crucial to understand whether Bitcoin will still "work in practice" as practices change. We expect external political and economic factors to evolve, the system must change if and when transaction volume scales, and the nature of the monetary rewards for Bitcoin miners will change over time as part of the system design....

This paper surveys the literature of the natural resource curse hypothesis. We review the theoretical mechanisms through which natural resource wealth might slow economic growth, and then the empirical studies that test for an effect overall, or an effect on factors typically associated with economic growth. We also review more recent studies suggesting that the findings supporting the resource curse may reflect only empirical mis-specification. The literature has produced conflicting evidence, with no consensus on the net effect of natural resources in an economy. Overall we argue that evidence for a negative effect of natural resource dependence on economic growth remains convincing, particularly for developing economies and particularly working through factors closely associated with growth. We take recent contrarian studies to demonstrate, however, both that a resource curse is not inevitable, and that future studies should better address issues of endogeneity of dependence measures, years of study, and potential non-monotonic relationships.

Abstract. We propose Mixcoin, a protocol to facilitate anonymous payments in Bitcoin and similar cryptocurrencies. We build on the emergent phenomenon of currency mixes, adding an accountability mechanism to expose theft. We demonstrate that incentives of mixes and clients can be aligned to ensure that rational mixes will not steal. Our scheme is efficient and fully compatible with Bitcoin. Against a passive attacker, our scheme provides an anonymity set of all other users mixing coins contemporaneously. This is an interesting new property with no clear analog in better-studied communication mixes. Against active attackers our scheme offers similar anonymity to traditional communication mixes.

Internet users today depend daily on HTTPS for secure communication with sites they intend to visit. Over the years, many attacks on HTTPS and the certificate trust model it uses have been hypothesized, executed, and/or evolved. Meanwhile the number of browser-trusted (and thus, de facto, user-trusted) certificate authorities has proliferated, while the due diligence in baseline certificate issuance has declined. We survey and categorize prominent security issues with HTTPS and provide a systematic treatment of the history and on-going challenges, intending to provide context for future directions. We also provide a comparative evaluation of current proposals for enhancing the certificate infrastructure used in practice.

No abstract