Instantaneous Decentralized Poker

We present efficient protocols for amortized secure multiparty computation with penalties and secure cash distribution, of which poker is a prime example. Our protocols have an initial phase where the parties interact with a cryptocurrency network, that then enables them to interact only among themselves over the course of playing many poker games in which money changes hands. The high efficiency of our protocols is achieved by harnessing the power of stateful contracts. Compared to the limited expressive power of Bitcoin scripts, stateful contracts enable richer forms of interaction between standard secure computation and a cryptocurrency. We formalize the stateful contract model and the security notions that our protocols accomplish, and provide proofs using the simulation paradigm. Moreover, we provide a reference implementation in Ethereum/Solidity for the stateful contracts that our protocols are based on. We also adopt our off-chain cash distribution protocols to the special case of stateful duplex micropayment channels, which are of independent interest. In comparison to Bitcoin based payment channels, our duplex channel implementation is more efficient and has additional features

The Evolution of Embedding Metadata in Blockchain Transactions

The use of blockchains is growing every day, and their utility has greatly expanded from sending and receiving crypto-coins to smart-contracts and decentralized autonomous organizations. Modern blockchains underpin a variety of applications: from designing a global identity to improving satellite connectivity. In our research we look at the ability of blockchains to store metadata in an increasing volume of transactions and with evolving focus of utilization. We further show that basic approaches to improving blockchain privacy also rely on embedding metadata. This paper identifies and classifies real-life blockchain transactions embedding metadata of a number of major protocols running essentially over the bitcoin blockchain. The empirical analysis here presents the evolution of metadata utilization in the recent years, and the discussion suggests steps towards preventing criminal use. Metadata are relevant to any blockchain, and our analysis considers primarily bitcoin as a case study. The paper concludes that simultaneously with both expanding legitimate utilization of embedded metadata and expanding blockchain functionality, the applied research on improving anonymity and security must also attempt to protect against blockchain abuse.Comment: 9 pages, 6 figures, 1 table, 2018 International Joint Conference on Neural Network

TumbleBit: an untrusted Bitcoin-compatible anonymous payment hub

This paper presents TumbleBit, a new unidirectional unlinkable payment hub that is fully compatible with today s Bitcoin protocol. TumbleBit allows parties to make fast, anonymous, off-blockchain payments through an untrusted intermediary called the Tumbler. TumbleBits anonymity properties are similar to classic Chaumian eCash: no one, not even the Tumbler, can link a payment from its payer to its payee. Every payment made via TumbleBit is backed by bitcoins, and comes with a guarantee that Tumbler can neither violate anonymity, nor steal bitcoins, nor print money by issuing payments to itself. We prove the security of TumbleBit using the real/ideal world paradigm and the random oracle model. Security follows from the standard RSA assumption and ECDSA unforgeability. We implement TumbleBit, mix payments from 800 users and show that TumbleBits offblockchain payments can complete in seconds.https://eprint.iacr.org/2016/575.pdfPublished versio

Financial Accounting Classification of Cryptocurrency

Currently, a large range of opinions exists regarding the appropriate classification and regulation of cryptocurrency. From the legal perspective, some suggest that cryptocurrency investments are too speculative. As a result of this, it is suggested that cryptocurrency should be more heavily regulated. This would be done to prevent speculators from losing vast wealth. Other legal analysts suggest that an increasing cryptocurrency regulation would have a detrimental effect on the state of cryptocurrency, and its use would cause long-term problems. From the accounting perspective, opinions vary. Some suggest an accounting classification that would make cryptocurrency cash equivalents; others suggest an accounting classification that would render cryptocurrency an intangible asset with an indefinite useful life. The “big 4” accounting firms that include Deloitte, PricewaterhouseCoopers, Ernst and Young, and KPMG recommend that cryptocurrency should be classified as an intangible asset with an indefinite useful life. However, other companies currently using cryptocurrency through the general operations of the business have decided to classify it differently. The legal perspectives and the accounting perspectives will be analyzed to determine appropriate regulations for cryptocurrency and an appropriate classification for cryptocurrency. The results will show that cryptocurrency should be classified as an intangible asset with an indefinite useful life for accounting purposes and as property for tax purposes

What Do We Know about Gender and Other Social Impacts of IWS Projects?: A Literature Review

The approach of this short literature review is to look firstly at what the literature has to say about wider social impacts of "investing in watershed services" (IWS) projects or programs and, secondly, to examine more specifically the gender issues. The term IWS is used in this paper as a convenient shorthand while realizing that this is a controversial term and that there is a case for using other terms such as "payments for watershed services", "reciprocal arrangements in watershed service provision" or "compensation for provision of watershed services." In the interest of brevity, this discussion is not entered into except to say that the term IWS is used here in a broad and inclusive way similar to "IWS-like schemes" as used in the Bellagio Conversations (Asquith & Wunder 2008)

Anonymous network access using the digital marketplace

With increasing usage of mobile telephony, and the trend towards additional mobile Internet usage, privacy and anonymity become more and more important. Previously-published anonymous communication schemes aim to obscure their users' network addresses, because real-world identity can be easily be derived from this information. We propose modifications to a novel call-management architecture, the digital marketplace, which will break this link, therefore enabling truly anonymous network access