When the cookie meets the blockchain

Cryptocurrencies are portrayed as a more anonymous and less traceable method of payment than credit cards. So if you shop online and pay with Bitcoin or another cryptocurrency, how much privacy do you have? In a new paper, we show just how little.Websites including shopping sites typically have dozens of third-party trackers per site. These third parties track sensitive details of payment flows, such as the items you add to your shopping cart, and their prices, regardless of how you choose to pay. Crucially, we find that many shopping sites leak enough information about your purchase to trackers that they can link it uniquely to the payment transaction on the blockchain. From there, there are well-known ways to further link that transaction to the rest of your Bitcoin wallet addresses. You can protect yourself by using browser extensions such as Adblock Plus and uBlock Origin, and by using Bitcoin anonymity techniques like CoinJoin. These measures help, but we find that linkages are still possible.

Source: When the cookie meets the blockchain

Trust, But Verify: Why the Blockchain Needs the Law by Kevin D. Werbach :: SSRN

The blockchain could be the most consequential development in information technology since the internet. Created to support the Bitcoin digital currency, the blockchain is actually something deeper: A novel solution to the age-old human problem of trust. Its potential is extraordinary. Yet without effective governance, this approach may not promote trust at all. Wholly divorced from legal enforcement, blockchain-based systems may be counterproductive or even dangerous. And they are less insulated from the law’s reach than it seems. The central question is not how to regulate blockchains, but how blockchains regulate. They may supplement, complement, or substitute for legal enforcement. Excessive or premature application of rigid legal obligations will stymie innovation and forego opportunities to leverage technology to achieve public policy objectives. Blockchain developers and legal institutions can work together. Each must recognize the unique affordances of the other system.

Source: Trust, But Verify: Why the Blockchain Needs the Law by Kevin D. Werbach :: SSRN

BACK TO THE FUTURE: THE DECENTRALIZED WEB

We offer case studies of the following decentralized publishing projects:

  • Freedom Box, a system for personal publishing
  • Diaspora, a federated social network
  • Mastodon, a federated Twitter-like service
  • Blockstack, a distributed system for online identity services
  • IPFS (Interplanetary File System), a distributed storage service with a proposed mechanism to incentivize resource sharing
  • Solid (Social Linked Data), a linked-data protocol that could act as a back-end for data sharing between social media networks
  • Appcoins, a digital currency framework that enables users to financially participate in ownership of platforms and protocols
  • Steemit, an online community that uses an appcoin to incentivize development and community participation in a social network

Cryptocurrencies: A Brief Thematic Review by Usman W. Chohan :: SSRN

Cryptocurrencies are an area of heightened pecuniary, numismatic, technological, and investment interest, and yet a comprehensive understanding of their theories and foundations is still left wanting among many practitioners and stakeholders. This discussion paper synthesizes and summarizes the salient literature on cryptocurrencies with a view to advancing a more general understanding of their order and purpose.

Source: Cryptocurrencies: A Brief Thematic Review by Usman W. Chohan :: SSRN

Blockcerts: Using blokchain for identity management is (mostly) ridiculous // Jaap-Henk Hoepman

I was invited to speak at the Bitcoin in Education (BCINED) conference held in Groningen, September 5, 2017. Topic of my presentation: “Blockchain & Identity: Why you should avoid the blockchain like the plague“. While listening to the morning keynotes, praising the many benefits of using blockchains in education and for managing (academic) credentials in particular, I realised my message might provide a very much needed counterpoint. The short summary: using blokchain for identity management is ridiculous.

Source: Blockcerts: Using blokchain for identity management is (mostly) ridiculous // Jaap-Henk Hoepman

BlockSci: a platform for blockchain science and exploration

The Bitcoin blockchain — currently 140GB and growing — contains a massive amount of data that can give us insights into the Bitcoin ecosystem, including how users, businesses, and miners operate. Today we’re announcing BlockSci, an open-source software tool that enables fast and expressive analysis of Bitcoin’s and many other blockchains, and an accompanying working paper that explains its design and applications. Our Jupyter notebook demonstrates some of BlockSci’s capabilities.Current tools for blockchain analysis depend on general-purpose databases that have full support for transactions. But that’s unnecessary for blockchain analysis where the data structures are append-only. We take advantage of this observation in the design of our custom in-memory blockchain database as well as an analysis library.BlockSci’s core infrastructure is written in C++ and optimized for speed. (For example, traversing every transaction input and output on the Bitcoin blockchain takes only 10.3 seconds on our r4.2xlarge EC2 machine.) To make analysis more convenient, we provide Python bindings and a Jupyter notebook interface. This interface is slower, but is ideal for exploratory analyses and allows users to quickly iterate when developing new queries.The code below shows the convenience of traversing the blockchain using straightforward Python idioms, built-in currency conversion using historical exchange-rate data, and the use of pandas DataFrames for analysis and visualization..fees = [sum(block.fees) for block in chain.range(‘2017’)]times = [block.time for block in chain.range(‘2017’)]converter = blocksci.CurrencyConverter()df = pandas.DataFrame({“Fee”:fees}, index=times)df = converter.satoshi_to_currency_df(df, chain)When plotted, it results in the following graph showing the average transaction fee per block:BlockSci uses a custom data format; it comes with a parser that generates this data from the serialized blockchain format recorded by cryptocurrency nodes such as bitcoind. The parser supports incremental updates when new blocks are received, and making it easy to stay up to date with the latest version of the blockchain. We’ve used BlockSci to analyze Bitcoin, Bitcoin Cash, Litecoin, Namecoin, Dash, and ZCash; many other cryptocurrencies make no changes to the blockchain format, and so should be supported with no changes to BlockSci.In our working paper, we present four analyses that show BlockSci’s usefulness for answering research questions. We show how multisignatures unfortunately weaken privacy and confidentiality; we apply the cluster intersection attack to Dash, a privacy-focused altcoin; we analyze inefficiencies in the usage of block space; and we present improved methods for estimating of how often coins change possession as opposed to just being shuffled around.Here’s an illustrative example. Exploratory graph analysis using BlockSci allowed us to discover a behavioral pattern in the usage of multisignatures that weakens security. Multisignatures are a security-enhancing mechanism that distribute control of an address over a number of different public keys. Surprisingly, we found that users often negate this security by moving their funds from a multisig address to a regular address and then back again after a period of a few hours to days. We think this happens when users are changing the access control policy on their wallet, although it is unclear why they transfer their funds to a regular address in the interim, and not directly to the new multisig address. This pattern of behavior has led over $12 million dollars to be left insecure over the course of  over 22,000 transactions. What users may not appreciate is that the temporary weakening of security is advertised to potential attackers on the blockchain.There’s far more to explore on public blockchains. BlockSci is publicly available now, and we hope you’ll find it useful. It is easy to get started using the EC2 image we’ve released, which includes the Bitcoin blockchain data in addition to the tool. BlockSci is open-source, and we welcome contributions. This is an alpha release; we’re continuing to improve it and the interface may change a bit in future releases. We look forward to working with the community and to hearing about other creative uses of the data and the to

Source: BlockSci: a platform for blockchain science and exploration

Ryan Bubb – Overview | NYU School of Law

Ryan Bubb joined the NYU School of Law faculty in 2010. He was formerly a senior researcher for the Financial Crisis Inquiry Commission and a policy analyst at the Office of Information and Regulatory Affairs at the Office of Management and Budget. He earned a JD from Yale Law School and a PhD in political economy and government from Harvard University. Bubb’s research focuses on regulatory policy, financial institutions, business organizations, and law and economics.

Source: Ryan Bubb – Overview | NYU School of Law

Paolo Tasca – UCL Blockchain

Paolo Tasca is a Digital economist specialising in P2P financial systems. An advisor on blockchain technologies for different international organisations including the EU Parliament and the United Nations. Paolo is founder and Executive Director of the Centre for Blockchain Technologies (UCL CBT) at University College London. Prior to this, he was Lead Economist on digital currencies and P2P financial systems at Deutsche Bundesbank, Frankfurt working on digital currencies and P2P lending.

Source: Paolo Tasca – UCL Blockchain

NYU Stern – David Yermack – Albert Fingerhut Professor of Finance and Business Transformation

David L. Yermack is the Albert Fingerhut Professor of Finance and Business Transformation at New York University Stern School of Business. He serves as Chairman of the Finance Department and Director of the NYU Pollack Center for Law and Business. Professor Yermack teaches joint MBA – Law School courses in Restructuring Firms & Industries and Bitcoin & Cryptocurrencies, as well as PhD research courses in corporate governance, executive compensation, and distress and restructuring.

Source: NYU Stern – David Yermack – Albert Fingerhut Professor of Finance and Business Transformation