Category: Digital Infrastructure & Platforms
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Consensus in Bitcoin: One system, many models
At a technical level, the Bitcoin protocol is a clever solution to the consensus problem in computer science. The idea of consensus is very general — a number of participants together execute a computation to come to agreement about the state of the world, or a subset of it that they’re interested in. Because of…
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Why ASICs may be good for Bitcoin
Bitcoin mining is now almost exclusively performed by Bitcoin-specific ASICs (application-specific integrated circuits). These chips are made by a few startup manufacturers and cannot be used for anything else besides mining Bitcoin or closely related cryptocurrencies [1]. Because they are somewhere between a thousand and a million times more efficient at mining Bitcoin than a…
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Bitcoin mining is NP-hard
This post is (mostly) a theoretical curiosity, but a discussion last week at CITP during our new course on Bitcoin led us to realize that being an optimal Bitcoin miner is in fact NP-hard. NP-hardness is a complexity classification used in computer science to describe many optimization problems for which we believe there is no algorithm…
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It’s time to bring Bitcoin and cryptocurrencies into the computer science curriculum
In the privacy technologies grad seminar that I taught last semester, Bitcoin proved to be the most popular topic among students. Two groups did very different and equally interesting final projects on Bitcoin and cryptocurrencies; more on that below. More broadly, we’re seeing a huge demand for learning the computer science underlying Bitcoin, both at…
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On Decentralizing Prediction Markets and Order Books
In a new paper to be presented next week at WEIS by Jeremy Clark, we discuss the challenges in designing truly decentralized prediction markets and order books. Prediction markets allow market participants to trade shares in future events (such as “Will the USA advance to the knockout stage of the 2014 World Cup?”) and turn…
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Bitcoin Mining Now Dominated by One Pool
The big news in the Bitcoin world, is that one entity, called GHash, seems to be in control of more than half of all of the mining power. A part of Bitcoin’s appeal has been its distributed nature: the idea that no one party is in control but the system operates through the cooperative action…
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Increasing Civic Engagement Requires Understanding Why People Have Chosen Not to Participate
Last month, I was a poll watcher for the mayoral primary in Washington, DC. My duties were to monitor several polling places to confirm that each Precinct Captain was ensuring that the City’s election laws were being followed on site; in particular, that everyone who believed that they were qualified to vote was able to…
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Threshold signatures and Bitcoin wallet security: A menu of options
Before Bitcoin can mature as a currency, the security of wallets must be improved. Previously, I motivated the need for sharing Bitcoin wallets using threshold signatures as a means to greatly increase their resilience to theft. For corporate users, threshold signatures enable cryptographically secure access control. For individuals, threshold signatures can be used to build…
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The importance of anonymous cryptocurrencies
Recently I was part of a collaboration on Mixcoin, a set of proposals for improving Bitcoin’s anonymity. A natural question to ask is: why do this research? Before I address that, an even more basic question is whether or not Bitcoin is already anonymous. You may have seen back-and-forth arguments on this question. So which…
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Bitcoin hacks and thefts: The underlying reason
Emin Gün Sirer has a fascinating post about how the use of NoSQL caused technical failures that led to the demise of Bitcoin exchanges Flexcoin and Poloniex. But these are only the latest in a long line of hacks of exchanges, other services, and individuals; a wide variety of bugs have been implicated. This suggests…