February 1, 2023

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. […]

Breaking, fixing, and extending zero-knowledge contingent payments

The problem of fair exchange arises often in business transactions — especially when those transactions are conducted anonymously over the internet. Alice would like to buy a widget from Bob, but there’s a circular problem: Alice refuses to pay Bob until she receives the widget whereas Bob refuses to send Alice the widget until he […]

How to buy physical goods using Bitcoin with improved security and privacy

Bitcoin has found success as a decentralized digital currency, but it is only one step toward decentralized digital commerce. Indeed, creating decentralized marketplaces and mechanisms is a nascent and active area of research. In a new paper, we present escrow protocols for cryptocurrencies that bring us closer to decentralized commerce. In any online sale of […]

Threshold signatures for Bitcoin wallets are finally here

Today we are pleased to release our paper presenting a new ECDSA threshold signature scheme that is particularly well-suited for securing Bitcoin wallets. We teamed up with cryptographer Rosario Gennaro to build this scheme. Threshold signatures can be thought of as “stealth multi-signatures.”

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 […]