An extended version of this post appears on my personal site. Suppose you’re building a collaborative app, along the lines of Google Docs/Sheets/Slides, Figma, Notion, etc., but without a central server. One challenge you’ll face is the actual collaboration: when one user cha…

Blockchains are a powerful technology which allow decentralized agreement with an immutable history. Since transactions can be added, but not removed, blockchains allow distributed banking as a trustworthy alternative to central banking. A vast amount of cryptographic research on…

Many social-media and Internet-of-Things services have large numbers of tiny objects, each a few hundred bytes or less. For example, edges in Facebook’s social graph, which are needed to connect friends, posts, and images among other content, average under 100 bytes. Twitter twee…

This blog post is adapted from the Delphi blog, originally published on March 10th, 2021. Again, thank you to the Allegheny County Health Department, the DELPHI Group, Chris Scott, and Roni Rosenfeld. One of the Delphi Group’s goals is to create informative tools for healthcare o…