Privacy Pass helps to make solving CAPTCHAs online less painful using zero-knowledge cryptography. This project was done in collaboration with researchers from Royal Holloway and the University of Waterloo. The core of Privacy Pass is a 1-RTT cryptographic protocol (based on an implementation of an oblivious pseudorandom function) that allows users to receive an amount of unlinkable tokens in exchange for solving a CAPTCHA challenge. Users can redeem tokens in the future for accessing to services without having to interact with a challenge, and the service cannot link the redeemed token to previously-issued tokens.
- Privacy Pass v3: the new privacy bits
- Supporting the latest version of the Privacy Pass Protocol
- Privacy Pass - “The Math”
- Cloudflare supports Privacy Pass