How Meta is improving password security and preserving privacy

What this post added

Introduced Private Data Lookup (PDL), a system based on Private Set Intersection (PSI) for privacy-preserving password prechecks. PDL allows users to privately query a server-side dataset of compromised passwords without revealing their attempted passwords to Meta. Optimized the initial implementation by pre-processing compromised password data, sharding the dataset, and compressing blinded hash values to reduce latency and bandwidth usage. This enables stronger password security by proactively checking against breached passwords while minimizing data collection.