Privacy-Preserving Compromised Credential Checking

Today we’re announcing a public demo and an open-sourced Go implementation of a next-generation, privacy-preserving compromised credential checking protocol called MIGP (“Might I Get Pwned”, a nod to Troy Hunt’s “Have I Been Pwned”). Compromised credential checking services are used to alert users when their credentials might have been exposed in data breaches. Critically, the ‘privacy-preserving’ property of the MIGP protocol means that clients can check for leaked credentials without leaking any information to the service about the queried password, and only a small amount of information about the queried username. Thus, not only can the service inform you when one of your usernames and passwords may have become compromised, but it does so without exposing any unnecessary information, keeping credential checking from becoming a vulnerability itself. The ‘next-generation’ property comes from the fact that MIGP advances upon the current state of the art in credential checking services by allowing clients to not only check if their exact password is present in a data breach, but to check if similar passwords have been exposed as well.

For example, suppose your password last year was amazon20\$, and you change your password each year (so your current password is amazon21\$). Continue reading