Google Chrome has added a new Extension called Password Checkup that can automatically determine if a user’s passwords have been exposed in a data breach. The extension checks any login details you use — Google says “most” US sites are supported — against a database of around four billion usernames and passwords and warns you if it finds a match.
Password breaches are an unfortunately common occurrence, but so long as you’re using a unique password for each website it’s normally fairly simple to deal with. Just change the login credentials used with the breached website, and move on. Unfortunately, when massive breaches like Collection #1 compromise so many different passwords it can be impossible to know which of yours are still safe. That’s where Google’s new extension comes in.
Since Password Checkup relies on sending your confidential information to Google, the company is keen to emphasize that this is encrypted and that it has no way of seeing your data. Passwords in the database are stored in a hashed and encrypted form, and any warning that’s generated about your details is entirely local to your machine.

source: theverge.com