passwords stolen?

[fiksal]

I got a message from Google Chrome when opening the forum:


"Check your passwords

A data breach on a site or app exposed your password. Chrome recommends checking your saved passwords now.

Chrome periodically checks your passwords against lists that have been published online. When doing this, your passwords and usernames are encrypted, so they can't be read by anyone, including Google."


...Wait, how does Google check then?

[X2-Illuminatus]

wired.com: Chrome Will Automatically Scan Your Passwords Against Data Breaches

The whole point of this is security, so Google is doing all of this by comparing your encrypted credentials with an encrypted list of compromised credentials. Chrome first sends an encrypted, 3-byte hash of your username to Google, where it is compared to Google's list of compromised usernames. If there's a match, your local computer is sent a database of every potentially matching username and password in the bad credentials list, encrypted with a key from Google. You then get a copy of your passwords encrypted with two keys—one is your usual private key, and the other is the same key used for Google's bad credentials list. On your local computer, Password Checkup removes the only key it is able to decrypt, your private key, leaving your Google-key-encrypted username and password, which can be compared to the Google-key-encrypted database of bad credentials. Google says this technique, called "private set intersection," means you don't get to see Google's list of bad credentials, and Google doesn't get to learn your credentials, but the two can be compared for matches.