Checking Pwned Passwords for a Password Offline
Perusing ArsTechnica a couple of weeks back, my eye was caught by this article about a recent dump of emails and password circulating on hacking forums, referred to as Collection #1. Collection #1 is a collection of 773 million unique email addresses and 21 million unique passwords thought to be an amalgamation of several historical hacks but also containing around 140 million email addresses not previously seen in dumps like this.