Troy Hunt: The 773 Million Record "Collection #1" Data Breach
Let's start with the raw numbers because that's the headline, then I'll drill down into where it's from and what it's composed of. Collection #1 is a set of email addresses and passwords totalling 2,692,818,238 rows. It's made up of many different individual data breaches from literally thousands of different sources. (And yes, fellow techies, that's a sizeable amount more than a 32-bit integer can hold.)
In total, there are 1,160,253,228 unique combinations of email addresses and passwords. This is when treating the password as case sensitive but the email address as not case sensitive. This also includes some junk because hackers being hackers, they don't always neatly format their data dumps into an easily consumable fashion. (I found a combination of different delimiter types including colons, semicolons, spaces and indeed a combination of different file types such as delimited text files, files containing SQL statements and other compressed archives.)
The unique email addresses totalled 772,904,991. This is the headline you're seeing as this is the volume of data that has now been loaded into Have I Been Pwned (HIBP). It's after as much clean-up as I could reasonably do and per the previous paragraph, the source data was presented in a variety of different formats and levels of "cleanliness". This number makes it the single largest breach ever to be loaded into HIBP.
There are 21,222,975 unique passwords. As with the email addresses, this was after implementing a bunch of rules to do as much clean-up as I could including stripping out passwords that were still in hashed form, ignoring strings that contained control characters and those that were obviously fragments of SQL statements. Regardless of best efforts, the end result is not perfect nor does it need to be. It'll be 99.x% perfect though and that x% has very little bearing on the practical use of this data. And yes, they're all now in Pwned Passwords, more on that soon.