Aaron Toponce

Just this morning, security researcher Troy Hunt released a ZIP containing 306 million passwords that he's collected over the years from his ';--have i been pwned? service. As an extension, he created a service to provide either a password or a SHA-1 hash to see if your password has been pwnd.

In 2009, the social network RockYou was breached, and 32 million accounts of usernames and passwords was released to the public Internet. No doubt those 32 million passwords are included in Troy Hunt's password dump. What's interesting, and the point of this post, is individually, each password from the RockYou breach will fail.

However, what would happen if you took 6 random RockYou passwords, and created a passphrase? Below is screenshot demonstrating just that using the above 6 randomly chosen RockYou passwords. Individually, they all fail. Combined, they pass.

Now, to be fair, I'm choosing these passwords from my personalized password generator. The list is the top 7,776 passwords from the 32 million RockYou dump. As such, you could use this list as a Diceware replacement with 5 dice. Regardless, each password is chosen at random from that list, and enough passwords are chosen to reach a 70-bits of entropy target, which happen to be 6 passwords. Mandatory screenshot below:

The point of this post, is that you can actually build a secure password for sites and services using previously breached passwords for your word list source, in this case, RockYou. The only conditions is that you have a word list large enough create a reasonable passphrase with few selections, and that the process picking the passwords for you is cryptographically random.