why?

• Direct access to the affected account
• May compromise other accounts (email, bank, etc)
• Add password cracking corpus

how?

• Server Hacked (Gawker 2010)
• Vulnerability in Site (RockYou 2009)
• Database Backup Stolen (Bitly 2014)

let's look at how

passwords are being stored...

but why would you ever?

• Really easy to implement (lazy)
• Allows for easy password recovery
• Straightforward, simple comparison

NEVER use plaintext

but who is that stupid?

• 30% of websites store passwords in plaintext
• MySpace, RockYou, Hotmail
• If they know your password, they're storing plaintext

Reversible Encryption

now what?

Hashing

Specifically, a "one-way cryptographic hash"

password123

8640bd46

password123

8640bd46

but what about password?

 how do it know?

We don't know the password, but we can still authenticate the user with her password

win?

password123

8640bd46

digest

input

Salting

• Salts are public, stored as plaintext
• Every user has a different, random salt

Salting

why is this better?

• You have to try every combination on each user 
• a hit only applies to one user

password123

7fc7c392

e73f51aa

password123

a778eef2

53026489

password123

b8d12a9a

160bba71

user 1:

user 2:

user 3:

MD5 vs bcrypt

• MD5​
  • Designed to be fast and efficient
  • GPU accelerated
• bcrypt
  • Designed to be slow and resource intensive
  • CPU only (can't be accelerated)

MD5 vs bcrypt

Ashley Madison used bcrypt

/giphy shrug

fin.