Password Security - From Zero to Hero

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Password Security From Zero to Hero @rdegges

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I’m Randall Degges Developer Evangelist, Stormpath https://stormpath.com Pythonista 103 github projects, mostly python

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“Why should I care about password security?”

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Nobody teaches it :(

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Everyone messes it up!

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LOVE YOUR USERS

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Security Samurai YOU

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The Basics

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You need to store passwords.

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Plain Text "rdegges","omgmypass" "rocketspaceadmin","abc123" "liljohn","OKKAAAYYYY!"

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This sucks.

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If someone gets access to your database, game over.

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Then you have to deal with this.

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“But Randall, who would do that?”

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...

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http://plaintextoffenders.com

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Introducing the Hash

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“What is a hash?”

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It’s basically a stupid function that converts a string into garbage.

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"rdegges","omgmypass" "rocketspaceadmin","abc123" "liljohn","OKKAAAYYYY!" "rdegges","3e3faeabbd3e98c6cedb91ad46551014" "rocketspaceadmin","e99a18c428cb38d5f260853678922e03" "liljohn","9bc50c01de2edd2bdc488d94751b4a1e" hash()

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All hashes are unique.

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You cannot ‘reverse’ a hash.

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There are lots of hashing algorithms! MD5 SHA1 SHA256 SHA512 PBKDF2 BCRYPT SCRYPT

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Most suck though. MD5 SHA1 SHA256 SHA512 PBKDF2 BCRYPT SCRYPT

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Let’s talk about why.

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Brute Force

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You basically just try every possible password.

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from hashlib import md5 from itertools import chain, product from string import printable from sys import argv def bruteforce(length): return ( ''.join(candidate) for candidate in chain.from_iterable( product( printable, repeat = i ) for i in range(1, length + 1) ) ) for pw in bruteforce(int(argv[2])): if md5(pw).hexdigest() == argv[1]: print 'Cracked hash: %s!' % argv[1] print 'Password is: %s' % pw break

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No content

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brutal! >>> from brute import brute >>> for s in brute(length=10): ... print s $ pip install brute

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Rainbow Tables

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password | md5 | sha1 -------------+----------------------------------+------------------------------------------ omgmypass | 364a7aeccbc2b0f8b9bcf07ae0dd4748 | 8a4dd43ae7291b91f995f6d3153e926211ebae44 abc123 | e99a18c428cb38d5f260853678922e03 | 6367c48dd193d56ea7b0baad25b19455e529f5ee OKKAAAYYYY! | 9bc50c01de2edd2bdc488d94751b4a1e | 9a1dc4294bbc5f6a35b5eed899386a2035a2ebde A big ass database of passwords and hashes.

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TONS of these.

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Collisions What happens when two different passwords have the same password hash.

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Salts

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You basically just create a random string and prepend it to passwords to make brute forcing harder.

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hash(salt+pass)

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salt$hash(salt+pass) hash(pass)

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"rdegges","salt$hash" "rocketspaceadmin","salt$hash" "liljohn","salt$hash"

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Salts are great because attackers can’t use rainbow tables, and must brute force every password individually.

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Speeeeeeeeeed!

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Slower is better.

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The slower a hash function is, the longer it takes to brute force.

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md5(pass) ~ .1 sec bcrypt(pass) ~ 2 sec = 20x slower

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bcrypt is slow “I’m slow.”

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>>> from bcrypt import gensalt, hashpw >>> >>> hash = hashpw('omghi!', gensalt()) >>> if hashpw('omghi!', hash) == hash: ... print 'password valid!' ... 'password valid!'

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bcrypt ● Been around for a long time. ● Very well peer reviewed. ● Widely considered the best option for password hashing. ● Easy to use in Python. ● Orders of magnitude slower than almost every other hashing function (ask me more about this later).

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“Use bcrypt or I will be upset with you.” -Randall

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$ pip install bcrypt

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# settings.py PASSWORD_HASHERS = ( 'django.contrib.auth.hashers.BCryptSHA256PasswordHasher', 'django.contrib.auth.hashers.BCryptPasswordHasher', 'django.contrib.auth.hashers.PBKDF2PasswordHasher', 'django.contrib.auth.hashers.PBKDF2SHA1PasswordHasher', 'django.contrib.auth.hashers.SHA1PasswordHasher', 'django.contrib.auth.hashers.MD5PasswordHasher', 'django.contrib.auth.hashers.CryptPasswordHasher', )

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Security is hard.

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Stormpath User Management API for Developers ● Authentication ● User Profiles ● Groups and Roles ● Awesome Python Support ● API Authentication ● Social Login ● SSO ● Hosted Login

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So... ● Store passwords with bcrypt. ● Check out stormpath.com and play around with it! It’s awesome! ● If you liked this talk, tweet @gostormpath.

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You are Awesome randall@stormpath.com @rdegges