WebAppSec/Secure Coding Guidelines: Difference between revisions

WebAppSec/Secure Coding Guidelines (view source)

Revision as of 16:17, 12 October 2011

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Pls email me to discuss - Undo revision 357366 by Yorickpeterse (talk)

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 ===Password Storage===
+Separate from the password policy, we should have the following standards when it comes to storing passwords:
+* Passwords stored in a database should using the hmac+bcrypt function.
-Passwords stored in a database should use [https://en.wikipedia.org/wiki/Bcrypt
+The purpose of hmac and bcrypt storage is as follows:
-bcrypt].Bcrypt is a hashing algorithm designer to keep up with Moore's law.
+* bcrypt provides a hashing mechanism which can be configured to consume sufficient time to prevent brute forcing of hash values even with many computers
-General hashing algorithms such as SHA512 can be used to generate hashes very
+* bcrypt can be easily adjusted at any time to increase the amount of work and thus provide protection against more powerful systems
-fast depending on the hardware used. If computer B is 10 times faster than
+* The nonce for the hmac value is designed to be stored on the file system and not in the databases storing the password hashes. In the event of a compromise of hash values due to SQL injection, the nonce will still be an unknown value since it would not be compromised from the file system. This significantly increases the complexity of brute forcing the compromised hashes considering both bcrypt and a large unknown nonce value
-computer A then a SHA512 hash will be generated 10 times faster on computer B
+* The hmac operation is simply used as a secondary defense in the event there is a design weakness with bcrypt that could leak information about the password or aid an attacker
-than on computer A. With bcrypt this isn't the case as it introduces a cost
-factor. Using this cost factor you can specify how long it should take to
-generate a hash regardless of how powerful a computer is.
-There are quite a few resources available on the internet on Bcrypt, below are
+A sample of this code is here: https://github.com/fwenzel/django-sha2
-a few ones that I consider worth reading:
-* http://codahale.com/how-to-safely-store-a-password/
-* http://yorickpeterse.com/articles/use-bcrypt-fool/
-* https://en.wikipedia.org/wiki/Bcrypt
 Keep in mind that while bcrypt is secure you should still enforce good passwords.