Alternative to crypt()

Question

I am working on a script and need to save passwords. For development purposes, I have been using the crypt() function because it was easy and available. Now that I am mostly done, I want to replace it with something a little better and more consistent.

Some of the concerns I have are:

• not all algorithms are supported on every system
• sometimes the salt is pre-pended to the result (seems like a security problem)

I want something that works with PHP 4.3+.

Is there anything available, or should I stick with crypt()? I thought about using md5(md5($password).$salt). Thanks for the insight.

Answer 1

There is nothing wrong with crypt

If your server does not support it, use another server.

You should NEVER use MD5 for hashing passwords (or even SHA1 for that matter)

Use either bcrypt (the blowfish method of crypt) or pbkdf2

There is an implementation of pbkdf2 here: Encrypting Passwords with PHP for Storage Using the RSA PBKDF2 Standard

More information on why and how here:

• Which password hashing method should I use?
• Do any security experts recommend bcrypt for password storage?

Answer 2

First of all: Prepending the salt is not a security problem. Having a per-password salt is a big goodie, and it's perfectly OK to it being store alongside the pw.

Now: As long as you don't transport password hashes from one system to another, and the latter not supporting the default algorithm of the first, nothing bad will happen by definition. Since PHP 5.3 there are built-in algorithms in PHP such as Blowfish, that are guaranteed to be available.