How to use bcrypt in PHP to safely store passwords (PHP 5.3+ only)

bcrypt.php

<?php

// secure hashing of passwords using bcrypt, needs PHP 5.3+
// see http://codahale.com/how-to-safely-store-a-password/

// salt for bcrypt needs to be 22 base64 characters (but just [./0-9A-Za-z]), see http://php.net/crypt
// just an example; please use something more secure/random than sha1(microtime) :)
$salt = substr(str_replace('+', '.', base64_encode(sha1(microtime(true), true))), 0, 22);

// 2a is the bcrypt algorithm selector, see http://php.net/crypt
// 12 is the workload factor (around 300ms on my Core i7 machine), see http://php.net/crypt
$hash = crypt('foo', '$2a$12$' . $salt);

// we can now use the generated hash as the argument to crypt(), since it too will contain $a2$12$... with a variation of the hash. No need to store the salt anymore, just the hash is enough!
var_dump($hash == crypt('foo', $hash)); // true
var_dump($hash == crypt('bar', $hash)); // false

?>