- crypt: documentation ( source)
<?php
$setting = '$2a$04$';
$salt = '1234567890123456789012'; // SAME SALT FOR ALL PASSWORDS, OMG, DON'T
$passwd1 = '000000000000000000000000000000000000000000000000000000000000000000000000';
$passwd2 = '012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234';
$passwd3 = '0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345';
$hash1 = crypt($passwd1, $setting . $salt);
$hash2 = crypt($passwd2, $setting . $salt);
$hash3 = crypt($passwd3, $setting . $salt);
echo ($hash1 === $hash2 ? '1-2 same' : 'unique');
echo ($hash2 === $hash3 ? '2-3 same' : 'unique');