// A salt is randomly generated here to protect again brute force attacks 
        // and rainbow table attacks.  The following statement generates a hex 
        // representation of an 8 byte salt.  Representing this in hex provides 
        // no additional security, but makes it easier for humans to read. 
        // For more information: 
        // http://en.wikipedia.org/wiki/Salt_%28cryptography%29 
        // http://en.wikipedia.org/wiki/Brute-force_attack 
        // http://en.wikipedia.org/wiki/Rainbow_table 
        $salt = dechex(mt_rand(0, 2147483647)) . dechex(mt_rand(0, 2147483647)); 
 
        // This hashes the password with the salt so that it can be stored securely 
        // in your database.  The output of this next statement is a 64 byte hex 
        // string representing the 32 byte sha256 hash of the password.  The original 
        // password cannot be recovered from the hash.  For more information: 
        // http://en.wikipedia.org/wiki/Cryptographic_hash_function 
        $password = hash('sha256', $_POST['password'] . $salt); 
 
        // Next we hash the hash value 65536 more times.  The purpose of this is to 
        // protect against brute force attacks.  Now an attacker must compute the hash 65537 
        // times for each guess they make against a password, whereas if the password 
        // were hashed only once the attacker would have been able to make 65537 different  
        // guesses in the same amount of time instead of only one. 
        for($round = 0; $round < 65536; $round++) 
        { 
            $password = hash('sha256', $password . $salt); 
        } 
 
        // Here we prepare our tokens for insertion into the SQL query.  We do not 
        // store the original password; only the hashed version of it.  We do store 
        // the salt (in its plaintext form; this is not a security risk).