RE: [PHP-DEV] [DRAFT RFC] Adding Simplified Password Hashing API

On Wed Jun 27 12:32 PM, Arvids Godjuks wrote: > because at the moment i do not understand how salt stored in the hash itself makes hash more > secure than an unsalted one. a) In terms of 'effort' to break many passwords, there's a benefit to the salt stored in the hash itself. It's not 'more secure' but 'better/recommended' since the attacker would need to create a 'rainbow table' for each password it's trying to crack Overall, the technique offers better protection. b) In terms of 'effort' to break a single password, there's **no** benefit to the salt stored in the hash itself. If you want a single password to be really secure, don't let the attacker know the salt and keep it long: // no benefit of short salt, ~ same effort required by the attacker $password = '234'; md5($password); $salt = '1'; $password = '234'; md5($salt . $password); c) The best of both worlds: long private salt (b) + different for every user (a) $saltInpassword = $password[0]; // could be random bytes, stored in password like crypt() does $salt = 'my-long-private-value-use-all-bytes'. $saltInPassword; $password = '234'; $hash = md5($salt . $password); This one requires more effort by the attacker since the long salt forces more 'bits/guesses' to pass into md5() // require even more effort, iterate for($i = 0; $i < 1000; $i++) $hash = md5($i . $hash);