0101.no

In reference to the latest “Swedish password hacking scandal“:

MD5 hashed password are still widely used for storing passwords in  a database. Here’s Andrew Moore‘s contribution to help prevent this in the future, using Bcrypt. If you don’t have BCrypt installed, use phppass

<?php

class Bcrypt {
private $rounds;
public function __construct($rounds = 12) {
if(CRYPT_BLOWFISH != 1) {
throw new Exception(“bcrypt not supported in this installation. See http://php.net/crypt”);
}

$this->rounds = $rounds;
}

public function hash($input) {
$hash = crypt($input, $this->getSalt());

if(strlen($hash) > 13)
return $hash;

return false;
}

public function verify($input, $existingHash) {
$hash = crypt($input, $existingHash);

return $hash === $existingHash;
}

private function getSalt() {
$salt = sprintf(‘$2a$%02d$’, $this->rounds);

$bytes = $this->getRandomBytes(16);

$salt .= $this->encodeBytes($bytes);

return $salt;
}

private $randomState;
private function getRandomBytes($count) {
$bytes = ”;

if(function_exists(‘openssl_random_pseudo_bytes’) &&
(strtoupper(substr(PHP_OS, 0, 3)) !== ‘WIN’)) { // OpenSSL slow on Win
$bytes = openssl_random_pseudo_bytes($count);
}

if($bytes === ” && is_readable(‘/dev/urandom’) &&
($hRand = @fopen(‘/dev/urandom’, ‘rb’)) !== FALSE) {
$bytes = fread($hRand, $count);
fclose($hRand);
}

if(strlen($bytes) < $count) {
$bytes = ”;

if($this->randomState === null) {
$this->randomState = microtime();
if(function_exists(‘getmypid’)) {
$this->randomState .= getmypid();
}
}

for($i = 0; $i < $count; $i += 16) {
$this->randomState = md5(microtime() . $this->randomState);

if (PHP_VERSION >= ’5′) {
$bytes .= md5($this->randomState, true);
} else {
$bytes .= pack(‘H*’, md5($this->randomState));
}
}

$bytes = substr($bytes, 0, $count);
}

return $bytes;
}

private function encodeBytes($input) {
// The following is code from the PHP Password Hashing Framework
$itoa64 = ‘./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789′;

$output = ”;
$i = 0;
do {
$c1 = ord($input[$i++]);
$output .= $itoa64[$c1 >> 2];
$c1 = ($c1 & 0×03) << 4;
if ($i >= 16) {
$output .= $itoa64[$c1];
break;
}

$c2 = ord($input[$i++]);
$c1 |= $c2 >> 4;
$output .= $itoa64[$c1];
$c1 = ($c2 & 0x0f) << 2;

$c2 = ord($input[$i++]);
$c1 |= $c2 >> 6;
$output .= $itoa64[$c1];
$output .= $itoa64[$c2 & 0x3f];
} while (1);

return $output;
}
}

$bcrypt = new Bcrypt(10);
$password = “agoodpassword”;echo $password;
$hash = $bcrypt->hash($password);echo ” = “.$hash.”<br>”;
$isGood = $bcrypt->verify(‘agoodpassword’, $hash);
if ($isGood) echo “OK<br/><br/>”;
else echo “NOT OK<br/><br/>”;

//Look, same password, different output! Mmmm, salt.

$bcrypt = new Bcrypt(10);
$password = “agoodpassword”;echo $password;
$hash = $bcrypt->hash($password);echo ” = “.$hash.”<br>”;
$isGood = $bcrypt->verify(‘agoodpassword’, $hash);
if ($isGood) echo “OK<br/><br/>”;
else echo “NOT OK<br/><br/>”;

?>