Source for file password.php

Documentation is available at password.php

<?php
/**
* A Compatibility library with PHP 5.5's simplified password hashing API.
*
* @author Anthony Ferrara <ircmaxell@php.net>
* @contributor Laurent Jouanneau <laurent@jelix.org>
* @license http://www.opensource.org/licenses/mit-license.html MIT License
*/
/**
* function to check if the password API can be used
* In some PHP version ( <5.3.7), crypt() with blowfish is vulnerable.
* But this issue has been fixed on some older PHP version (php 5.3.3 for most of them) in some
* distro, like Debian squeeze.
* @see http://www.php.net/security/crypt_blowfish.php
*/
function can_use_password_API () {
if (version_compare(PHP_VERSION, '5.3.7', '>=')) {
if (!defined('_PASSWORD_CRYPT_HASH_FORMAT'))
define('_PASSWORD_CRYPT_HASH_FORMAT', '$2y$%02d$');
if (!defined('_PASSWORD_CRYPT_PROLOG'))
define('_PASSWORD_CRYPT_PROLOG', '$2y$');
return true;
}
if (version_compare(PHP_VERSION, '5.3.3', '<')) {
return false;
}
// On debian squeeze, crypt() has been fixed in PHP 5.3.3
// http://security-tracker.debian.org/tracker/CVE-2011-2483
// so we can use crypt() securely with $2a$ ($2y$ is not available)
if (preg_match('/squeeze(\d+)$/', PHP_VERSION, $m)) {
if (intval($m[1]) >= 4) {
if (!defined('_PASSWORD_CRYPT_HASH_FORMAT'))
define('_PASSWORD_CRYPT_HASH_FORMAT', '$2a$%02d$');
if (!defined('_PASSWORD_CRYPT_PROLOG'))
define('_PASSWORD_CRYPT_PROLOG', '$2a$');
return true;
}
}
//FIXME crypt() in PHP 5.3.3 is fixed also on other distro like RedHat.
// however I don't know if it supports 2y, and how does PHP_VERSION look like
return false;
}
if (!can_use_password_API()) {
trigger_error("The Password Compatibility Library requires PHP >= 5.3.7 or PHP >= 5.3.3-7+squeeze4 on debian", E_USER_WARNING);
// Prevent defining the functions
return;
}
if (!defined('PASSWORD_BCRYPT')) {
define('PASSWORD_BCRYPT', 1);
define('PASSWORD_DEFAULT', PASSWORD_BCRYPT);
/**
* Hash the password using the specified algorithm
*
* @param string $password The password to hash
* @param int $algo The algorithm to use (Defined by PASSWORD_* constants)
* @param array $options The options for the algorithm to use
*
* @returns string|false The hashed password, or false on error.
*/
function password_hash($password, $algo, array $options = array()) {
if (!function_exists('crypt')) {
trigger_error("Crypt must be loaded for password_hash to function", E_USER_WARNING);
return null;
}
if (!is_string($password)) {
trigger_error("password_hash(): Password must be a string", E_USER_WARNING);
return null;
}
if (!is_int($algo)) {
trigger_error("password_hash() expects parameter 2 to be long, " . gettype($algo) . " given", E_USER_WARNING);
return null;
}
switch ($algo) {
case PASSWORD_BCRYPT:
// Note that this is a C constant, but not exposed to PHP, so we don't define it here.
$cost = 10;
if (isset($options['cost'])) {
$cost = $options['cost'];
if ($cost < 4 || $cost > 31) {
trigger_error(sprintf("password_hash(): Invalid bcrypt cost parameter specified: %d", $cost), E_USER_WARNING);
return null;
}
}
$required_salt_len = 22;
$hash_format = sprintf(_PASSWORD_CRYPT_HASH_FORMAT, $cost);
break;
default:
trigger_error(sprintf("password_hash(): Unknown password hashing algorithm: %s", $algo), E_USER_WARNING);
return null;
}
if (isset($options['salt'])) {
switch (gettype($options['salt'])) {
case 'NULL':
case 'boolean':
case 'integer':
case 'double':
case 'string':
$salt = (string) $options['salt'];
break;
case 'object':
if (method_exists($options['salt'], '__tostring')) {
$salt = (string) $options['salt'];
break;
}
case 'array':
case 'resource':
default:
trigger_error('password_hash(): Non-string salt parameter supplied', E_USER_WARNING);
return null;
}
if (strlen($salt) < $required_salt_len) {
trigger_error(sprintf("password_hash(): Provided salt is too short: %d expecting %d", strlen($salt), $required_salt_len), E_USER_WARNING);
return null;
} elseif (0 == preg_match('#^[a-zA-Z0-9./]+$#D', $salt)) {
$salt = str_replace('+', '.', base64_encode($salt));
}
} else {
$buffer = '';
$raw_length = (int) ($required_salt_len * 3 / 4 + 1);
$buffer_valid = false;
if (function_exists('mcrypt_create_iv')) {
$buffer = mcrypt_create_iv($raw_length, MCRYPT_DEV_URANDOM);
if ($buffer) {
$buffer_valid = true;
}
}
if (!$buffer_valid && function_exists('openssl_random_pseudo_bytes')) {
$buffer = openssl_random_pseudo_bytes($raw_length);
if ($buffer) {
$buffer_valid = true;
}
}
if (!$buffer_valid && file_exists('/dev/urandom')) {
$f = @fopen('/dev/urandom', 'r');
if ($f) {
$read = strlen($buffer);
while ($read < $raw_length) {
$buffer .= fread($f, $raw_length - $read);
$read = strlen($buffer);
}
fclose($f);
if ($read >= $raw_length) {
$buffer_valid = true;
}
}
}
if (!$buffer_valid || strlen($buffer) < $raw_length) {
$bl = strlen($buffer);
for ($i = 0; $i < $raw_length; $i++) {
if ($i < $bl) {
$buffer[$i] = $buffer[$i] ^ chr(mt_rand(0, 255));
} else {
$buffer .= chr(mt_rand(0, 255));
}
}
}
$salt = str_replace('+', '.', base64_encode($buffer));
}
$salt = substr($salt, 0, $required_salt_len);
$hash = $hash_format . $salt;
$ret = crypt($password, $hash);
if (!is_string($ret) || strlen($ret) <= 13) {
return false;
}
return $ret;
}
/**
* Get information about the password hash. Returns an array of the information
* that was used to generate the password hash.
*
* array(
* 'algo' => 1,
* 'algoName' => 'bcrypt',
* 'options' => array(
* 'cost' => 10,
* ),
* )
*
* @param string $hash The password hash to extract info from
*
* @return array The array of information about the hash.
*/
function password_get_info($hash) {
$return = array(
'algo' => 0,
'algoName' => 'unknown',
'options' => array(),
);
if (substr($hash, 0, 4) == _PASSWORD_CRYPT_PROLOG && strlen($hash) == 60) {
$return['algo'] = PASSWORD_BCRYPT;
$return['algoName'] = 'bcrypt';
list($cost) = sscanf($hash, _PASSWORD_CRYPT_HASH_FORMAT);
$return['options']['cost'] = $cost;
}
return $return;
}
/**
* Determine if the password hash needs to be rehashed according to the options provided
*
* If the answer is true, after validating the password using password_verify, rehash it.
*
* @param string $hash The hash to test
* @param int $algo The algorithm used for new password hashes
* @param array $options The options array passed to password_hash
*
* @return boolean True if the password needs to be rehashed.
*/
function password_needs_rehash($hash, $algo, array $options = array()) {
$info = password_get_info($hash);
if ($info['algo'] != $algo) {
return true;
}
switch ($algo) {
case PASSWORD_BCRYPT:
$cost = isset($options['cost']) ? $options['cost'] : 10;
if ($cost != $info['options']['cost']) {
return true;
}
break;
}
return false;
}
/**
* Verify a password against a hash using a timing attack resistant approach
*
* @param string $password The password to verify
* @param string $hash The hash to verify against
*
* @return boolean If the password matches the hash
*/
function password_verify($password, $hash) {
if (!function_exists('crypt')) {
trigger_error("Crypt must be loaded for password_verify to function", E_USER_WARNING);
return false;
}
$ret = crypt($password, $hash);
if (!is_string($ret) || strlen($ret) != strlen($hash) || strlen($ret) <= 13) {
return false;
}
$status = 0;
for ($i = 0; $i < strlen($ret); $i++) {
$status |= (ord($ret[$i]) ^ ord($hash[$i]));
}
return $status === 0;
}
}

Documentation generated on Thu, 19 Sep 2013 00:09:01 +0200 by phpDocumentor 1.4.3