2 /* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */
\r
5 * Random Number Generator
\r
7 * PHP versions 4 and 5
\r
9 * Here's a short example of how to use this library:
\r
12 * include('Crypt/Random.php');
\r
14 * echo bin2hex(crypt_random_string(8));
\r
18 * LICENSE: Permission is hereby granted, free of charge, to any person obtaining a copy
\r
19 * of this software and associated documentation files (the "Software"), to deal
\r
20 * in the Software without restriction, including without limitation the rights
\r
21 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
\r
22 * copies of the Software, and to permit persons to whom the Software is
\r
23 * furnished to do so, subject to the following conditions:
\r
25 * The above copyright notice and this permission notice shall be included in
\r
26 * all copies or substantial portions of the Software.
\r
28 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
\r
29 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
\r
30 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
\r
31 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
\r
32 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
\r
33 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
\r
37 * @package Crypt_Random
\r
38 * @author Jim Wigginton <terrafrost@php.net>
\r
39 * @copyright MMVII Jim Wigginton
\r
40 * @license http://www.opensource.org/licenses/mit-license.html MIT License
\r
41 * @link http://phpseclib.sourceforge.net
\r
49 define('CRYPT_RANDOM_IS_WINDOWS', strtoupper(substr(PHP_OS, 0, 3)) === 'WIN');
\r
52 * Generate a random string.
\r
54 * Although microoptimizations are generally discouraged as they impair readability this function is ripe with
\r
55 * microoptimizations because this function has the potential of being called a huge number of times.
\r
56 * eg. for RSA key generation.
\r
58 * @param Integer $length
\r
62 function crypt_random_string($length)
\r
64 if (CRYPT_RANDOM_IS_WINDOWS) {
\r
65 // method 1. prior to PHP 5.3 this would call rand() on windows hence the function_exists('class_alias') call.
\r
66 // ie. class_alias is a function that was introduced in PHP 5.3
\r
67 if (function_exists('mcrypt_create_iv') && function_exists('class_alias')) {
\r
68 return mcrypt_create_iv($length);
\r
70 // method 2. openssl_random_pseudo_bytes was introduced in PHP 5.3.0 but prior to PHP 5.3.4 there was,
\r
71 // to quote <http://php.net/ChangeLog-5.php#5.3.4>, "possible blocking behavior". as of 5.3.4
\r
72 // openssl_random_pseudo_bytes and mcrypt_create_iv do the exact same thing on Windows. ie. they both
\r
73 // call php_win32_get_random_bytes():
\r
75 // https://github.com/php/php-src/blob/7014a0eb6d1611151a286c0ff4f2238f92c120d6/ext/openssl/openssl.c#L5008
\r
76 // https://github.com/php/php-src/blob/7014a0eb6d1611151a286c0ff4f2238f92c120d6/ext/mcrypt/mcrypt.c#L1392
\r
78 // php_win32_get_random_bytes() is defined thusly:
\r
80 // https://github.com/php/php-src/blob/7014a0eb6d1611151a286c0ff4f2238f92c120d6/win32/winutil.c#L80
\r
82 // we're calling it, all the same, in the off chance that the mcrypt extension is not available
\r
83 if (function_exists('openssl_random_pseudo_bytes') && version_compare(PHP_VERSION, '5.3.4', '>=')) {
\r
84 return openssl_random_pseudo_bytes($length);
\r
87 // method 1. the fastest
\r
88 if (function_exists('openssl_random_pseudo_bytes')) {
\r
89 return openssl_random_pseudo_bytes($length);
\r
94 // warning's will be output unles the error suppression operator is used. errors such as
\r
95 // "open_basedir restriction in effect", "Permission denied", "No such file or directory", etc.
\r
96 $fp = @fopen('/dev/urandom', 'rb');
\r
98 if ($fp !== true && $fp !== false) { // surprisingly faster than !is_bool() or is_resource()
\r
99 return fread($fp, $length);
\r
101 // method 3. pretty much does the same thing as method 2 per the following url:
\r
102 // https://github.com/php/php-src/blob/7014a0eb6d1611151a286c0ff4f2238f92c120d6/ext/mcrypt/mcrypt.c#L1391
\r
103 // surprisingly slower than method 2. maybe that's because mcrypt_create_iv does a bunch of error checking that we're
\r
104 // not doing. regardless, this'll only be called if this PHP script couldn't open /dev/urandom due to open_basedir
\r
105 // restrictions or some such
\r
106 if (function_exists('mcrypt_create_iv')) {
\r
107 return mcrypt_create_iv($length, MCRYPT_DEV_URANDOM);
\r
110 // at this point we have no choice but to use a pure-PHP CSPRNG
\r
112 // cascade entropy across multiple PHP instances by fixing the session and collecting all
\r
113 // environmental variables, including the previous session data and the current session
\r
116 // mt_rand seeds itself by looking at the PID and the time, both of which are (relatively)
\r
117 // easy to guess at. linux uses mouse clicks, keyboard timings, etc, as entropy sources, but
\r
118 // PHP isn't low level to be able to use those as sources and on a web server there's not likely
\r
119 // going to be a ton of keyboard or mouse action. web servers do have one thing that we can use
\r
120 // however. a ton of people visiting the website. obviously you don't want to base your seeding
\r
121 // soley on parameters a potential attacker sends but (1) not everything in $_SERVER is controlled
\r
122 // by the user and (2) this isn't just looking at the data sent by the current user - it's based
\r
123 // on the data sent by all users. one user requests the page and a hash of their info is saved.
\r
124 // another user visits the page and the serialization of their data is utilized along with the
\r
125 // server envirnment stuff and a hash of the previous http request data (which itself utilizes
\r
126 // a hash of the session data before that). certainly an attacker should be assumed to have
\r
127 // full control over his own http requests. he, however, is not going to have control over
\r
128 // everyone's http requests.
\r
129 static $crypto = false, $v;
\r
130 if ($crypto === false) {
\r
131 // save old session data
\r
132 $old_session_id = session_id();
\r
133 $old_use_cookies = ini_get('session.use_cookies');
\r
134 $old_session_cache_limiter = session_cache_limiter();
\r
135 if (isset($_SESSION)) {
\r
136 $_OLD_SESSION = $_SESSION;
\r
138 if ($old_session_id != '') {
\r
139 session_write_close();
\r
143 ini_set('session.use_cookies', 0);
\r
144 session_cache_limiter('');
\r
147 $v = $seed = $_SESSION['seed'] = pack('H*', sha1(
\r
148 serialize($_SERVER) .
\r
149 serialize($_POST) .
\r
151 serialize($_COOKIE) .
\r
152 serialize($GLOBALS) .
\r
153 serialize($_SESSION) .
\r
154 serialize($_OLD_SESSION)
\r
156 if (!isset($_SESSION['count'])) {
\r
157 $_SESSION['count'] = 0;
\r
159 $_SESSION['count']++;
\r
161 session_write_close();
\r
163 // restore old session data
\r
164 if ($old_session_id != '') {
\r
165 session_id($old_session_id);
\r
167 ini_set('session.use_cookies', $old_use_cookies);
\r
168 session_cache_limiter($old_session_cache_limiter);
\r
170 if (isset($_OLD_SESSION)) {
\r
171 $_SESSION = $_OLD_SESSION;
\r
172 unset($_OLD_SESSION);
\r
178 // in SSH2 a shared secret and an exchange hash are generated through the key exchange process.
\r
179 // the IV client to server is the hash of that "nonce" with the letter A and for the encryption key it's the letter C.
\r
180 // if the hash doesn't produce enough a key or an IV that's long enough concat successive hashes of the
\r
181 // original hash and the current hash. we'll be emulating that. for more info see the following URL:
\r
183 // http://tools.ietf.org/html/rfc4253#section-7.2
\r
185 // see the is_string($crypto) part for an example of how to expand the keys
\r
186 $key = pack('H*', sha1($seed . 'A'));
\r
187 $iv = pack('H*', sha1($seed . 'C'));
\r
189 // ciphers are used as per the nist.gov link below. also, see this link:
\r
191 // http://en.wikipedia.org/wiki/Cryptographically_secure_pseudorandom_number_generator#Designs_based_on_cryptographic_primitives
\r
193 case class_exists('Crypt_AES'):
\r
194 $crypto = new Crypt_AES(CRYPT_AES_MODE_CTR);
\r
196 case class_exists('Crypt_TripleDES'):
\r
197 $crypto = new Crypt_TripleDES(CRYPT_DES_MODE_CTR);
\r
199 case class_exists('Crypt_DES'):
\r
200 $crypto = new Crypt_DES(CRYPT_DES_MODE_CTR);
\r
202 case class_exists('Crypt_RC4'):
\r
203 $crypto = new Crypt_RC4();
\r
207 return crypt_random_string($length);
\r
210 $crypto->setKey($key);
\r
211 $crypto->setIV($iv);
\r
212 $crypto->enableContinuousBuffer();
\r
215 if (is_string($crypto)) {
\r
216 // the following is based off of ANSI X9.31:
\r
218 // http://csrc.nist.gov/groups/STM/cavp/documents/rng/931rngext.pdf
\r
220 // OpenSSL uses that same standard for it's random numbers:
\r
222 // http://www.opensource.apple.com/source/OpenSSL/OpenSSL-38/openssl/fips-1.0/rand/fips_rand.c
\r
223 // (do a search for "ANS X9.31 A.2.4")
\r
225 // ANSI X9.31 recommends ciphers be used and phpseclib does use them if they're available (see
\r
226 // later on in the code) but if they're not we'll use sha1
\r
228 while (strlen($result) < $length) { // each loop adds 20 bytes
\r
229 // microtime() isn't packed as "densely" as it could be but then neither is that the idea.
\r
230 // the idea is simply to ensure that each "block" has a unique element to it.
\r
231 $i = pack('H*', sha1(microtime()));
\r
232 $r = pack('H*', sha1($i ^ $v));
\r
233 $v = pack('H*', sha1($r ^ $i));
\r
236 return substr($result, 0, $length);
\r
239 //return $crypto->encrypt(str_repeat("\0", $length));
\r
242 while (strlen($result) < $length) {
\r
243 $i = $crypto->encrypt(microtime());
\r
244 $r = $crypto->encrypt($i ^ $v);
\r
245 $v = $crypto->encrypt($r ^ $i);
\r
248 return substr($result, 0, $length);
\r