| Index: trunk/phase3/includes/CryptRand.php |
| — | — | @@ -0,0 +1,252 @@ |
| | 2 | +<?php |
| | 3 | +/** |
| | 4 | + * A static cryptographic random generator class used for generating secret keys |
| | 5 | + * |
| | 6 | + * This is based in part on Drupal code as well as what we used in our own code |
| | 7 | + * prior to introduction of this class. |
| | 8 | + * |
| | 9 | + * @file |
| | 10 | + */ |
| | 11 | + |
| | 12 | +final class MWCryptRand { |
| | 13 | + |
| | 14 | + /** |
| | 15 | + * Initialize an initial random state based off of whatever we can find |
| | 16 | + */ |
| | 17 | + private static function initialRandomState() { |
| | 18 | + // $_SERVER contains a variety of unstable user and system specific information |
| | 19 | + // It'll vary a little with each page, and vary even more with separate users |
| | 20 | + // It'll also vary slightly across different machines |
| | 21 | + $state = serialize( $_SERVER ); |
| | 22 | + |
| | 23 | + // To try and vary the system information of the state a bit more |
| | 24 | + // by including the system's hostname into the state |
| | 25 | + $state .= wfHostname(); |
| | 26 | + |
| | 27 | + // Try and make this a little more unstable by including the varying process |
| | 28 | + // id of the php process we are running inside of if we are able to access it |
| | 29 | + if ( function_exists( 'getmypid' ) ) { |
| | 30 | + $state .= getmypid(); |
| | 31 | + } |
| | 32 | + |
| | 33 | + // If available try to increase the instability of the data by throwing in |
| | 34 | + // the precise amount of memory that we happen to be using at the moment. |
| | 35 | + if ( function_exists( 'memory_get_usage' ) ) { |
| | 36 | + $state .= memory_get_usage( true ); |
| | 37 | + } |
| | 38 | + |
| | 39 | + // It's mostly worthless but throw the wiki's id into the data for a little more variance |
| | 40 | + $state .= wfWikiID(); |
| | 41 | + |
| | 42 | + // If we have a secret key or proxy key set then throw it into the state as well |
| | 43 | + global $wgSecretKey, $wgProxyKey; |
| | 44 | + if ( $wgSecretKey ) { |
| | 45 | + $state .= $wgSecretKey; |
| | 46 | + } elseif ( $wgProxyKey ) { |
| | 47 | + $state .= $wgProxyKey; |
| | 48 | + } |
| | 49 | + |
| | 50 | + return $state; |
| | 51 | + } |
| | 52 | + |
| | 53 | + /** |
| | 54 | + * Return a rolling random state initially build using data from unstable sources |
| | 55 | + * @return A new weak random state |
| | 56 | + */ |
| | 57 | + public static function randomState() { |
| | 58 | + static $state = null; |
| | 59 | + if ( is_null( $state ) ) { |
| | 60 | + // Initialize the state with whatever unstable data we can find |
| | 61 | + // It's important that this data is hashed right afterwards to prevent |
| | 62 | + // it from being leaked into the output stream |
| | 63 | + $state = self::initialRandomState(); |
| | 64 | + } |
| | 65 | + // Generate a new random state based on the initial random state or previous |
| | 66 | + // random state by combining it with both the current time and a random value |
| | 67 | + // Simple append/prepend based methods of combining data and a salt have |
| | 68 | + // weaknesses in them, take advantage of the availability of hmac to abuse |
| | 69 | + // it's method of combining data and a key into a hash which is free of |
| | 70 | + // the typical weakness of simple concatenation |
| | 71 | + // Note that in hmac large keys are reduced in size and the key is then |
| | 72 | + // xor-ed to create two separate keys. For this reason we use the smaller |
| | 73 | + // time+rand as the key and the larger state as the data. |
| | 74 | + // We also don't bother passing numbers to mt_rand since you can't make |
| | 75 | + // it generate with any more entropy than it's default max value. |
| | 76 | + $state = self::hmac( $state, microtime() . mt_rand() ); |
| | 77 | + return $state; |
| | 78 | + } |
| | 79 | + |
| | 80 | + /** |
| | 81 | + * Decide on the best acceptable hash algorithm we have available for hash() |
| | 82 | + * @return String A hash algorithm |
| | 83 | + */ |
| | 84 | + private static function hashAlgo() { |
| | 85 | + static $algo = null; |
| | 86 | + if ( !is_null( $algo ) ) { |
| | 87 | + return $algo; |
| | 88 | + } |
| | 89 | + |
| | 90 | + $algos = hash_algos(); |
| | 91 | + $preference = array( 'whirlpool', 'sha256', 'sha1', 'md5' ); |
| | 92 | + |
| | 93 | + foreach ( $preference as $algorithm ) { |
| | 94 | + if ( in_array( $algorithm, $algos ) ) { |
| | 95 | + $algo = $algorithm; # assign to static |
| | 96 | + return $algo; |
| | 97 | + } |
| | 98 | + } |
| | 99 | + |
| | 100 | + // We only reach here if no acceptable hash is found in the list, this should |
| | 101 | + // be a technical impossibility since most of php's hash list is fixed and |
| | 102 | + // some of the ones we list are available as their own native functions |
| | 103 | + // But since we already require at least 5.2 and hash() was default in |
| | 104 | + // 5.1.2 we don't bother falling back to methods like sha1 and md5. |
| | 105 | + throw new MWException( "Could not find an acceptable hashing function in hash_algos()" ); |
| | 106 | + } |
| | 107 | + |
| | 108 | + /** |
| | 109 | + * Generate an acceptably unstable one-way-hash of some text |
| | 110 | + * making use of the best hash algorithm that we have available. |
| | 111 | + * |
| | 112 | + * @return String A raw hash of the data |
| | 113 | + */ |
| | 114 | + private static function hash( $data ) { |
| | 115 | + return hash( self::hashAlgo(), $data, true ); |
| | 116 | + } |
| | 117 | + |
| | 118 | + /** |
| | 119 | + * Generate an acceptably unstable one-way-hmac of some text |
| | 120 | + * making use of the best hash algorithm that we have available. |
| | 121 | + * |
| | 122 | + * @return String A raw hash of the data |
| | 123 | + */ |
| | 124 | + private static function hmac( $data, $key ) { |
| | 125 | + return hash_hmac( self::hashAlgo(), $data, $key, true ); |
| | 126 | + } |
| | 127 | + |
| | 128 | + |
| | 129 | + |
| | 130 | + private static $strong = null; |
| | 131 | + |
| | 132 | + /** |
| | 133 | + * Return a boolean indicating whether or not the source used for cryptographic |
| | 134 | + * random bytes generation in the previously run generate* call |
| | 135 | + * was cryptographically strong. |
| | 136 | + * |
| | 137 | + * @return bool Returns true if the source was strong, false if not. |
| | 138 | + */ |
| | 139 | + public static function wasStrong() { |
| | 140 | + if ( is_null( self::$strong ) ) { |
| | 141 | + throw new MWException( __METHOD__ . ' called before generation of random data' ); |
| | 142 | + } |
| | 143 | + return self::$strong; |
| | 144 | + } |
| | 145 | + |
| | 146 | + /** |
| | 147 | + * Generate a run of (ideally) cryptographically random data and return |
| | 148 | + * it in raw binary form. |
| | 149 | + * You can use MWCryptRand::wasStrong() if you wish to know if the source used |
| | 150 | + * was cryptographically strong. |
| | 151 | + * |
| | 152 | + * @param $bytes int the number of bytes of random data to generate |
| | 153 | + * @return String Raw binary random data |
| | 154 | + */ |
| | 155 | + public static function generate( $bytes ) { |
| | 156 | + $bytes = floor( $bytes ); |
| | 157 | + static $buffer = ''; |
| | 158 | + if ( is_null( self::$strong ) ) { |
| | 159 | + // Set strength to false initially until we know what source data is coming from |
| | 160 | + self::$strong = true; |
| | 161 | + } |
| | 162 | + |
| | 163 | + if ( strlen( $buffer ) < $bytes ) { |
| | 164 | + // /dev/urandom is generally considered the best possible commonly |
| | 165 | + // available random source, and is available on most *nix systems. |
| | 166 | + wfSuppressWarnings(); |
| | 167 | + $urandom = fopen( "/dev/urandom", "rb" ); |
| | 168 | + wfRestoreWarnings(); |
| | 169 | + |
| | 170 | + // Attempt to read all our random data from urandom |
| | 171 | + // php's fread always does buffered reads based on the stream's chunk_size |
| | 172 | + // so in reality it will usually read more than the amount of data we're |
| | 173 | + // asked for and it doesn't cost anything extra to store that. |
| | 174 | + // We don't have access to the stream's chunk_size, fread maxes out at 8k |
| | 175 | + // so we'll go along with Drupal's decision to read at least 4k |
| | 176 | + if ( $urandom ) { |
| | 177 | + $buffer .= fread( $urandom, max( 1024 * 4, $bytes ) ); |
| | 178 | + fclose( $urandom ); |
| | 179 | + if ( strlen( $buffer ) >= $bytes ) { |
| | 180 | + // urandom is always strong, set to true if all our data was generated using it |
| | 181 | + self::$strong = true; |
| | 182 | + } |
| | 183 | + } |
| | 184 | + } |
| | 185 | + |
| | 186 | + if ( strlen( $buffer ) < $bytes ) { |
| | 187 | + // If available and we failed to read enough data out of urandom make use |
| | 188 | + // of openssl's random_pesudo_bytes method to attempt to generate randomness. |
| | 189 | + // However don't do this on Windows with PHP < 5.3.4 due to a bug: |
| | 190 | + // http://stackoverflow.com/questions/1940168/openssl-random-pseudo-bytes-is-slow-php |
| | 191 | + if ( ( $bytes - strlen( $buffer ) > 0 ) |
| | 192 | + && function_exists( 'openssl_random_pseudo_bytes' ) |
| | 193 | + && ( !wfIsWindows() || version_compare( PHP_VERSION, '5.3.4', '>=' ) ) |
| | 194 | + ) { |
| | 195 | + $buffer .= openssl_random_pseudo_bytes( $bytes - strlen( $buffer ), $openssl_strong ); |
| | 196 | + if ( strlen( $buffer ) >= $bytes ) { |
| | 197 | + // openssl tells us if the random source was strong, if some of our data was generated |
| | 198 | + // using it use it's say on whether the randomness is strong |
| | 199 | + self::$strong = !!$openssl_strong; |
| | 200 | + } |
| | 201 | + } |
| | 202 | + } |
| | 203 | + |
| | 204 | + |
| | 205 | + // If we cannot use or generate enough data from /dev/urandom or openssl |
| | 206 | + // use this loop to generate a good set of pesudo random data. |
| | 207 | + // This works by initializing a random state using a pile of unstable data |
| | 208 | + // and continually shoving it through a hash along with a variable salt. |
| | 209 | + // We hash the random state with more salt to avoid the state from leaking |
| | 210 | + // out and being used to predict the /randomness/ that follows. |
| | 211 | + while ( strlen( $buffer ) < $bytes ) { |
| | 212 | + $buffer .= self::hmac( self::randomState(), mt_rand() ); |
| | 213 | + // This code is never really cryptographically strong, if we use it |
| | 214 | + // at all, then set strong to false. |
| | 215 | + self::$strong = false; |
| | 216 | + } |
| | 217 | + |
| | 218 | + // Once the buffer has been filled up with enough random data to fulfill |
| | 219 | + // the request shift off enough data to handle the request and leave the |
| | 220 | + // unused portion left inside the buffer for the next request for random data |
| | 221 | + $generated = substr( $buffer, 0, $bytes ); |
| | 222 | + $buffer = substr( $buffer, $bytes ); |
| | 223 | + |
| | 224 | + return $generated; |
| | 225 | + } |
| | 226 | + |
| | 227 | + /** |
| | 228 | + * Generate a run of (ideally) cryptographically random data and return |
| | 229 | + * it in hexadecimal string format. |
| | 230 | + * You can use MWCryptRand::wasStrong() if you wish to know if the source used |
| | 231 | + * was cryptographically strong. |
| | 232 | + * |
| | 233 | + * @param $chars int the number of hex chars of random data to generate |
| | 234 | + * @return String Hexadecimal random data |
| | 235 | + */ |
| | 236 | + public static function generateHex( $chars ) { |
| | 237 | + // hex strings are 2x the length of raw binary so we divide the length in half |
| | 238 | + // odd numbers will result in a .5 that leads the generate() being 1 character |
| | 239 | + // short, so we use ceil() to ensure that we always have enough bytes |
| | 240 | + $bytes = ceil( $chars / 2 ); |
| | 241 | + // Generate the data and then convert it to a hex string |
| | 242 | + $hex = bin2hex( self::generate( $bytes ) ); |
| | 243 | + // A bit of paranoia here, the caller asked for a specific length of string |
| | 244 | + // here, and it's possible (eg when given an odd number) that we may actually |
| | 245 | + // have at least 1 char more than they asked for. Just in case they made this |
| | 246 | + // call intending to insert it into a database that does truncation we don't |
| | 247 | + // want to give them too much and end up with their database and their live |
| | 248 | + // code having two different values because part of what we gave them is truncated |
| | 249 | + // hence, we strip out any run of characters longer than what we were asked for. |
| | 250 | + return substr( $hex, 0, $chars ); |
| | 251 | + } |
| | 252 | + |
| | 253 | +} |
| Index: trunk/phase3/includes/AutoLoader.php |
| — | — | @@ -49,6 +49,7 @@ |
| 50 | 50 | 'ConfEditorToken' => 'includes/ConfEditor.php', |
| 51 | 51 | 'Cookie' => 'includes/Cookie.php', |
| 52 | 52 | 'CookieJar' => 'includes/Cookie.php', |
| | 53 | + 'MWCryptRand' => 'includes/CryptRand.php', |
| 53 | 54 | 'CurlHttpRequest' => 'includes/HttpFunctions.php', |
| 54 | 55 | // 'DBDataObject' => 'includes/DBDataObject.php', |
| 55 | 56 | // 'DBTable' => 'includes/DBTable.php', |