+++ /dev/null
-<?php
-/**
- * A static cryptographic random generator class used for generating secret keys
- *
- * This is based in part on Drupal code as well as what we used in our own code
- * prior to introduction of this class.
- *
- * @file
- */
-
-final class MWCryptRand {
-
- /**
- * Initialize an initial random state based off of whatever we can find
- */
- private static function initialRandomState() {
- // $_SERVER contains a variety of unstable user and system specific information
- // It'll vary a little with each page, and vary even more with separate users
- // It'll also vary slightly across different machines
- $state = serialize( $_SERVER );
-
- // To try and vary the system information of the state a bit more
- // by including the system's hostname into the state
- $state .= wfHostname();
-
- // Try and make this a little more unstable by including the varying process
- // id of the php process we are running inside of if we are able to access it
- if ( function_exists( 'getmypid' ) ) {
- $state .= getmypid();
- }
-
- // If available try to increase the instability of the data by throwing in
- // the precise amount of memory that we happen to be using at the moment.
- if ( function_exists( 'memory_get_usage' ) ) {
- $state .= memory_get_usage( true );
- }
-
- // It's mostly worthless but throw the wiki's id into the data for a little more variance
- $state .= wfWikiID();
-
- // If we have a secret key or proxy key set then throw it into the state as well
- global $wgSecretKey, $wgProxyKey;
- if ( $wgSecretKey ) {
- $state .= $wgSecretKey;
- } elseif ( $wgProxyKey ) {
- $state .= $wgProxyKey;
- }
-
- return $state;
- }
-
- /**
- * Return a rolling random state initially build using data from unstable sources
- * @return A new weak random state
- */
- public static function randomState() {
- static $state = null;
- if ( is_null( $state ) ) {
- // Initialize the state with whatever unstable data we can find
- // It's important that this data is hashed right afterwards to prevent
- // it from being leaked into the output stream
- $state = self::initialRandomState();
- }
- // Generate a new random state based on the initial random state or previous
- // random state by combining it with both the current time and a random value
- // Simple append/prepend based methods of combining data and a salt have
- // weaknesses in them, take advantage of the availability of hmac to abuse
- // it's method of combining data and a key into a hash which is free of
- // the typical weakness of simple concatenation
- // Note that in hmac large keys are reduced in size and the key is then
- // xor-ed to create two separate keys. For this reason we use the smaller
- // time+rand as the key and the larger state as the data.
- // We also don't bother passing numbers to mt_rand since you can't make
- // it generate with any more entropy than it's default max value.
- $state = self::hmac( $state, microtime() . mt_rand() );
- return $state;
- }
-
- /**
- * Decide on the best acceptable hash algorithm we have available for hash()
- * @return String A hash algorithm
- */
- private static function hashAlgo() {
- static $algo = null;
- if ( !is_null( $algo ) ) {
- return $algo;
- }
-
- $algos = hash_algos();
- $preference = array( 'whirlpool', 'sha256', 'sha1', 'md5' );
-
- foreach ( $preference as $algorithm ) {
- if ( in_array( $algorithm, $algos ) ) {
- $algo = $algorithm; # assign to static
- return $algo;
- }
- }
-
- // We only reach here if no acceptable hash is found in the list, this should
- // be a technical impossibility since most of php's hash list is fixed and
- // some of the ones we list are available as their own native functions
- // But since we already require at least 5.2 and hash() was default in
- // 5.1.2 we don't bother falling back to methods like sha1 and md5.
- throw new MWException( "Could not find an acceptable hashing function in hash_algos()" );
- }
-
- /**
- * Generate an acceptably unstable one-way-hash of some text
- * making use of the best hash algorithm that we have available.
- *
- * @return String A raw hash of the data
- */
- private static function hash( $data ) {
- return hash( self::hashAlgo(), $data, true );
- }
-
- /**
- * Generate an acceptably unstable one-way-hmac of some text
- * making use of the best hash algorithm that we have available.
- *
- * @return String A raw hash of the data
- */
- private static function hmac( $data, $key ) {
- return hash_hmac( self::hashAlgo(), $data, $key, true );
- }
-
-
-
- private static $strong = null;
-
- /**
- * Return a boolean indicating whether or not the source used for cryptographic
- * random bytes generation in the previously run generate* call
- * was cryptographically strong.
- *
- * @return bool Returns true if the source was strong, false if not.
- */
- public static function wasStrong() {
- if ( is_null( self::$strong ) ) {
- throw new MWException( __METHOD__ . ' called before generation of random data' );
- }
- return self::$strong;
- }
-
- /**
- * Generate a run of (ideally) cryptographically random data and return
- * it in raw binary form.
- * You can use MWCryptRand::wasStrong() if you wish to know if the source used
- * was cryptographically strong.
- *
- * @param $bytes int the number of bytes of random data to generate
- * @return String Raw binary random data
- */
- public static function generate( $bytes ) {
- $bytes = floor( $bytes );
- static $buffer = '';
- if ( is_null( self::$strong ) ) {
- // Set strength to false initially until we know what source data is coming from
- self::$strong = true;
- }
-
- if ( strlen( $buffer ) < $bytes ) {
- // /dev/urandom is generally considered the best possible commonly
- // available random source, and is available on most *nix systems.
- wfSuppressWarnings();
- $urandom = fopen( "/dev/urandom", "rb" );
- wfRestoreWarnings();
-
- // Attempt to read all our random data from urandom
- // php's fread always does buffered reads based on the stream's chunk_size
- // so in reality it will usually read more than the amount of data we're
- // asked for and it doesn't cost anything extra to store that.
- // We don't have access to the stream's chunk_size, fread maxes out at 8k
- // so we'll go along with Drupal's decision to read at least 4k
- if ( $urandom ) {
- $buffer .= fread( $urandom, max( 1024 * 4, $bytes ) );
- fclose( $urandom );
- if ( strlen( $buffer ) >= $bytes ) {
- // urandom is always strong, set to true if all our data was generated using it
- self::$strong = true;
- }
- }
- }
-
- if ( strlen( $buffer ) < $bytes ) {
- // If available and we failed to read enough data out of urandom make use
- // of openssl's random_pesudo_bytes method to attempt to generate randomness.
- // However don't do this on Windows with PHP < 5.3.4 due to a bug:
- // http://stackoverflow.com/questions/1940168/openssl-random-pseudo-bytes-is-slow-php
- if ( ( $bytes - strlen( $buffer ) > 0 )
- && function_exists( 'openssl_random_pseudo_bytes' )
- && ( !wfIsWindows() || version_compare( PHP_VERSION, '5.3.4', '>=' ) )
- ) {
- $buffer .= openssl_random_pseudo_bytes( $bytes - strlen( $buffer ), $openssl_strong );
- if ( strlen( $buffer ) >= $bytes ) {
- // openssl tells us if the random source was strong, if some of our data was generated
- // using it use it's say on whether the randomness is strong
- self::$strong = !!$openssl_strong;
- }
- }
- }
-
-
- // If we cannot use or generate enough data from /dev/urandom or openssl
- // use this loop to generate a good set of pesudo random data.
- // This works by initializing a random state using a pile of unstable data
- // and continually shoving it through a hash along with a variable salt.
- // We hash the random state with more salt to avoid the state from leaking
- // out and being used to predict the /randomness/ that follows.
- while ( strlen( $buffer ) < $bytes ) {
- $buffer .= self::hmac( self::randomState(), mt_rand() );
- // This code is never really cryptographically strong, if we use it
- // at all, then set strong to false.
- self::$strong = false;
- }
-
- // Once the buffer has been filled up with enough random data to fulfill
- // the request shift off enough data to handle the request and leave the
- // unused portion left inside the buffer for the next request for random data
- $generated = substr( $buffer, 0, $bytes );
- $buffer = substr( $buffer, $bytes );
-
- return $generated;
- }
-
- /**
- * Generate a run of (ideally) cryptographically random data and return
- * it in hexadecimal string format.
- * You can use MWCryptRand::wasStrong() if you wish to know if the source used
- * was cryptographically strong.
- *
- * @param $chars int the number of hex chars of random data to generate
- * @return String Hexadecimal random data
- */
- public static function generateHex( $chars ) {
- // hex strings are 2x the length of raw binary so we divide the length in half
- // odd numbers will result in a .5 that leads the generate() being 1 character
- // short, so we use ceil() to ensure that we always have enough bytes
- $bytes = ceil( $chars / 2 );
- // Generate the data and then convert it to a hex string
- $hex = bin2hex( self::generate( $bytes ) );
- // A bit of paranoia here, the caller asked for a specific length of string
- // here, and it's possible (eg when given an odd number) that we may actually
- // have at least 1 char more than they asked for. Just in case they made this
- // call intending to insert it into a database that does truncation we don't
- // want to give them too much and end up with their database and their live
- // code having two different values because part of what we gave them is truncated
- // hence, we strip out any run of characters longer than what we were asked for.
- return substr( $hex, 0, $chars );
- }
-
-}
dépôts / lhc / web / wiklou.git / commitdiff