From: Aaron Schulz <aschulz@wikimedia.org>
Date: Mon, 22 Apr 2013 06:57:37 +0000 (-0700)
Subject: Moved CryptRand.php to MWCryptRand.php
X-Git-Tag: 1.31.0-rc.0~19903
X-Git-Url: https://git.cyclocoop.org/%7B%24www_url%7Dadmin/membres/message.php?a=commitdiff_plain;h=b41a2f8f68acff2c4fa61ea8a7d226709a61753f;p=lhc%2Fweb%2Fwiklou.git

Moved CryptRand.php to MWCryptRand.php

Change-Id: I03e3742f270ccf05ea923a46e8f8171e6f73ffcd
---

diff --git a/includes/AutoLoader.php b/includes/AutoLoader.php
index 8c20c8ab71..b9328d028e 100644
--- a/includes/AutoLoader.php
+++ b/includes/AutoLoader.php
@@ -65,7 +65,7 @@ $wgAutoloadLocalClasses = array(
 	'ConfEditorToken' => 'includes/ConfEditor.php',
 	'Cookie' => 'includes/Cookie.php',
 	'CookieJar' => 'includes/Cookie.php',
-	'MWCryptRand' => 'includes/CryptRand.php',
+	'MWCryptRand' => 'includes/MWCryptRand.php',
 	'CurlHttpRequest' => 'includes/HttpFunctions.php',
 	'DeferrableUpdate' => 'includes/DeferredUpdates.php',
 	'DeferredUpdates' => 'includes/DeferredUpdates.php',
diff --git a/includes/CryptRand.php b/includes/CryptRand.php
deleted file mode 100644
index bac018e896..0000000000
--- a/includes/CryptRand.php
+++ /dev/null
@@ -1,497 +0,0 @@
-<?php
-/**
- * A 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.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- * http://www.gnu.org/copyleft/gpl.html
- *
- * @author Daniel Friesen
- * @file
- */
-
-class MWCryptRand {
-
-	/**
-	 * Minimum number of iterations we want to make in our drift calculations.
-	 */
-	const MIN_ITERATIONS = 1000;
-
-	/**
-	 * Number of milliseconds we want to spend generating each separate byte
-	 * of the final generated bytes.
-	 * This is used in combination with the hash length to determine the duration
-	 * we should spend doing drift calculations.
-	 */
-	const MSEC_PER_BYTE = 0.5;
-
-	/**
-	 * Singleton instance for public use
-	 */
-	protected static $singleton = null;
-
-	/**
-	 * The hash algorithm being used
-	 */
-	protected $algo = null;
-
-	/**
-	 * The number of bytes outputted by the hash algorithm
-	 */
-	protected $hashLength = null;
-
-	/**
-	 * A boolean indicating whether the previous random generation was done using
-	 * cryptographically strong random number generator or not.
-	 */
-	protected $strong = null;
-
-	/**
-	 * Initialize an initial random state based off of whatever we can find
-	 */
-	protected 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 vary the system information of the state a bit more
-		// by including the system's hostname into the state
-		$state .= wfHostname();
-
-		// Try to gather a little entropy from the different php rand sources
-		$state .= rand() . uniqid( mt_rand(), true );
-
-		// Include some information about the filesystem's current state in the random state
-		$files = array();
-
-		// We know this file is here so grab some info about ourselves
-		$files[] = __FILE__;
-
-		// We must also have a parent folder, and with the usual file structure, a grandparent
-		$files[] = __DIR__;
-		$files[] = dirname( __DIR__ );
-
-		// The config file is likely the most often edited file we know should be around
-		// so include its stat info into the state.
-		// The constant with its location will almost always be defined, as WebStart.php defines
-		// MW_CONFIG_FILE to $IP/LocalSettings.php unless being configured with MW_CONFIG_CALLBACK (eg. the installer)
-		if ( defined( 'MW_CONFIG_FILE' ) ) {
-			$files[] = MW_CONFIG_FILE;
-		}
-
-		foreach ( $files as $file ) {
-			wfSuppressWarnings();
-			$stat = stat( $file );
-			wfRestoreWarnings();
-			if ( $stat ) {
-				// stat() duplicates data into numeric and string keys so kill off all the numeric ones
-				foreach ( $stat as $k => $v ) {
-					if ( is_numeric( $k ) ) {
-						unset( $k );
-					}
-				}
-				// The absolute filename itself will differ from install to install so don't leave it out
-				if ( ( $path = realpath( $file ) ) !== false ) {
-					$state .= $path;
-				} else {
-					$state .= $file;
-				}
-				$state .= implode( '', $stat );
-			} else {
-				// The fact that the file isn't there is worth at least a
-				// minuscule amount of entropy.
-				$state .= '0';
-			}
-		}
-
-		// 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;
-	}
-
-	/**
-	 * Randomly hash data while mixing in clock drift data for randomness
-	 *
-	 * @param string $data The data to randomly hash.
-	 * @return String The hashed bytes
-	 * @author Tim Starling
-	 */
-	protected function driftHash( $data ) {
-		// Minimum number of iterations (to avoid slow operations causing the loop to gather little entropy)
-		$minIterations = self::MIN_ITERATIONS;
-		// Duration of time to spend doing calculations (in seconds)
-		$duration = ( self::MSEC_PER_BYTE / 1000 ) * $this->hashLength();
-		// Create a buffer to use to trigger memory operations
-		$bufLength = 10000000;
-		$buffer = str_repeat( ' ', $bufLength );
-		$bufPos = 0;
-
-		// Iterate for $duration seconds or at least $minIterations number of iterations
-		$iterations = 0;
-		$startTime = microtime( true );
-		$currentTime = $startTime;
-		while ( $iterations < $minIterations || $currentTime - $startTime < $duration ) {
-			// Trigger some memory writing to trigger some bus activity
-			// This may create variance in the time between iterations
-			$bufPos = ( $bufPos + 13 ) % $bufLength;
-			$buffer[$bufPos] = ' ';
-			// Add the drift between this iteration and the last in as entropy
-			$nextTime = microtime( true );
-			$delta = (int)( ( $nextTime - $currentTime ) * 1000000 );
-			$data .= $delta;
-			// Every 100 iterations hash the data and entropy
-			if ( $iterations % 100 === 0 ) {
-				$data = sha1( $data );
-			}
-			$currentTime = $nextTime;
-			$iterations++;
-		}
-		$timeTaken = $currentTime - $startTime;
-		$data = $this->hash( $data );
-
-		wfDebug( __METHOD__ . ": Clock drift calculation " .
-			"(time-taken=" . ( $timeTaken * 1000 ) . "ms, " .
-			"iterations=$iterations, " .
-			"time-per-iteration=" . ( $timeTaken / $iterations * 1e6 ) . "us)\n" );
-		return $data;
-	}
-
-	/**
-	 * Return a rolling random state initially build using data from unstable sources
-	 * @return string A new weak random state
-	 */
-	protected 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 = $this->hash( $this->initialRandomState() );
-		}
-		// Generate a new random state based on the initial random state or previous
-		// random state by combining it with clock drift
-		$state = $this->driftHash( $state );
-		return $state;
-	}
-
-	/**
-	 * Decide on the best acceptable hash algorithm we have available for hash()
-	 * @throws MWException
-	 * @return String A hash algorithm
-	 */
-	protected function hashAlgo() {
-		if ( !is_null( $this->algo ) ) {
-			return $this->algo;
-		}
-
-		$algos = hash_algos();
-		$preference = array( 'whirlpool', 'sha256', 'sha1', 'md5' );
-
-		foreach ( $preference as $algorithm ) {
-			if ( in_array( $algorithm, $algos ) ) {
-				$this->algo = $algorithm;
-				wfDebug( __METHOD__ . ": Using the {$this->algo} hash algorithm.\n" );
-				return $this->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()" );
-	}
-
-	/**
-	 * Return the byte-length output of the hash algorithm we are
-	 * using in self::hash and self::hmac.
-	 *
-	 * @return int Number of bytes the hash outputs
-	 */
-	protected function hashLength() {
-		if ( is_null( $this->hashLength ) ) {
-			$this->hashLength = strlen( $this->hash( '' ) );
-		}
-		return $this->hashLength;
-	}
-
-	/**
-	 * Generate an acceptably unstable one-way-hash of some text
-	 * making use of the best hash algorithm that we have available.
-	 *
-	 * @param $data string
-	 * @return String A raw hash of the data
-	 */
-	protected function hash( $data ) {
-		return hash( $this->hashAlgo(), $data, true );
-	}
-
-	/**
-	 * Generate an acceptably unstable one-way-hmac of some text
-	 * making use of the best hash algorithm that we have available.
-	 *
-	 * @param $data string
-	 * @param $key string
-	 * @return String A raw hash of the data
-	 */
-	protected function hmac( $data, $key ) {
-		return hash_hmac( $this->hashAlgo(), $data, $key, true );
-	}
-
-	/**
-	 * @see self::wasStrong()
-	 */
-	public function realWasStrong() {
-		if ( is_null( $this->strong ) ) {
-			throw new MWException( __METHOD__ . ' called before generation of random data' );
-		}
-		return $this->strong;
-	}
-
-	/**
-	 * @see self::generate()
-	 */
-	public function realGenerate( $bytes, $forceStrong = false ) {
-		wfProfileIn( __METHOD__ );
-
-		wfDebug( __METHOD__ . ": Generating cryptographic random bytes for " . wfGetAllCallers( 5 ) . "\n" );
-
-		$bytes = floor( $bytes );
-		static $buffer = '';
-		if ( is_null( $this->strong ) ) {
-			// Set strength to false initially until we know what source data is coming from
-			$this->strong = true;
-		}
-
-		if ( strlen( $buffer ) < $bytes ) {
-			// If available make use of mcrypt_create_iv URANDOM source to generate randomness
-			// On unix-like systems this reads from /dev/urandom but does it without any buffering
-			// and bypasses openbasedir restrictions, so it's preferable to reading directly
-			// On Windows starting in PHP 5.3.0 Windows' native CryptGenRandom is used to generate
-			// entropy so this is also preferable to just trying to read urandom because it may work
-			// on Windows systems as well.
-			if ( function_exists( 'mcrypt_create_iv' ) ) {
-				wfProfileIn( __METHOD__ . '-mcrypt' );
-				$rem = $bytes - strlen( $buffer );
-				$iv = mcrypt_create_iv( $rem, MCRYPT_DEV_URANDOM );
-				if ( $iv === false ) {
-					wfDebug( __METHOD__ . ": mcrypt_create_iv returned false.\n" );
-				} else {
-					$buffer .= $iv;
-					wfDebug( __METHOD__ . ": mcrypt_create_iv generated " . strlen( $iv ) . " bytes of randomness.\n" );
-				}
-				wfProfileOut( __METHOD__ . '-mcrypt' );
-			}
-		}
-
-		if ( strlen( $buffer ) < $bytes ) {
-			// If available make use of openssl's random_pseudo_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
-			// http://git.php.net/?p=php-src.git;a=commitdiff;h=cd62a70863c261b07f6dadedad9464f7e213cad5
-			if ( function_exists( 'openssl_random_pseudo_bytes' )
-				&& ( !wfIsWindows() || version_compare( PHP_VERSION, '5.3.4', '>=' ) )
-			) {
-				wfProfileIn( __METHOD__ . '-openssl' );
-				$rem = $bytes - strlen( $buffer );
-				$openssl_bytes = openssl_random_pseudo_bytes( $rem, $openssl_strong );
-				if ( $openssl_bytes === false ) {
-					wfDebug( __METHOD__ . ": openssl_random_pseudo_bytes returned false.\n" );
-				} else {
-					$buffer .= $openssl_bytes;
-					wfDebug( __METHOD__ . ": openssl_random_pseudo_bytes generated " . strlen( $openssl_bytes ) . " bytes of " . ( $openssl_strong ? "strong" : "weak" ) . " randomness.\n" );
-				}
-				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
-					$this->strong = !!$openssl_strong;
-				}
-				wfProfileOut( __METHOD__ . '-openssl' );
-			}
-		}
-
-		// Only read from urandom if we can control the buffer size or were passed forceStrong
-		if ( strlen( $buffer ) < $bytes && ( function_exists( 'stream_set_read_buffer' ) || $forceStrong ) ) {
-			wfProfileIn( __METHOD__ . '-fopen-urandom' );
-			$rem = $bytes - strlen( $buffer );
-			if ( !function_exists( 'stream_set_read_buffer' ) && $forceStrong ) {
-				wfDebug( __METHOD__ . ": Was forced to read from /dev/urandom without control over the buffer size.\n" );
-			}
-			// /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 not storing that risks depleting the system's random pool.
-			// If stream_set_read_buffer is available set the chunk_size to the amount
-			// of data we need. Otherwise read 8k, php's default chunk_size.
-			if ( $urandom ) {
-				// php's default chunk_size is 8k
-				$chunk_size = 1024 * 8;
-				if ( function_exists( 'stream_set_read_buffer' ) ) {
-					// If possible set the chunk_size to the amount of data we need
-					stream_set_read_buffer( $urandom, $rem );
-					$chunk_size = $rem;
-				}
-				$random_bytes = fread( $urandom, max( $chunk_size, $rem ) );
-				$buffer .= $random_bytes;
-				fclose( $urandom );
-				wfDebug( __METHOD__ . ": /dev/urandom generated " . strlen( $random_bytes ) . " bytes of randomness.\n" );
-				if ( strlen( $buffer ) >= $bytes ) {
-					// urandom is always strong, set to true if all our data was generated using it
-					$this->strong = true;
-				}
-			} else {
-				wfDebug( __METHOD__ . ": /dev/urandom could not be opened.\n" );
-			}
-			wfProfileOut( __METHOD__ . '-fopen-urandom' );
-		}
-
-		// If we cannot use or generate enough data from a secure source
-		// use this loop to generate a good set of pseudo 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.
-		if ( strlen( $buffer ) < $bytes ) {
-			wfDebug( __METHOD__ . ": Falling back to using a pseudo random state to generate randomness.\n" );
-		}
-		while ( strlen( $buffer ) < $bytes ) {
-			wfProfileIn( __METHOD__ . '-fallback' );
-			$buffer .= $this->hmac( $this->randomState(), mt_rand() );
-			// This code is never really cryptographically strong, if we use it
-			// at all, then set strong to false.
-			$this->strong = false;
-			wfProfileOut( __METHOD__ . '-fallback' );
-		}
-
-		// 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 );
-
-		wfDebug( __METHOD__ . ": " . strlen( $buffer ) . " bytes of randomness leftover in the buffer.\n" );
-
-		wfProfileOut( __METHOD__ );
-		return $generated;
-	}
-
-	/**
-	 * @see self::generateHex()
-	 */
-	public function realGenerateHex( $chars, $forceStrong = false ) {
-		// 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( $this->generate( $bytes, $forceStrong ) );
-		// 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, $chars );
-	}
-
-	/** Publicly exposed static methods **/
-
-	/**
-	 * Return a singleton instance of MWCryptRand
-	 * @return MWCryptRand
-	 */
-	protected static function singleton() {
-		if ( is_null( self::$singleton ) ) {
-			self::$singleton = new self;
-		}
-		return self::$singleton;
-	}
-
-	/**
-	 * 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() {
-		return self::singleton()->realWasStrong();
-	}
-
-	/**
-	 * 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 int $bytes the number of bytes of random data to generate
-	 * @param bool $forceStrong Pass true if you want generate to prefer cryptographically
-	 *                          strong sources of entropy even if reading from them may steal
-	 *                          more entropy from the system than optimal.
-	 * @return String Raw binary random data
-	 */
-	public static function generate( $bytes, $forceStrong = false ) {
-		return self::singleton()->realGenerate( $bytes, $forceStrong );
-	}
-
-	/**
-	 * 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 int $chars the number of hex chars of random data to generate
-	 * @param bool $forceStrong Pass true if you want generate to prefer cryptographically
-	 *                          strong sources of entropy even if reading from them may steal
-	 *                          more entropy from the system than optimal.
-	 * @return String Hexadecimal random data
-	 */
-	public static function generateHex( $chars, $forceStrong = false ) {
-		return self::singleton()->realGenerateHex( $chars, $forceStrong );
-	}
-
-}
diff --git a/includes/MWCryptRand.php b/includes/MWCryptRand.php
new file mode 100644
index 0000000000..bac018e896
--- /dev/null
+++ b/includes/MWCryptRand.php
@@ -0,0 +1,497 @@
+<?php
+/**
+ * A 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.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @author Daniel Friesen
+ * @file
+ */
+
+class MWCryptRand {
+
+	/**
+	 * Minimum number of iterations we want to make in our drift calculations.
+	 */
+	const MIN_ITERATIONS = 1000;
+
+	/**
+	 * Number of milliseconds we want to spend generating each separate byte
+	 * of the final generated bytes.
+	 * This is used in combination with the hash length to determine the duration
+	 * we should spend doing drift calculations.
+	 */
+	const MSEC_PER_BYTE = 0.5;
+
+	/**
+	 * Singleton instance for public use
+	 */
+	protected static $singleton = null;
+
+	/**
+	 * The hash algorithm being used
+	 */
+	protected $algo = null;
+
+	/**
+	 * The number of bytes outputted by the hash algorithm
+	 */
+	protected $hashLength = null;
+
+	/**
+	 * A boolean indicating whether the previous random generation was done using
+	 * cryptographically strong random number generator or not.
+	 */
+	protected $strong = null;
+
+	/**
+	 * Initialize an initial random state based off of whatever we can find
+	 */
+	protected 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 vary the system information of the state a bit more
+		// by including the system's hostname into the state
+		$state .= wfHostname();
+
+		// Try to gather a little entropy from the different php rand sources
+		$state .= rand() . uniqid( mt_rand(), true );
+
+		// Include some information about the filesystem's current state in the random state
+		$files = array();
+
+		// We know this file is here so grab some info about ourselves
+		$files[] = __FILE__;
+
+		// We must also have a parent folder, and with the usual file structure, a grandparent
+		$files[] = __DIR__;
+		$files[] = dirname( __DIR__ );
+
+		// The config file is likely the most often edited file we know should be around
+		// so include its stat info into the state.
+		// The constant with its location will almost always be defined, as WebStart.php defines
+		// MW_CONFIG_FILE to $IP/LocalSettings.php unless being configured with MW_CONFIG_CALLBACK (eg. the installer)
+		if ( defined( 'MW_CONFIG_FILE' ) ) {
+			$files[] = MW_CONFIG_FILE;
+		}
+
+		foreach ( $files as $file ) {
+			wfSuppressWarnings();
+			$stat = stat( $file );
+			wfRestoreWarnings();
+			if ( $stat ) {
+				// stat() duplicates data into numeric and string keys so kill off all the numeric ones
+				foreach ( $stat as $k => $v ) {
+					if ( is_numeric( $k ) ) {
+						unset( $k );
+					}
+				}
+				// The absolute filename itself will differ from install to install so don't leave it out
+				if ( ( $path = realpath( $file ) ) !== false ) {
+					$state .= $path;
+				} else {
+					$state .= $file;
+				}
+				$state .= implode( '', $stat );
+			} else {
+				// The fact that the file isn't there is worth at least a
+				// minuscule amount of entropy.
+				$state .= '0';
+			}
+		}
+
+		// 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;
+	}
+
+	/**
+	 * Randomly hash data while mixing in clock drift data for randomness
+	 *
+	 * @param string $data The data to randomly hash.
+	 * @return String The hashed bytes
+	 * @author Tim Starling
+	 */
+	protected function driftHash( $data ) {
+		// Minimum number of iterations (to avoid slow operations causing the loop to gather little entropy)
+		$minIterations = self::MIN_ITERATIONS;
+		// Duration of time to spend doing calculations (in seconds)
+		$duration = ( self::MSEC_PER_BYTE / 1000 ) * $this->hashLength();
+		// Create a buffer to use to trigger memory operations
+		$bufLength = 10000000;
+		$buffer = str_repeat( ' ', $bufLength );
+		$bufPos = 0;
+
+		// Iterate for $duration seconds or at least $minIterations number of iterations
+		$iterations = 0;
+		$startTime = microtime( true );
+		$currentTime = $startTime;
+		while ( $iterations < $minIterations || $currentTime - $startTime < $duration ) {
+			// Trigger some memory writing to trigger some bus activity
+			// This may create variance in the time between iterations
+			$bufPos = ( $bufPos + 13 ) % $bufLength;
+			$buffer[$bufPos] = ' ';
+			// Add the drift between this iteration and the last in as entropy
+			$nextTime = microtime( true );
+			$delta = (int)( ( $nextTime - $currentTime ) * 1000000 );
+			$data .= $delta;
+			// Every 100 iterations hash the data and entropy
+			if ( $iterations % 100 === 0 ) {
+				$data = sha1( $data );
+			}
+			$currentTime = $nextTime;
+			$iterations++;
+		}
+		$timeTaken = $currentTime - $startTime;
+		$data = $this->hash( $data );
+
+		wfDebug( __METHOD__ . ": Clock drift calculation " .
+			"(time-taken=" . ( $timeTaken * 1000 ) . "ms, " .
+			"iterations=$iterations, " .
+			"time-per-iteration=" . ( $timeTaken / $iterations * 1e6 ) . "us)\n" );
+		return $data;
+	}
+
+	/**
+	 * Return a rolling random state initially build using data from unstable sources
+	 * @return string A new weak random state
+	 */
+	protected 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 = $this->hash( $this->initialRandomState() );
+		}
+		// Generate a new random state based on the initial random state or previous
+		// random state by combining it with clock drift
+		$state = $this->driftHash( $state );
+		return $state;
+	}
+
+	/**
+	 * Decide on the best acceptable hash algorithm we have available for hash()
+	 * @throws MWException
+	 * @return String A hash algorithm
+	 */
+	protected function hashAlgo() {
+		if ( !is_null( $this->algo ) ) {
+			return $this->algo;
+		}
+
+		$algos = hash_algos();
+		$preference = array( 'whirlpool', 'sha256', 'sha1', 'md5' );
+
+		foreach ( $preference as $algorithm ) {
+			if ( in_array( $algorithm, $algos ) ) {
+				$this->algo = $algorithm;
+				wfDebug( __METHOD__ . ": Using the {$this->algo} hash algorithm.\n" );
+				return $this->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()" );
+	}
+
+	/**
+	 * Return the byte-length output of the hash algorithm we are
+	 * using in self::hash and self::hmac.
+	 *
+	 * @return int Number of bytes the hash outputs
+	 */
+	protected function hashLength() {
+		if ( is_null( $this->hashLength ) ) {
+			$this->hashLength = strlen( $this->hash( '' ) );
+		}
+		return $this->hashLength;
+	}
+
+	/**
+	 * Generate an acceptably unstable one-way-hash of some text
+	 * making use of the best hash algorithm that we have available.
+	 *
+	 * @param $data string
+	 * @return String A raw hash of the data
+	 */
+	protected function hash( $data ) {
+		return hash( $this->hashAlgo(), $data, true );
+	}
+
+	/**
+	 * Generate an acceptably unstable one-way-hmac of some text
+	 * making use of the best hash algorithm that we have available.
+	 *
+	 * @param $data string
+	 * @param $key string
+	 * @return String A raw hash of the data
+	 */
+	protected function hmac( $data, $key ) {
+		return hash_hmac( $this->hashAlgo(), $data, $key, true );
+	}
+
+	/**
+	 * @see self::wasStrong()
+	 */
+	public function realWasStrong() {
+		if ( is_null( $this->strong ) ) {
+			throw new MWException( __METHOD__ . ' called before generation of random data' );
+		}
+		return $this->strong;
+	}
+
+	/**
+	 * @see self::generate()
+	 */
+	public function realGenerate( $bytes, $forceStrong = false ) {
+		wfProfileIn( __METHOD__ );
+
+		wfDebug( __METHOD__ . ": Generating cryptographic random bytes for " . wfGetAllCallers( 5 ) . "\n" );
+
+		$bytes = floor( $bytes );
+		static $buffer = '';
+		if ( is_null( $this->strong ) ) {
+			// Set strength to false initially until we know what source data is coming from
+			$this->strong = true;
+		}
+
+		if ( strlen( $buffer ) < $bytes ) {
+			// If available make use of mcrypt_create_iv URANDOM source to generate randomness
+			// On unix-like systems this reads from /dev/urandom but does it without any buffering
+			// and bypasses openbasedir restrictions, so it's preferable to reading directly
+			// On Windows starting in PHP 5.3.0 Windows' native CryptGenRandom is used to generate
+			// entropy so this is also preferable to just trying to read urandom because it may work
+			// on Windows systems as well.
+			if ( function_exists( 'mcrypt_create_iv' ) ) {
+				wfProfileIn( __METHOD__ . '-mcrypt' );
+				$rem = $bytes - strlen( $buffer );
+				$iv = mcrypt_create_iv( $rem, MCRYPT_DEV_URANDOM );
+				if ( $iv === false ) {
+					wfDebug( __METHOD__ . ": mcrypt_create_iv returned false.\n" );
+				} else {
+					$buffer .= $iv;
+					wfDebug( __METHOD__ . ": mcrypt_create_iv generated " . strlen( $iv ) . " bytes of randomness.\n" );
+				}
+				wfProfileOut( __METHOD__ . '-mcrypt' );
+			}
+		}
+
+		if ( strlen( $buffer ) < $bytes ) {
+			// If available make use of openssl's random_pseudo_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
+			// http://git.php.net/?p=php-src.git;a=commitdiff;h=cd62a70863c261b07f6dadedad9464f7e213cad5
+			if ( function_exists( 'openssl_random_pseudo_bytes' )
+				&& ( !wfIsWindows() || version_compare( PHP_VERSION, '5.3.4', '>=' ) )
+			) {
+				wfProfileIn( __METHOD__ . '-openssl' );
+				$rem = $bytes - strlen( $buffer );
+				$openssl_bytes = openssl_random_pseudo_bytes( $rem, $openssl_strong );
+				if ( $openssl_bytes === false ) {
+					wfDebug( __METHOD__ . ": openssl_random_pseudo_bytes returned false.\n" );
+				} else {
+					$buffer .= $openssl_bytes;
+					wfDebug( __METHOD__ . ": openssl_random_pseudo_bytes generated " . strlen( $openssl_bytes ) . " bytes of " . ( $openssl_strong ? "strong" : "weak" ) . " randomness.\n" );
+				}
+				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
+					$this->strong = !!$openssl_strong;
+				}
+				wfProfileOut( __METHOD__ . '-openssl' );
+			}
+		}
+
+		// Only read from urandom if we can control the buffer size or were passed forceStrong
+		if ( strlen( $buffer ) < $bytes && ( function_exists( 'stream_set_read_buffer' ) || $forceStrong ) ) {
+			wfProfileIn( __METHOD__ . '-fopen-urandom' );
+			$rem = $bytes - strlen( $buffer );
+			if ( !function_exists( 'stream_set_read_buffer' ) && $forceStrong ) {
+				wfDebug( __METHOD__ . ": Was forced to read from /dev/urandom without control over the buffer size.\n" );
+			}
+			// /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 not storing that risks depleting the system's random pool.
+			// If stream_set_read_buffer is available set the chunk_size to the amount
+			// of data we need. Otherwise read 8k, php's default chunk_size.
+			if ( $urandom ) {
+				// php's default chunk_size is 8k
+				$chunk_size = 1024 * 8;
+				if ( function_exists( 'stream_set_read_buffer' ) ) {
+					// If possible set the chunk_size to the amount of data we need
+					stream_set_read_buffer( $urandom, $rem );
+					$chunk_size = $rem;
+				}
+				$random_bytes = fread( $urandom, max( $chunk_size, $rem ) );
+				$buffer .= $random_bytes;
+				fclose( $urandom );
+				wfDebug( __METHOD__ . ": /dev/urandom generated " . strlen( $random_bytes ) . " bytes of randomness.\n" );
+				if ( strlen( $buffer ) >= $bytes ) {
+					// urandom is always strong, set to true if all our data was generated using it
+					$this->strong = true;
+				}
+			} else {
+				wfDebug( __METHOD__ . ": /dev/urandom could not be opened.\n" );
+			}
+			wfProfileOut( __METHOD__ . '-fopen-urandom' );
+		}
+
+		// If we cannot use or generate enough data from a secure source
+		// use this loop to generate a good set of pseudo 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.
+		if ( strlen( $buffer ) < $bytes ) {
+			wfDebug( __METHOD__ . ": Falling back to using a pseudo random state to generate randomness.\n" );
+		}
+		while ( strlen( $buffer ) < $bytes ) {
+			wfProfileIn( __METHOD__ . '-fallback' );
+			$buffer .= $this->hmac( $this->randomState(), mt_rand() );
+			// This code is never really cryptographically strong, if we use it
+			// at all, then set strong to false.
+			$this->strong = false;
+			wfProfileOut( __METHOD__ . '-fallback' );
+		}
+
+		// 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 );
+
+		wfDebug( __METHOD__ . ": " . strlen( $buffer ) . " bytes of randomness leftover in the buffer.\n" );
+
+		wfProfileOut( __METHOD__ );
+		return $generated;
+	}
+
+	/**
+	 * @see self::generateHex()
+	 */
+	public function realGenerateHex( $chars, $forceStrong = false ) {
+		// 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( $this->generate( $bytes, $forceStrong ) );
+		// 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, $chars );
+	}
+
+	/** Publicly exposed static methods **/
+
+	/**
+	 * Return a singleton instance of MWCryptRand
+	 * @return MWCryptRand
+	 */
+	protected static function singleton() {
+		if ( is_null( self::$singleton ) ) {
+			self::$singleton = new self;
+		}
+		return self::$singleton;
+	}
+
+	/**
+	 * 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() {
+		return self::singleton()->realWasStrong();
+	}
+
+	/**
+	 * 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 int $bytes the number of bytes of random data to generate
+	 * @param bool $forceStrong Pass true if you want generate to prefer cryptographically
+	 *                          strong sources of entropy even if reading from them may steal
+	 *                          more entropy from the system than optimal.
+	 * @return String Raw binary random data
+	 */
+	public static function generate( $bytes, $forceStrong = false ) {
+		return self::singleton()->realGenerate( $bytes, $forceStrong );
+	}
+
+	/**
+	 * 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 int $chars the number of hex chars of random data to generate
+	 * @param bool $forceStrong Pass true if you want generate to prefer cryptographically
+	 *                          strong sources of entropy even if reading from them may steal
+	 *                          more entropy from the system than optimal.
+	 * @return String Hexadecimal random data
+	 */
+	public static function generateHex( $chars, $forceStrong = false ) {
+		return self::singleton()->realGenerateHex( $chars, $forceStrong );
+	}
+
+}