<?php
/**
- * A static cryptographic random generator class used for generating secret keys
+ * 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
*/
-final class MWCryptRand {
+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
*/
- private static function initialRandomState() {
+ 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 and vary the system information of the state a bit more
+ // 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 ourself
+ $files[] = __FILE__;
+
+ // We must also have a parent folder, and with the usual file structure, a grandparent
+ $files[] = dirname( __FILE__ );
+ $files[] = dirname( dirname( __FILE__ ) );
+
+ // 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
+ $state .= realpath( $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' ) ) {
return $state;
}
+ /**
+ * Randomly hash data while mixing in clock drift data for randomness
+ *
+ * @param $data string 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 $minIerations 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 A new weak random state
+ * @return string A new weak random state
*/
- public static function randomState() {
+ 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 = self::initialRandomState();
+ $state = $this->hash( $this->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() );
+ // 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
*/
- private static function hashAlgo() {
- static $algo = null;
- if ( !is_null( $algo ) ) {
- return $algo;
+ protected function hashAlgo() {
+ if ( !is_null( $this->algo ) ) {
+ return $this->algo;
}
$algos = hash_algos();
foreach ( $preference as $algorithm ) {
if ( in_array( $algorithm, $algos ) ) {
- $algo = $algorithm; # assign to static
- return $algo;
+ $this->algo = $algorithm;
+ wfDebug( __METHOD__ . ": Using the {$this->algo} hash algorithm.\n" );
+ return $this->algo;
}
}
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
*/
- private static function hash( $data ) {
- return hash( self::hashAlgo(), $data, true );
+ 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
*/
- private static function hmac( $data, $key ) {
- return hash_hmac( self::hashAlgo(), $data, $key, true );
+ protected function hmac( $data, $key ) {
+ return hash_hmac( $this->hashAlgo(), $data, $key, true );
}
-
-
- private static $strong = null;
-
/**
- * Return a boolean indicating whether or not the source used for cryptographic
- * random bytes generation in the previously run generate* call
- * was cryptographically strong.
- *
- * @return bool Returns true if the source was strong, false if not.
+ * @see self::wasStrong()
*/
- public static function wasStrong() {
- if ( is_null( self::$strong ) ) {
+ public function realWasStrong() {
+ if ( is_null( $this->strong ) ) {
throw new MWException( __METHOD__ . ' called before generation of random data' );
}
- return self::$strong;
+ return $this->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
+ * @see self::generate()
*/
- public static function generate( $bytes ) {
+ public function realGenerate( $bytes, $forceStrong = false ) {
+ wfProfileIn( __METHOD__ );
+
+ wfDebug( __METHOD__ . ": Generating cryptographic random bytes for " . wfGetAllCallers( 5 ) . "\n" );
+
$bytes = floor( $bytes );
static $buffer = '';
- if ( is_null( self::$strong ) ) {
+ if ( is_null( $this->strong ) ) {
// Set strength to false initially until we know what source data is coming from
- self::$strong = true;
+ $this->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 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 and we failed to read enough data out of urandom make use
- // of openssl's random_pesudo_bytes method to attempt to generate randomness.
+ // 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
- if ( ( $bytes - strlen( $buffer ) > 0 )
- && function_exists( 'openssl_random_pseudo_bytes' )
+ // 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', '>=' ) )
) {
- $buffer .= openssl_random_pseudo_bytes( $bytes - strlen( $buffer ), $openssl_strong );
+ 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 ) >= $bytes ) {
// openssl tells us if the random source was strong, if some of our data was generated
// using it use it's say on whether the randomness is strong
- self::$strong = !!$openssl_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();
- // 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.
+ // 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 ) {
- $buffer .= self::hmac( self::randomState(), mt_rand() );
+ wfProfileIn( __METHOD__ . '-fallback' );
+ $buffer .= $this->hmac( $this->randomState(), mt_rand() );
// This code is never really cryptographically strong, if we use it
// at all, then set strong to false.
- self::$strong = false;
+ $this->strong = false;
+ wfProfileOut( __METHOD__ . '-fallback' );
}
// Once the buffer has been filled up with enough random data to fulfill
$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;
}
/**
- * 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
+ * @see self::generateHex()
*/
- public static function generateHex( $chars ) {
+ 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( self::generate( $bytes ) );
+ $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
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 $bytes int the number of bytes of random data to generate
+ * @param $forceStrong bool 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 $chars int the number of hex chars of random data to generate
+ * @param $forceStrong bool 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 );
+ }
+
}
dépôts / lhc / web / wiklou.git / blobdiff