Classes

• P2PEG

Functions

• sys_get_temp_dir

   1    2    3    4    5    6    7    8    9   10   11   12   13   14   15   16   17   18   19   20   21   22   23   24   25   26   27   28   29   30   31   32   33   34   35   36   37   38   39   40   41   42   43   44   45   46   47   48   49   50   51   52   53   54   55   56   57   58   59   60   61   62   63   64   65   66   67   68   69   70   71   72   73   74   75   76   77   78   79   80   81   82   83   84   85   86   87   88   89   90   91   92   93   94   95   96   97   98   99  100  101  102  103  104  105  106  107  108  109  110  111  112  113  114  115  116  117  118  119  120  121  122  123  124  125  126  127  128  129  130  131  132  133  134  135  136  137  138  139  140  141  142  143  144  145  146  147  148  149  150  151  152  153  154  155  156  157  158  159  160  161  162  163  164  165  166  167  168  169  170  171  172  173  174  175  176  177  178  179  180  181  182  183  184  185  186  187  188  189  190  191  192  193  194  195  196  197  198  199  200  201  202  203  204  205  206  207  208  209  210  211  212  213  214  215  216  217  218  219  220  221  222  223  224  225  226  227  228  229  230  231  232  233  234  235  236  237  238  239  240  241  242  243  244  245  246  247  248  249  250  251  252  253  254  255  256  257  258  259  260  261  262  263  264  265  266  267  268  269  270  271  272  273  274  275  276  277  278  279  280  281  282  283  284  285  286  287  288  289  290  291  292  293  294  295  296  297  298  299  300  301  302  303  304  305  306  307  308  309  310  311  312  313  314  315  316  317  318  319  320  321  322  323  324  325  326  327  328  329  330  331  332  333  334  335  336  337  338  339  340  341  342  343  344  345  346  347  348  349  350  351  352  353  354  355  356  357  358  359  360  361  362  363  364  365  366  367  368  369  370  371  372  373  374  375  376  377  378  379  380  381  382  383  384  385  386  387  388  389  390  391  392  393  394  395  396  397  398  399  400  401  402  403  404  405  406  407  408  409  410  411  412  413  414  415  416  417  418  419  420  421  422  423  424  425  426  427  428  429  430  431  432  433  434  435  436  437  438  439  440  441  442  443  444  445  446  447  448  449  450  451  452  453  454  455  456  457  458  459  460  461  462  463  464  465  466  467  468  469  470  471  472  473  474  475  476  477  478  479  480  481  482  483  484  485  486  487  488  489  490  491  492  493  494  495  496  497  498  499  500  501  502  503  504  505  506  507  508  509  510  511  512  513  514  515  516  517  518  519  520  521  522  523  524  525  526  527  528  529  530  531  532  533  534  535  536  537  538  539  540  541  542  543  544  545  546  547  548  549  550  551  552  553  554  555  556  557  558  559  560  561  562  563  564  565  566  567  568  569  570  571  572  573  574  575  576  577  578  579  580  581  582  583  584  585  586  587  588  589  590  591  592  593  594  595  596  597  598  599  600  601  602  603  604  605  606  607  608  609  610  611  612  613  614  615  616  617  618  619  620  621  622  623  624  625  626  627  628  629  630  631  632  633  634  635  636  637  638  639  640  641  642  643  644  645  646  647  648  649  650  651  652  653  654  655  656  657  658  659  660  661  662  663  664  665  666  667  668  669  670  671  672  673  674  675  676  677  678  679  680  681  682  683  684  685  686  687  688  689  690  691  692  693  694  695  696  697  698  699  700  701  702  703  704  705  706  707  708  709  710  711  712  713  714  715  716  717  718  719  720  721  722  723  724  725  726  727  728  729  730  731  732  733  734  735  736  737  738  739  740  741  742  743  744  745  746  747  748  749  750  751  752  753  754  755  756  757  758  759  760  761  762  763  764  765  766  767  768  769  770  771  772  773  774  775  776  777  778  779  780  781  782  783  784  785  786  787  788  789  790  791  792  793  794  795  796  797  798  799  800  801  802  803  804  805  806  807  808  809  810  811  812  813  814  815  816  817  818  819  820  821  822  823  824  825  826  827  828  829  830  831  832  833  834  835  836  837  838  839  840  841  842  843  844  845  846  847  848  849  850  851  852  853  854  855  856  857  858  859  860  861  862  863  864  865  866  867  868  869  870  871  872  873  874  875  876  877  878  879  880  881  882  883  884  885  886  887  888  889  890  891  892  893  894  895  896  897  898  899  900  901  902  903  904  905  906  907  908  909  910  911  912  913  914  915  916  917  918  919  920  921  922  923  924  925  926  927  928  929  930  931  932  933  934  935  936  937  938  939  940  941  942  943  944  945  946  947  948  949  950  951  952  953  954  955  956  957  958  959  960  961  962  963  964  965  966  967  968  969  970  971  972  973  974  975  976  977  978  979  980  981  982  983  984  985  986  987  988  989  990  991  992  993  994  995  996  997  998  999 1000 1001 1002 1003 1004 

<?php
/*!
 *  Peer to Peer Entropy Generator
 *  or Random numbers generator with p2p seeding
 *
 *  This class uses a combination of system data, client supplied data,
 *  some PRNGs available to PHP and timing to generate unpredictable
 *  entropy data.
 *  *
 *  Each pear adds to the entropy, by suppling variable data with the request (in purpos or not)
 *  and by the fact of connecting to the server (the exact request time is also accounted).
 *  *
 *  For connecting pears there is no way to know about internal server state.
 *  *
 *  For anyone trying to compute the state of the entropy data at a given point in time,
 *  or trying to guess
 *
 *  @TODO
 *
 *  1.  To improve the entropy unpredictability, I intend to create system
 *      where multiple machines periodically exchange entropy.
 *      Each pear gets entropy and gives entropy at the same time
 *      with a simple GET request like this one:
 *
 *      curl https://DUzun.Me/entropy/<hash(random_func().$secret)>
 *
 *
 *  2.  Seed /dev/random and update entropy count, to improve system performance
 *
 *
 *  3.  Count the amount of entropy generated
 *
 *
 *  @version 0.3.5
 *  @author Dumitru Uzun (DUzun.Me)
 *
 */

class P2PEG {
    public static $version = '0.3.5';

    // First start timestamp
    public static $start_ts;

    // Singleton instance
    protected static $instance;

    /// Path to a file where to store state data
    public $state_file;

    public $debug = false;

    /// Use first available hash alg from the list
    public $hash = array('sha512', 'sha256', 'sha128', 'sha1', 'md5');

    // Padding for HMAC-HASH
    private $_opad, $_ipad;

    // If true, call seedRandomDev() on __destruct
    public $seedSys = true;

    // Seed for rand32() & rand64() methods
    public $rs00 = 0;
    public $rs01 = 0;
    public $rs10 = 0;
    public $rs11 = 0;

    // State values
    private   $_state;
    protected $_state_mtime;
    protected $_clientEntropy;
    protected $_serverEntropy;
    protected $_serverEEntropy;
    protected $_filesystemEntropy;

    // internal buffer
    private $_b = ''; // data
    private $_l = 0;  // available (unused) length

    // How many degimal digits fit in one int
    protected static $int_len;
    // -------------------------------------------------
    /// Get the singleton instance
    public static function instance($secret=NULL) {
        if(!isset(self::$instance)) {
            self::$instance = new self($secret);
        }
        return self::$instance;
    }
    // -------------------------------------------------
    /// @param (string)$secret - A secred string, should be unique on each installation (: http://xkcd.com/221/ :)
    public function __construct($secret=',!8L_J:UW~l\'ACt:7c05!R9}~>yb!gPP=|(@FBny\'ao/&-\jVs') {
        // parent::__construct();
        isset(self::$start_ts) or self::$start_ts = microtime(true);
        $this->setSecret($secret);
        isset(self::$int_len) or self::$int_len = round(PHP_INT_SIZE * log10(256));

        $this->seedSys = !$this->isWindows();
    }

    public function __destruct() {
        // parent::__destruct();

        // Save state to a file
        $this->saveState();

        // Influence /dev/urandom and /dev/random
        if($this->seedSys) $this->seedRandomDev(__METHOD__);
    }
    // -------------------------------------------------
    public function saveState($sf=NULL) {
        if(!$this->_state) return false; // Nothing to save
        if(!$sf) $sf = $this->state_file;
        if(!$sf) return false; // No where to save

        static $oldPHP;
        isset($oldPHP) or $oldPHP = version_compare(PHP_VERSION, '5.3.0') < 0;
        // If meanwhile state file changed, don't loose that entropy
        $oldPHP ? clearstatcache() : clearstatcache(true, $sf);

        $flags = 1;
        if(@filemtime($sf) != $this->_state_mtime) {
            $flags |= FILE_APPEND;
        }
        // @TODO: Watch for state_file size if the server is very busy

        return @$this->flock_put_contents($sf, $this->_state, $flags);
    }
    // -------------------------------------------------
    public function warmup($secret=NULL) {
        isset($secret) and $this->setSecret($secret);
        $this->state();
        // $this->serverEntropy();
        // $this->clientEntropy();
    }

    // -------------------------------------------------
    /**
     *  Seed P2PEG with some entropy.
     */
    public function seed($seed=NULL) {
        $ret = $this->state()
               . $seed
               . $this->dynEntropy()
        ;
        $ret = $this->hash($ret);
        $this->_state ^= $ret;
        $this->_b = $ret;
        $this->_l = strlen($ret);
        return $ret;
    }

    // -------------------------------------------------
    /**
     *  Return a random binary string of specified length.
     */
    public function str($len=NULL) {
        // If buffer is empty, fill it
        if(!($l = $this->_l)) {
            $this->seed($len);
            $l = $this->_l;
        }
        // If we have to return exactly what is in the buffer, return quickly
        if(!isset($len) || $len == $l) {
            // remove used data from buffer to avoid reusing it
            $ret = $l < strlen($this->_b) ? substr($this->_b, 0, $l) : $this->_b;
            // empty the buffer
            $this->_b = '';
            $this->_l = 0;
            return $ret;
        }

        $ret = '';
        // If we need more data than we have in the buffer, generate some more
        if($l < $len) {
            // remove used data from buffer to avoid reusing it
            if($l < strlen($this->_b)) $this->_b = substr($this->_b, 0, $l);

            do {
                $ret .= $this->_b; // save what is in the buffer
                $this->seed($l);   // fill it again
                $l += $this->_l;   // the sum of what we have saved in $ret and what is in the buffer
            } while($l < $len);
        }

        // If buffer has more data then we need
        if($len < $l) {
            // how much data we don't need from buffer ?
            $this->_l = $l - $len;
            // get only that much we need from buffer and leave the rest for others
            $ret .= substr($this->_b, $this->_l, $len);
        }
        // else buffer has exactly how much data we need - grab it all
        else {
            $ret .= $this->_b;
            // empty the buffer
            $this->_b = '';
            $this->_l = 0;
        }
        return $ret;
    }


    /**
     *  Hex encoded string
     */
    public function hex($len=NULL) {
        $l = isset($len) ? ($len+1) >> 1 : $len;
        $ret = $this->str($l);
        $ret = bin2hex($ret);
        return !isset($len) || strlen($ret) == $len
            ? $ret
            : substr($ret, 0, $len)
        ;
    }


    /**
     *  Base64 encoded text for URL
     */
    public function text($len=NULL) {
        $l = isset($len) ? ceil((float)$len * 3.0 / 4.0) : NULL;
        $ret = $this->bin2text($this->str($l));
        if(isset($len) && strlen($ret) > $len) $ret = substr($ret, 0, $len);
        return $ret;
    }


    /**
     *  Return a random 16 bit integer.
     *
     *  @return (int)random
     */
    public function int16() {
        $r = unpack('s', $this->str(2));
        return reset($r);
    }

    /**
     *  Return a random 32 bit integer.
     *
     *  @return (int)random
     */
    public function int32() {
        $r = unpack('l', $this->str(4));
        return reset($r);
    }

    /**
     *  Return a random integer.
     *
     *  @param (int)$size - number of bytes used to generate the integer [1..PHP_INT_SIZE].
     *                      Defaults to PHP_INT_SIZE (4 or 8, depending on system)
     *      Ex. If $size == 1, the result is a number from interval [0..255].
     *          If $size == 3, the result is a number from interval [0..16777215].
     *
     *  @return (int)random
     *
     */
    public function int($size=NULL) {
        $s = isset($size) ? $size : PHP_INT_SIZE;
        $src = $this->str($s);
        $r = 0;
        for(;$s--;) $r = ($r << 8) | ord(substr($src, $s, 1));
        return $r;
    }

    // -------------------------------------------------
    /**
     *  Pseudo-random 32bit integer numbers generator.
     *
     *  This function produces same result as $this->int32(),
     *  but is much faster at generating long strings of random numbers,
     *  and uses less entropy as well.
     *
     *  @source http://en.wikipedia.org/wiki/Random_number_generation
     *
     *  @return  (int)random
     */
    public function rand32() {
        $rs10 = $this->rs10;
        $rs00 = $this->rs00;

        // Seed if necessary
        while(!$rs10 || $rs10 == 0x464fffff) {
            /* must not be zero, nor 0x464fffff */
            $rs10 = $this->int32() ^ $this->int32();
        }
        while(!$rs00 || $rs00 == 0x9068ffff) {
            /* must not be zero, nor 0x9068ffff */
            $rs00 = $this->int32() ^ $this->int32();
        }

        $rs00 = 0x9069 * ($rs00 & 0xFFFF) + ($rs00 >> 16);
        $rs10 = 0x4650 * ($rs10 & 0xFFFF) + ($rs10 >> 16);
        $ret = ($rs00 << 16) + $rs10;  /* 32-bit result */

        $this->rs10 = $rs10;
        $this->rs00 = $rs00;

        // handle overflow:
        // in PHP at overflow (int32) -> (float)
        return $ret | 0;
    }

    // -------------------------------------------------
    /**
     *  Pseudo-random 64bit integer numbers generator.
     *
     *  @source  http://vigna.di.unimi.it/ftp/papers/xorshiftplus.pdf
     *
     *  @return (int)random
     */
    public function rand64() {
        $s10 = $this->rs00;
        $s11 = $this->rs01;
        $s00 = $this->rs10;
        $s01 = $this->rs11;

        $m = 0xFFFFFFFF;

        // Seed if necessary
        while(!$s10 || !$s11) {
            $s10 = $this->int32();
            $s11 = $this->int32();
        }
        while(!$s00 || !$s01) {
            $s00 = $this->int32();
            $s01 = $this->int32();
        }

        $this->rs00 = $s00;
        $this->rs01 = $s01;

        // $s1 ^= $s1 << 23;
        $s11 ^= ($s11 << 23) & $m | ($s10 >> 9);
        $s10 ^= ($s10 << 23) & $m;

        // $s1 ^= $s1 >> 17;
        $s10 ^= ($s11 << 15) & $m | ($s10 >> 17);
        $s11 ^= $s11 >> 17;

        // $s1 ^= $s0;
        $s10 ^= $s00;
        $s11 ^= $s01;

        // $s1 ^= $s0 >> 26;
        $s10 ^= ($s01 << 8) & $m | ($s00 >> 26);
        $s11 ^= $s01 >> 26;

        $this->rs10 = $s10;
        $this->rs11 = $s11;

        return (($this->rs01 + $this->rs11) << 32) + ($this->rs00 + $this->rs10);
    }
    // -------------------------------------------------
    /**
     *  Generate and serve to client a random bitmap image.
     *
     *  This method helps to visually inspect a random number generator (RNG).
     *  It is not enough to know how good the RNG is,
     *  but it can tell that the RNG is bad or something is wrong.
     *
     *  @param (int)$width of the image
     *  @param (int)$height of the image
     *  @param (str)$meth - a method of this class to generate data
     *  @param (int)$itemSize in bits - size of each number or char generated by $meth. Defaults to 8 for string and 32 for int
     *
     *  @note Requires the GD Library
     *
     *  Inspired by  http://boallen.com/random-numbers.html
     *
     */
    public function servImg($width=64, $height=64, $meth='rand32', $itemSize=NULL) {
        header("Content-type: image/png");
        $im = imagecreatetruecolor($width, $height) or die("Cannot Initialize new GD image stream");
        $white = imagecolorallocate($im, 255, 255, 255);
        // @TODO: Check if $method is safe to display to client
        $g = $this->$meth();
        $iss = is_string($g); // string or int32
        if($iss) {
            $p = strlen($g);
            $r = ord(substr($g, --$p, 1));
            $bitSize = empty($itemSize) ? 8 : $itemSize; // 1 bytes == 8 bits
        }
        else {
            $r = $g;
            $bitSize = empty($itemSize) ? 32 : $itemSize; // 4 bytes == 32 bits
        }
        $i = $bitSize;

        for($y = 0; $y < $height; $y++) {
            for($x = 0; $x < $width; $x++) {
                if($i == 0) {
                    if($iss) {
                        if(!$p) {
                            $g = $this->$meth();
                            $p = strlen($g);
                        }
                        $r = ord(substr($g, --$p, 1));
                    }
                    else {
                        $r = $this->$meth();
                    }
                    $i = $bitSize;
                }
                if($r & 1) {
                    imagesetpixel($im, $x, $y, $white);
                }
                $r >>= 1;
                --$i;
            }
        }
        imagepng($im);
        imagedestroy($im);
    }

    // -------------------------------------------------
    public function setSecret($key) {
        $size = 64;
        $l = strlen($key);
        if($size < $l) {
            $key = hash('sha1', $key, true);
            if($key === FALSE) return $key;
            $l = strlen($key);
        }
        if($l < $size) {
            $key = str_pad($key, $size, chr(0));
        }
        else {
            $key = substr($key, 0, -1) . chr(0);
        }

        $this->_opad = str_repeat(chr(0x5C), $size) ^ $key;
        $this->_ipad = str_repeat(chr(0x36), $size) ^ $key;

        // Empty the buffer
        $this->_l = 0;
    }
    // -------------------------------------------------
    /**
     *   Quickly get some dynamic entropy.
     */
    public function dynEntropy($quick=true) {
        $_entr = array();

        $_entr[$this->packInt(+substr(microtime(), 2, 6))] = 'microtime';
        $_entr[$this->packInt(rand())] = 'rand';

        // Get some data from mt_rand()
        $r = array();
        $l = rand(1,8);
        for ($i = 0; $i < $l; ++$i) $r[] = pack('S', mt_rand(0, 0xFFFF));
        $r = implode('', $r);
        $_entr[$r] = 'mt_rand';

        // System performance/load indicator
        $r = (microtime(true)-self::$start_ts)*1000;
        $_entr[$this->packFloat($r)] = 'delta';

        $_entr = implode('', array_keys($_entr));
        return $_entr;
    }

    // -------------------------------------------------
    /*
     * Each connecting client brings in some entropy and influences internal state.
     *
     */
    public function clientEntropy() {
        if(!isset($this->_clientEntropy)) {
            if(strncmp(php_sapi_name(), 'cli', 3) == 0) {
                global $argv;
                $_entr = implode('', $argv);
                $_entr = $_entr ? $this->hash($_entr,true) : '';
                $this->_clientEntropy = $_entr;
                return $_entr;
            }

            $_entr = array();
            foreach(array(
                'REQUEST_URI',
                'HTTP_COOKIE',
                'HTTP_ACCEPT_LANGUAGE',
                'HTTP_ACCEPT',
                'HTTP_USER_AGENT',
                'HTTP_CACHE_CONTROL',
            ) as $t) {
                $r = $this->env($t) and
                $_entr[$r] = $t;
            }
            if(empty($_COOKIE[session_name()]) and $r = session_id()) $_entr[$r] = 'sesid'; // If session just initialized, there is no session id in cookie

            // HTTP_COOKIE and REQUEST_URI might contain private data - hash/hide it at this point
            $_entr = implode('', array_keys($_entr));
            $_entr = array($this->hash($_entr,true)=>'HTTP');

            foreach(array(
                'REMOTE_ADDR',
                'HTTP_CLIENT_IP', // client might be behind proxy
                'HTTP_X_FORWARDED_FOR',
                'SERVER_ADDR', // server might have more IPv4 addresses - connecting to one of two ADDR is a bit of entropy
            ) as $t) {
                $r = $this->env($t) and
                $_entr[$this->packIP4($r)] = $t;
            }
            $r = ($this->env('REMOTE_PORT')+1)*($this->env('SERVER_PORT')+1);
            $_entr[$this->packInt($r)] = 'port*port';

            if($r = $this->env('REQUEST_TIME_FLOAT')) {
                $_entr[$this->packFloat($r)] = 'rtf';
            }
            else
            if($r = $this->env('REQUEST_TIME')) {
                $_entr[$this->packInt(+$r)] = 'rt';
            }

            $_entr = implode('', array_keys($_entr));
            $this->_clientEntropy = $_entr;
        }
        return $this->_clientEntropy;
    }

    // -------------------------------------------------
    /*
     * Entropy private to server
     */
    public function serverEntropy() {
        if(!isset($this->_serverEntropy)) {
            $_entr = array();
            $_entr[php_uname('s')] = 's'; // 'Linux' - less useful, cause it never changes
            $_entr[php_uname('r')] = 'r';
            $_entr[php_uname('v')] = 'v';
            $_entr[phpversion()] = 'php';
            $_entr[php_sapi_name()] = 'sapi';
            $_entr[$this->packIP4(self::$version)] = 'ver';

            $t = getmypid()   and $_entr[$this->packInt($t)] = 'pid';
            $t = getmyuid()   and $_entr[$this->packInt($t)] = 'uid';
            $t = getlastmod() and $_entr[$this->packInt($t)] = 'lastmod';

            if(function_exists('openssl_random_pseudo_bytes')) {
                $t = openssl_random_pseudo_bytes(32) and
                $_entr[$t] = 1;
            }

            if(function_exists('random_bytes')) {
                $t = random_bytes(32) and
                $_entr[$t] = 'random_bytes';
            }
            else
            // mcrypt_create_iv() is Deprecated in PHP7.1 and replaced by random_bytes()
            if(function_exists('mcrypt_create_iv')) {
                $t = mcrypt_create_iv(32) and
                $_entr[$t] = 'mcrypt_create_iv';
            }

            $_entr[$this->packFloat(self::$start_ts)] = 'start';

            $_entr = implode('', array_keys($_entr));
            $this->_serverEntropy = $_entr;
        }
        return $this->_serverEntropy;
    }

    // -------------------------------------------------
    public function filesystemEntropy($dirs=NULL, $maxRead=0) {
        if(!isset($dirs)) {
            if(isset($this->_filesystemEntropy)) return $this->_filesystemEntropy;
            $_save_result = true;
            $dirs = array(session_save_path(), sys_get_temp_dir(), $this->env('DOCUMENT_ROOT'));
        }
        if(!$maxRead) {
            $maxRead = rand(100,500);
        }
        if(!$dirs) return false;

        if(!is_array($dirs)) $dirs = array($dirs);

        // Unique
        $dirs = array_flip($dirs);

        $buf = '';
        foreach($dirs as $dir => $v) if($d = @opendir($dir)) {
            $h = $this->strxor((($v+1)*$maxRead) . $d . $this->packInt(filemtime($dir)), $dir);
            $i = $maxRead;
            while($i-- > 0 and $f = readdir($d)) if($f != '.' && $f != '..') {
                $h = $this->strxor($h, $f);
            }
            $buf .= $h;
            closedir($d);
        }
        $this->_filesystemEntropy = $buf;
        return $buf;
    }

    // -------------------------------------------------
    /**
     *  Server Expensive entropy.
     *
     *  Note: Contains serverEntropy()
     *
     */
    public function serverEEntropy($autoseed=true) {
        if(!isset($this->_serverEEntropy)) {
            $_entr = array();
            $len = 64;

            $is_win = $this->isWindows();

            $cmds = $is_win
                ? array('net stats srv')
                : array('uptime', 'iostat', 'ps');

            // Some system data
            foreach ($cmds as $cmd) {
                $s = array();
                @exec($cmd, $s, $ret);
                if($s && is_array($s) && $ret === 0) {
                    foreach($s as $v) {
                        if(false !== preg_match_all('/[1-9]+/', $v, $m) && !empty($m[0])) {
                            $m = implode('', $m[0]);
                            $_entr[$this->packInt($m)] = $cmd;
                        }
                    }
                }
            }

            // /dev/random
            if( false !== ($f = @fopen('/dev/random', 'r')) ) {
                stream_set_blocking($f, 0);
                if(false !== ($r = @fread($f, $len))) {
                    $_entr[$r] = '/dev/random';
                }
                fclose($f);
            }

            if($r = $this->filesystemEntropy()) {
                $_entr[$r] = 'fs';
            }

            $_entr = implode('', array_keys($_entr));

            // Don't waste the chance to seed our P2PEG with some extra entropy
            $autoseed and $this->seed($_entr);

            $_entr .= $this->serverEntropy();

            $this->_serverEEntropy = $_entr;
        }
        return $this->_serverEEntropy;
    }

    // -------------------------------------------------
    public function networkEntropy($autoseed=true) {
        $_entr = array();
        $len = 256;

        $t1 = microtime(true);

        // HTTPS is better for security, but slower.
        $proto = 'https';

        // www.random.org
        if( false !== ($r = @file_get_contents($proto.'://www.random.org/cgi-bin/randbyte?format=f&nbytes=' . $len)) ) {
            $_entr[$r] = 'random.org';
        }
        else
        // jsonlib.appspot.com
        if ( false !== ($r = file_get_contents($proto.'://jsonlib.appspot.com/urandom?bytes='.$len)) ) {
            $t = json_decode($r) and
            $t = $t->urandom and $r = $t;
            $_entr[$r] = 'jsonlib.appspot.com';
        }

        // @TODO: read from other P2PEG servers

        $delta = microtime(true) - $t1;

        $_entr[$this->packFloat($delta)] = 'delta';

        $_entr = implode('', array_keys($_entr));

        // Don't waste the chance to seed our P2PEG with some extra entropy
        $autoseed and $this->seed($_entr);

        return $_entr;
    }

    // -------------------------------------------------
    /**
     *  Since this class is designed to run as quick as posible,
     *  this method is not called by default.
     *  *
     *  You should call this method only in places where speed is not
     *  critical (ex. on cron, in a background request)
     *
     */
    public function expensiveEntropy($autoseed=true) {
        $_entr = '';

        if($r = $this->serverEEntropy(false)) {
            $_entr .= $r;
        }

        if($r = $this->networkEntropy(false)) {
            $_entr .= $r;
        }

        // Don't waste the chance to seed our P2PEG with some extra entropy
        $autoseed and $this->seed($_entr);

        return $_entr;
    }

    // -------------------------------------------------

    public function state() {
        if(!isset($this->_state)) {
            if(!$this->state_file) {
                $this->state_file = sys_get_temp_dir() . DIRECTORY_SEPARATOR . __CLASS__ . '.dat';
            }
            $state_file = $this->state_file;
            if($state_file) {
                if(file_exists($state_file)) {
                    // We could use filemtime($state_file) as entropy too
                    $this->_state_mtime = filemtime($state_file);
                    $this->_state = $this->flock_get_contents($state_file);
                }
                else {
                    $this->_state_mtime = 0;
                    is_dir($dir = dirname($state_file)) or mkdir($dir, 0600, true);
                }
            }

            // Seed the state
            $seed = $this->hash($this->clientEntropy() . $this->dynEntropy() . $this->serverEntropy());

            // No state - init it with some initial entropy
            if(!$this->_state) {
                $this->_state = $this->hash(
                    $this->serverEEntropy(false) // could be a bit expensive, but it is run only the first time
                );
            }
            // Update state before next save
            else {
                // Align state value with our hash function
                if(strlen($this->_state) < strlen($seed)) {
                    $this->_state = $this->hash($seed.$this->_state);
                }
            }

            // New state depends on previous state and the entropy of current request
            $this->_state ^= $seed;
        }
        return $this->_state;
    }

    // -------------------------------------------------

    public function hash($str, $raw=true) {
        $str = $this->_ipad . $str;
        if(is_array($this->hash)) {
            foreach($this->hash as $h) {
                $ret = hash($h, $str, true);
                if($ret !== false) {
                    $this->hash = $h;
                    return hash($h, $this->_opad . $ret, $raw);
                }
            }
            $this->hash = 'sha1'; // minimum required sha1
        }
        $ret = hash($this->hash, $this->_opad . hash($this->hash, $this->_ipad . $str, true), $raw);
        return $ret;
    }
    // -------------------------------------------------

    // Helper methods:

    public function packIP4($ip) {
        $r = '';
        $ip = explode('.', $ip);
        $hasNaN = false;
        foreach($ip as $i) {
            $t = intval($i=trim($i));
            if ( !$t && strncmp($i, '0', 1) ) {
                $hasNaN = true;
                continue;
            }
            $r .= chr($t & 0xFF);
        }
        if ( $hasNaN && !strlen($r) ) return false;
        return $r;
    }

    public function packInt($int) {
        $r = '';
        if(is_string($int)) {
            $int = ltrim($int, '0.');
            if(strlen($int) > self::$int_len) {
                $i = str_split($int, self::$int_len);
                foreach($i as $v) $r .= $this->packInt(intval($v));
                return $r;
            }
            $int = +$int;
        }
        // When $int is bigger then int32 (on x86 it is converted to float), shift cuts out some bits.
        // Split the number into 3 pieces of 24 bits ($int is a 53 bit precision double)
        if ( $int > PHP_INT_MAX + 1 ) {
            $m = ~(-1<<((PHP_INT_SIZE-1)<<3));
            return $this->packInt($int & $m) .
                   $this->packInt(($int /= $m+1) & $m) .
                   $this->packInt(($int / ($m+1)) | 0) ;
        }

        $m = $int < 0 ? -1 : 0;
        while($int != $m) {
            $r .= chr($int & 0xFF);
            $int >>= 8;
        }
        return $r;
    }

    public function packFloat($float) {
        $t = explode('.', $float, 2);
        return count($t) == 2
            ? $this->packInt($t[1].$t[0]).$this->packInt(strlen($t[1]))
            : $this->packInt($float)
        ;
    }

    // -------------------------------------------------
    public function bin2text($bin) {
        $text = strtr(rtrim(base64_encode($bin), '='), '+/', '-_');
        return $text;
    }

    public function text2bin($text, $strict=false) {
        $bin = base64_decode(strtr($text, '-_', '+/'), $strict);
        return $bin;
    }

    // -------------------------------------------------
    public function strxor($a,$b) {
        $m = strlen($a);
        $n = strlen($b);
        if($m != $n) {
            if(!$m || !$n) return $a . $b;
            if($n < $m) {
                $b = str_repeat($b, floor($m / $n)) . substr($b, 0, $m % $n);
            }
            else {
                $a = str_repeat($a, floor($n / $m)) . substr($a, 0, $n % $m);
            }
        }
        return $a ^ $b;
    }
    // -------------------------------------------------
    public function env($n) {
        $r = getenv($n);
        if($r === false) $r = isset($_SERVER[$n]) ? $_SERVER[$n] : false;
        return $r;
    }

    // -------------------------------------------------
    /**
     *   Write some random bits to /dev/random or /dev/urandom
     *
     *   From `man 4 random`:
     *      Writing to /dev/random or /dev/urandom will update the entropy pool
     *      with the data written, but this will not result in a higher entropy
     *      count.  This means that it will impact the contents read from both
     *      files, but it will not make reads from /dev/random faster.
     */
    public function seedRandomDev($seed=NULL) {
        $this->seedSys = false; // system random seeded, don't seed again on __destruct()

        // Aditional entropy
        if(isset($seed)) {
            $this->seed($seed);
        }
        $ret = $this->frand_put_content('/dev/random') or
        $ret = $this->frand_put_content('/dev/urandom');
        return $ret;
    }

    // -------------------------------------------------
    /**
     *   Write $length bytes of random data to $filename file.
     *
     *   If $length is not specified, write data from internal buffer.
     */
    public function frand_put_content($filename, $length=NULL, $append=false) {
        $f = @fopen($filename, $append?'c':'w');
        if($f) {
            if(empty($length)) {
                $str = strlen($this->_b) ? $this->_b : $this->seed($filename.$append);
            }
            else {
                $str = $this->str($length);
            }
            if($append) fseek($f, 0, SEEK_END);
            $ret = fwrite($f, $str);
            fclose($f);
            return $ret;
        }
        return false;
    }

    // -------------------------------------------------
    /**
     * Lock with retries
     *
     * @param (resource)$fp - Open file pointer
     * @param (int) $lock - Lock type
     * @param (int) $timeout_ms - Timeout to wait for unlock in miliseconds
     *
     * @return true on success, false on fail
     *
     * @author Dumitru Uzun
     *
     */
    function do_flock($fp, $lock, $timeout_ms=384) {
        $l = flock($fp, $lock);
        if( !$l && ($lock & LOCK_UN) != LOCK_UN ) {
            $st = microtime(true);
            $m = min( 1e3, $timeout_ms*1e3);
            $n = min(64e3, $timeout_ms*1e3);
            if($m == $n) $m = ($n >> 1) + 1;
            $timeout_ms = (float)$timeout_ms / 1000;
            // If lock not obtained sleep for 0 - 64 milliseconds, to avoid collision and CPU load
            do {
                usleep($t = rand($m, $n));
                $l = flock($fp, $lock);
            } while ( !$l && (microtime(true)-$st) < $timeout_ms );
        }
        return $l;
    }

    function flock_put_contents($fn, $cnt, $block=false) {
        // return file_put_contents($fn, $cnt, $block & FILE_APPEND);
        $ret = false;
        if( $f = fopen($fn, 'c+') ) {
            $app = $block & FILE_APPEND and $block ^= $app;
            if( $block ? $this->do_flock($f, LOCK_EX) : flock($f, LOCK_EX | LOCK_NB) ) {
                if(is_array($cnt) || is_object($cnt)) $cnt = serialize($cnt);
                if($app) fseek($f, 0, SEEK_END);
                if(false !== ($ret = fwrite($f, $cnt))) {
                    fflush($f);
                    ftruncate($f, ftell($f));
                }
                flock($f, LOCK_UN);
            }
            fclose($f);
        }
        return $ret;
    }

    function flock_get_contents($fn, $block=false) {
       // return file_get_contents($fn);
       $ret = false;
       if( $f = fopen($fn, 'r') ) {
           if( flock($f, LOCK_SH | ($block ? 0 : LOCK_NB)) ) {
              $s = 1 << 14 ;
              do $ret .= $r = fread($f, $s); while($r !== false && !feof($f));
              if($ret == NULL && $r === false) $ret = $r;
              // filesize result is cached
              flock($f, LOCK_UN);
           }
           fclose($f);
       }
       return $ret;
    }
    // -------------------------------------------------
    function isWindows() {
        return getenv('WINDIR') || getenv('windir');
        // return DIRECTORY_SEPARATOR != '/';
    }
    // -------------------------------------------------

}

if(!function_exists('sys_get_temp_dir')) {
    function sys_get_temp_dir() {
        static $dir;
        if(!isset($dir)) {
            if(!empty($_ENV['TMP'])) { return $dir = realpath($_ENV['TMP']); }
            if(!empty($_ENV['TMPDIR'])) { return $dir = realpath( $_ENV['TMPDIR']); }
            if(!empty($_ENV['TEMP'])) { return $dir = realpath( $_ENV['TEMP']); }
            $tempfile = tempnam(__FILE__, '');
            if(file_exists($tempfile)) {
                unlink($tempfile);
                return $dir = realpath(dirname($tempfile));
            }
            $dir = false;
        }
        return $dir;
    }
}



?>