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   1  <?php
   2  /**
   3   * Random_* Compatibility Library
   4   * for using the new PHP 7 random_* API in PHP 5 projects
   5   *
   6   * The MIT License (MIT)
   7   *
   8   * Copyright (c) 2015 - 2018 Paragon Initiative Enterprises
   9   *
  10   * Permission is hereby granted, free of charge, to any person obtaining a copy
  11   * of this software and associated documentation files (the "Software"), to deal
  12   * in the Software without restriction, including without limitation the rights
  13   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  14   * copies of the Software, and to permit persons to whom the Software is
  15   * furnished to do so, subject to the following conditions:
  16   *
  17   * The above copyright notice and this permission notice shall be included in
  18   * all copies or substantial portions of the Software.
  19   *
  20   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  21   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  22   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  23   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  24   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  25   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  26   * SOFTWARE.
  27   */
  28  
  29  if (!is_callable('random_bytes')) {
  30      /**
  31       * Windows with PHP < 5.3.0 will not have the function
  32       * openssl_random_pseudo_bytes() available, so let's use
  33       * CAPICOM to work around this deficiency.
  34       *
  35       * @param int $bytes
  36       *
  37       * @throws Exception
  38       *
  39       * @return string
  40       */
  41      function random_bytes($bytes)
  42      {
  43          try {
  44              /** @var int $bytes */
  45              $bytes = RandomCompat_intval($bytes);
  46          } catch (TypeError $ex) {
  47              throw new TypeError(
  48                  'random_bytes(): $bytes must be an integer'
  49              );
  50          }
  51  
  52          if ($bytes < 1) {
  53              throw new Error(
  54                  'Length must be greater than 0'
  55              );
  56          }
  57  
  58          /** @var string $buf */
  59          $buf = '';
  60          if (!class_exists('COM')) {
  61              throw new Error(
  62                  'COM does not exist'
  63              );
  64          }
  65          /** @var COM $util */
  66          $util = new COM('CAPICOM.Utilities.1');
  67          $execCount = 0;
  68  
  69          /**
  70           * Let's not let it loop forever. If we run N times and fail to
  71           * get N bytes of random data, then CAPICOM has failed us.
  72           */
  73          do {
  74              $buf .= base64_decode((string) $util->GetRandom($bytes, 0));
  75              if (RandomCompat_strlen($buf) >= $bytes) {
  76                  /**
  77                   * Return our random entropy buffer here:
  78                   */
  79                  return (string) RandomCompat_substr($buf, 0, $bytes);
  80              }
  81              ++$execCount;
  82          } while ($execCount < $bytes);
  83  
  84          /**
  85           * If we reach here, PHP has failed us.
  86           */
  87          throw new Exception(
  88              'Could not gather sufficient random data'
  89          );
  90      }
  91  }