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   1  <?php
   2  declare(strict_types=1);
   3  namespace ParagonIE\ConstantTime;
   4  
   5  /**
   6   *  Copyright (c) 2016 - 2022 Paragon Initiative Enterprises.
   7   *  Copyright (c) 2014 Steve "Sc00bz" Thomas (steve at tobtu dot com)
   8   *
   9   *  Permission is hereby granted, free of charge, to any person obtaining a copy
  10   *  of this software and associated documentation files (the "Software"), to deal
  11   *  in the Software without restriction, including without limitation the rights
  12   *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  13   *  copies of the Software, and to permit persons to whom the Software is
  14   *  furnished to do so, subject to the following conditions:
  15   *
  16   *  The above copyright notice and this permission notice shall be included in all
  17   *  copies or substantial portions of the Software.
  18   *
  19   *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  20   *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  21   *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  22   *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  23   *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  24   *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  25   *  SOFTWARE.
  26   */
  27  
  28  /**
  29   * Class Base64UrlSafe
  30   * [A-Z][a-z][0-9]\-_
  31   *
  32   * @package ParagonIE\ConstantTime
  33   */
  34  abstract class Base64UrlSafe extends Base64
  35  {
  36  
  37      /**
  38       * Uses bitwise operators instead of table-lookups to turn 6-bit integers
  39       * into 8-bit integers.
  40       *
  41       * Base64 character set:
  42       * [A-Z]      [a-z]      [0-9]      -     _
  43       * 0x41-0x5a, 0x61-0x7a, 0x30-0x39, 0x2d, 0x5f
  44       *
  45       * @param int $src
  46       * @return int
  47       */
  48      protected static function decode6Bits(int $src): int
  49      {
  50          $ret = -1;
  51  
  52          // if ($src > 0x40 && $src < 0x5b) $ret += $src - 0x41 + 1; // -64
  53          $ret += (((0x40 - $src) & ($src - 0x5b)) >> 8) & ($src - 64);
  54  
  55          // if ($src > 0x60 && $src < 0x7b) $ret += $src - 0x61 + 26 + 1; // -70
  56          $ret += (((0x60 - $src) & ($src - 0x7b)) >> 8) & ($src - 70);
  57  
  58          // if ($src > 0x2f && $src < 0x3a) $ret += $src - 0x30 + 52 + 1; // 5
  59          $ret += (((0x2f - $src) & ($src - 0x3a)) >> 8) & ($src + 5);
  60  
  61          // if ($src == 0x2c) $ret += 62 + 1;
  62          $ret += (((0x2c - $src) & ($src - 0x2e)) >> 8) & 63;
  63  
  64          // if ($src == 0x5f) ret += 63 + 1;
  65          $ret += (((0x5e - $src) & ($src - 0x60)) >> 8) & 64;
  66  
  67          return $ret;
  68      }
  69  
  70      /**
  71       * Uses bitwise operators instead of table-lookups to turn 8-bit integers
  72       * into 6-bit integers.
  73       *
  74       * @param int $src
  75       * @return string
  76       */
  77      protected static function encode6Bits(int $src): string
  78      {
  79          $diff = 0x41;
  80  
  81          // if ($src > 25) $diff += 0x61 - 0x41 - 26; // 6
  82          $diff += ((25 - $src) >> 8) & 6;
  83  
  84          // if ($src > 51) $diff += 0x30 - 0x61 - 26; // -75
  85          $diff -= ((51 - $src) >> 8) & 75;
  86  
  87          // if ($src > 61) $diff += 0x2d - 0x30 - 10; // -13
  88          $diff -= ((61 - $src) >> 8) & 13;
  89  
  90          // if ($src > 62) $diff += 0x5f - 0x2b - 1; // 3
  91          $diff += ((62 - $src) >> 8) & 49;
  92  
  93          return \pack('C', $src + $diff);
  94      }
  95  }