[Summary view] [Print] [Text view]

   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 Base64DotSlashOrdered
  30   * ./[0-9][A-Z][a-z]
  31   *
  32   * @package ParagonIE\ConstantTime
  33   */
  34  abstract class Base64DotSlashOrdered extends Base64
  35  {
  36      /**
  37       * Uses bitwise operators instead of table-lookups to turn 6-bit integers
  38       * into 8-bit integers.
  39       *
  40       * Base64 character set:
  41       * [.-9]      [A-Z]      [a-z]
  42       * 0x2e-0x39, 0x41-0x5a, 0x61-0x7a
  43       *
  44       * @param int $src
  45       * @return int
  46       */
  47      protected static function decode6Bits(int $src): int
  48      {
  49          $ret = -1;
  50  
  51          // if ($src > 0x2d && $src < 0x3a) ret += $src - 0x2e + 1; // -45
  52          $ret += (((0x2d - $src) & ($src - 0x3a)) >> 8) & ($src - 45);
  53  
  54          // if ($src > 0x40 && $src < 0x5b) ret += $src - 0x41 + 12 + 1; // -52
  55          $ret += (((0x40 - $src) & ($src - 0x5b)) >> 8) & ($src - 52);
  56  
  57          // if ($src > 0x60 && $src < 0x7b) ret += $src - 0x61 + 38 + 1; // -58
  58          $ret += (((0x60 - $src) & ($src - 0x7b)) >> 8) & ($src - 58);
  59  
  60          return $ret;
  61      }
  62  
  63      /**
  64       * Uses bitwise operators instead of table-lookups to turn 8-bit integers
  65       * into 6-bit integers.
  66       *
  67       * @param int $src
  68       * @return string
  69       */
  70      protected static function encode6Bits(int $src): string
  71      {
  72          $src += 0x2e;
  73  
  74          // if ($src > 0x39) $src += 0x41 - 0x3a; // 7
  75          $src += ((0x39 - $src) >> 8) & 7;
  76  
  77          // if ($src > 0x5a) $src += 0x61 - 0x5b; // 6
  78          $src += ((0x5a - $src) >> 8) & 6;
  79  
  80          return \pack('C', $src);
  81      }
  82  }