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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 Base64DotSlash
  30   * ./[A-Z][a-z][0-9]
  31   *
  32   * @package ParagonIE\ConstantTime
  33   */
  34  abstract class Base64DotSlash 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       * ./         [A-Z]      [a-z]     [0-9]
  42       * 0x2e-0x2f, 0x41-0x5a, 0x61-0x7a, 0x30-0x39
  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 < 0x30) ret += $src - 0x2e + 1; // -45
  52          $ret += (((0x2d - $src) & ($src - 0x30)) >> 8) & ($src - 45);
  53  
  54          // if ($src > 0x40 && $src < 0x5b) ret += $src - 0x41 + 2 + 1; // -62
  55          $ret += (((0x40 - $src) & ($src - 0x5b)) >> 8) & ($src - 62);
  56  
  57          // if ($src > 0x60 && $src < 0x7b) ret += $src - 0x61 + 28 + 1; // -68
  58          $ret += (((0x60 - $src) & ($src - 0x7b)) >> 8) & ($src - 68);
  59  
  60          // if ($src > 0x2f && $src < 0x3a) ret += $src - 0x30 + 54 + 1; // 7
  61          $ret += (((0x2f - $src) & ($src - 0x3a)) >> 8) & ($src + 7);
  62  
  63          return $ret;
  64      }
  65  
  66      /**
  67       * Uses bitwise operators instead of table-lookups to turn 8-bit integers
  68       * into 6-bit integers.
  69       *
  70       * @param int $src
  71       * @return string
  72       */
  73      protected static function encode6Bits(int $src): string
  74      {
  75          $src += 0x2e;
  76  
  77          // if ($src > 0x2f) $src += 0x41 - 0x30; // 17
  78          $src += ((0x2f - $src) >> 8) & 17;
  79  
  80          // if ($src > 0x5a) $src += 0x61 - 0x5b; // 6
  81          $src += ((0x5a - $src) >> 8) & 6;
  82  
  83          // if ($src > 0x7a) $src += 0x30 - 0x7b; // -75
  84          $src -= ((0x7a - $src) >> 8) & 75;
  85  
  86          return \pack('C', $src);
  87      }
  88  }