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   1  <?php
   2  declare(strict_types=1);
   3  namespace ParagonIE\ConstantTime;
   4  
   5  use Override;
   6  
   7  /**
   8   *  Copyright (c) 2016 - 2022 Paragon Initiative Enterprises.
   9   *  Copyright (c) 2014 Steve "Sc00bz" Thomas (steve at tobtu dot com)
  10   *
  11   *  Permission is hereby granted, free of charge, to any person obtaining a copy
  12   *  of this software and associated documentation files (the "Software"), to deal
  13   *  in the Software without restriction, including without limitation the rights
  14   *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  15   *  copies of the Software, and to permit persons to whom the Software is
  16   *  furnished to do so, subject to the following conditions:
  17   *
  18   *  The above copyright notice and this permission notice shall be included in all
  19   *  copies or substantial portions of the Software.
  20   *
  21   *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  22   *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  23   *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  24   *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  25   *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  26   *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  27   *  SOFTWARE.
  28   */
  29  
  30  /**
  31   * Class Base64DotSlash
  32   * ./[A-Z][a-z][0-9]
  33   *
  34   * @package ParagonIE\ConstantTime
  35   */
  36  abstract class Base64DotSlash extends Base64
  37  {
  38      /**
  39       * Uses bitwise operators instead of table-lookups to turn 6-bit integers
  40       * into 8-bit integers.
  41       *
  42       * Base64 character set:
  43       * ./         [A-Z]      [a-z]     [0-9]
  44       * 0x2e-0x2f, 0x41-0x5a, 0x61-0x7a, 0x30-0x39
  45       *
  46       * @param int $src
  47       * @return int
  48       */
  49      #[Override]
  50      protected static function decode6Bits(int $src): int
  51      {
  52          $ret = -1;
  53  
  54          // if ($src > 0x2d && $src < 0x30) ret += $src - 0x2e + 1; // -45
  55          $ret += (((0x2d - $src) & ($src - 0x30)) >> 8) & ($src - 45);
  56  
  57          // if ($src > 0x40 && $src < 0x5b) ret += $src - 0x41 + 2 + 1; // -62
  58          $ret += (((0x40 - $src) & ($src - 0x5b)) >> 8) & ($src - 62);
  59  
  60          // if ($src > 0x60 && $src < 0x7b) ret += $src - 0x61 + 28 + 1; // -68
  61          $ret += (((0x60 - $src) & ($src - 0x7b)) >> 8) & ($src - 68);
  62  
  63          // if ($src > 0x2f && $src < 0x3a) ret += $src - 0x30 + 54 + 1; // 7
  64          $ret += (((0x2f - $src) & ($src - 0x3a)) >> 8) & ($src + 7);
  65  
  66          return $ret;
  67      }
  68  
  69      /**
  70       * Uses bitwise operators instead of table-lookups to turn 8-bit integers
  71       * into 6-bit integers.
  72       *
  73       * @param int $src
  74       * @return string
  75       */
  76      #[Override]
  77      protected static function encode6Bits(int $src): string
  78      {
  79          $src += 0x2e;
  80  
  81          // if ($src > 0x2f) $src += 0x41 - 0x30; // 17
  82          $src += ((0x2f - $src) >> 8) & 17;
  83  
  84          // if ($src > 0x5a) $src += 0x61 - 0x5b; // 6
  85          $src += ((0x5a - $src) >> 8) & 6;
  86  
  87          // if ($src > 0x7a) $src += 0x30 - 0x7b; // -75
  88          $src -= ((0x7a - $src) >> 8) & 75;
  89  
  90          return \pack('C', $src);
  91      }
  92  }