[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 Base32Hex
  30   * [0-9][A-V]
  31   *
  32   * @package ParagonIE\ConstantTime
  33   */
  34  abstract class Base32Hex extends Base32
  35  {
  36      /**
  37       * Uses bitwise operators instead of table-lookups to turn 5-bit integers
  38       * into 8-bit integers.
  39       *
  40       * @param int $src
  41       * @return int
  42       */
  43      protected static function decode5Bits(int $src): int
  44      {
  45          $ret = -1;
  46  
  47          // if ($src > 0x30 && $src < 0x3a) ret += $src - 0x2e + 1; // -47
  48          $ret += (((0x2f - $src) & ($src - 0x3a)) >> 8) & ($src - 47);
  49  
  50          // if ($src > 0x60 && $src < 0x77) ret += $src - 0x61 + 10 + 1; // -86
  51          $ret += (((0x60 - $src) & ($src - 0x77)) >> 8) & ($src - 86);
  52  
  53          return $ret;
  54      }
  55  
  56      /**
  57       * Uses bitwise operators instead of table-lookups to turn 5-bit integers
  58       * into 8-bit integers.
  59       *
  60       * @param int $src
  61       * @return int
  62       */
  63      protected static function decode5BitsUpper(int $src): int
  64      {
  65          $ret = -1;
  66  
  67          // if ($src > 0x30 && $src < 0x3a) ret += $src - 0x2e + 1; // -47
  68          $ret += (((0x2f - $src) & ($src - 0x3a)) >> 8) & ($src - 47);
  69  
  70          // if ($src > 0x40 && $src < 0x57) ret += $src - 0x41 + 10 + 1; // -54
  71          $ret += (((0x40 - $src) & ($src - 0x57)) >> 8) & ($src - 54);
  72  
  73          return $ret;
  74      }
  75  
  76      /**
  77       * Uses bitwise operators instead of table-lookups to turn 8-bit integers
  78       * into 5-bit integers.
  79       *
  80       * @param int $src
  81       * @return string
  82       */
  83      protected static function encode5Bits(int $src): string
  84      {
  85          $src += 0x30;
  86  
  87          // if ($src > 0x39) $src += 0x61 - 0x3a; // 39
  88          $src += ((0x39 - $src) >> 8) & 39;
  89  
  90          return \pack('C', $src);
  91      }
  92  
  93      /**
  94       * Uses bitwise operators instead of table-lookups to turn 8-bit integers
  95       * into 5-bit integers.
  96       *
  97       * Uppercase variant.
  98       *
  99       * @param int $src
 100       * @return string
 101       */
 102      protected static function encode5BitsUpper(int $src): string
 103      {
 104          $src += 0x30;
 105  
 106          // if ($src > 0x39) $src += 0x41 - 0x3a; // 7
 107          $src += ((0x39 - $src) >> 8) & 7;
 108  
 109          return \pack('C', $src);
 110      }
 111  }