PHP Classes

File: src/Base64UrlSafe.php

Recommend this page to a friend!
  Classes of Scott Arciszewski  >  PHP Constant Time String Encoding  >  src/Base64UrlSafe.php  >  Download  
File: src/Base64UrlSafe.php
Role: Class source
Content type: text/plain
Description: Class source
Class: PHP Constant Time String Encoding
Encode text without leaking context information
Author: By
Last change:
Date: 3 years ago
Size: 3,228 bytes
 

Contents

Class file image Download
<?php
declare(strict_types=1);
namespace
ParagonIE\ConstantTime;

/**
 * Copyright (c) 2016 - 2018 Paragon Initiative Enterprises.
 * Copyright (c) 2014 Steve "Sc00bz" Thomas (steve at tobtu dot com)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

/**
 * Class Base64UrlSafe
 * [A-Z][a-z][0-9]\-_
 *
 * @package ParagonIE\ConstantTime
 */
abstract class Base64UrlSafe extends Base64
{

   
/**
     * Uses bitwise operators instead of table-lookups to turn 6-bit integers
     * into 8-bit integers.
     *
     * Base64 character set:
     * [A-Z] [a-z] [0-9] - _
     * 0x41-0x5a, 0x61-0x7a, 0x30-0x39, 0x2d, 0x5f
     *
     * @param int $src
     * @return int
     */
   
protected static function decode6Bits(int $src): int
   
{
       
$ret = -1;

       
// if ($src > 0x40 && $src < 0x5b) $ret += $src - 0x41 + 1; // -64
       
$ret += (((0x40 - $src) & ($src - 0x5b)) >> 8) & ($src - 64);

       
// if ($src > 0x60 && $src < 0x7b) $ret += $src - 0x61 + 26 + 1; // -70
       
$ret += (((0x60 - $src) & ($src - 0x7b)) >> 8) & ($src - 70);

       
// if ($src > 0x2f && $src < 0x3a) $ret += $src - 0x30 + 52 + 1; // 5
       
$ret += (((0x2f - $src) & ($src - 0x3a)) >> 8) & ($src + 5);

       
// if ($src == 0x2c) $ret += 62 + 1;
       
$ret += (((0x2c - $src) & ($src - 0x2e)) >> 8) & 63;

       
// if ($src == 0x5f) ret += 63 + 1;
       
$ret += (((0x5e - $src) & ($src - 0x60)) >> 8) & 64;

        return
$ret;
    }

   
/**
     * Uses bitwise operators instead of table-lookups to turn 8-bit integers
     * into 6-bit integers.
     *
     * @param int $src
     * @return string
     */
   
protected static function encode6Bits(int $src): string
   
{
       
$diff = 0x41;

       
// if ($src > 25) $diff += 0x61 - 0x41 - 26; // 6
       
$diff += ((25 - $src) >> 8) & 6;

       
// if ($src > 51) $diff += 0x30 - 0x61 - 26; // -75
       
$diff -= ((51 - $src) >> 8) & 75;

       
// if ($src > 61) $diff += 0x2d - 0x30 - 10; // -13
       
$diff -= ((61 - $src) >> 8) & 13;

       
// if ($src > 62) $diff += 0x5f - 0x2b - 1; // 3
       
$diff += ((62 - $src) >> 8) & 49;

        return \
pack('C', $src + $diff);
    }
}

For more information send a message to info at phpclasses dot org.