<?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);
}
}
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