96 lines
3.2 KiB
PHP
96 lines
3.2 KiB
PHP
<?php
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declare(strict_types=1);
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namespace ParagonIE\ConstantTime;
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/**
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* Copyright (c) 2016 - 2018 Paragon Initiative Enterprises.
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* Copyright (c) 2014 Steve "Sc00bz" Thomas (steve at tobtu dot com)
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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/**
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* Class Base64UrlSafe
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* [A-Z][a-z][0-9]\-_
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*
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* @package ParagonIE\ConstantTime
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*/
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abstract class Base64UrlSafe extends Base64
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{
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/**
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* Uses bitwise operators instead of table-lookups to turn 6-bit integers
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* into 8-bit integers.
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*
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* Base64 character set:
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* [A-Z] [a-z] [0-9] - _
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* 0x41-0x5a, 0x61-0x7a, 0x30-0x39, 0x2d, 0x5f
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*
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* @param int $src
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* @return int
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*/
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protected static function decode6Bits(int $src): int
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{
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$ret = -1;
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// if ($src > 0x40 && $src < 0x5b) $ret += $src - 0x41 + 1; // -64
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$ret += (((0x40 - $src) & ($src - 0x5b)) >> 8) & ($src - 64);
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// if ($src > 0x60 && $src < 0x7b) $ret += $src - 0x61 + 26 + 1; // -70
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$ret += (((0x60 - $src) & ($src - 0x7b)) >> 8) & ($src - 70);
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// if ($src > 0x2f && $src < 0x3a) $ret += $src - 0x30 + 52 + 1; // 5
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$ret += (((0x2f - $src) & ($src - 0x3a)) >> 8) & ($src + 5);
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// if ($src == 0x2c) $ret += 62 + 1;
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$ret += (((0x2c - $src) & ($src - 0x2e)) >> 8) & 63;
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// if ($src == 0x5f) ret += 63 + 1;
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$ret += (((0x5e - $src) & ($src - 0x60)) >> 8) & 64;
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return $ret;
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}
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/**
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* Uses bitwise operators instead of table-lookups to turn 8-bit integers
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* into 6-bit integers.
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*
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* @param int $src
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* @return string
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*/
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protected static function encode6Bits(int $src): string
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{
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$diff = 0x41;
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// if ($src > 25) $diff += 0x61 - 0x41 - 26; // 6
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$diff += ((25 - $src) >> 8) & 6;
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// if ($src > 51) $diff += 0x30 - 0x61 - 26; // -75
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$diff -= ((51 - $src) >> 8) & 75;
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// if ($src > 61) $diff += 0x2d - 0x30 - 10; // -13
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$diff -= ((61 - $src) >> 8) & 13;
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// if ($src > 62) $diff += 0x5f - 0x2b - 1; // 3
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$diff += ((62 - $src) >> 8) & 49;
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return \pack('C', $src + $diff);
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}
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}
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