xref: /dokuwiki/vendor/paragonie/constant_time_encoding/src/Base64UrlSafe.php (revision 8e88a29b81301f78509349ab1152bb09c229123e) 
1<?php
2declare(strict_types=1);
3namespace ParagonIE\ConstantTime;
4
5use 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 Base64UrlSafe
32 * [A-Z][a-z][0-9]\-_
33 *
34 * @package ParagonIE\ConstantTime
35 */
36abstract class Base64UrlSafe extends Base64
37{
38
39    /**
40     * Uses bitwise operators instead of table-lookups to turn 6-bit integers
41     * into 8-bit integers.
42     *
43     * Base64 character set:
44     * [A-Z]      [a-z]      [0-9]      -     _
45     * 0x41-0x5a, 0x61-0x7a, 0x30-0x39, 0x2d, 0x5f
46     *
47     * @param int $src
48     * @return int
49     */
50    #[Override]
51    protected static function decode6Bits(int $src): int
52    {
53        $ret = -1;
54
55        // if ($src > 0x40 && $src < 0x5b) $ret += $src - 0x41 + 1; // -64
56        $ret += (((0x40 - $src) & ($src - 0x5b)) >> 8) & ($src - 64);
57
58        // if ($src > 0x60 && $src < 0x7b) $ret += $src - 0x61 + 26 + 1; // -70
59        $ret += (((0x60 - $src) & ($src - 0x7b)) >> 8) & ($src - 70);
60
61        // if ($src > 0x2f && $src < 0x3a) $ret += $src - 0x30 + 52 + 1; // 5
62        $ret += (((0x2f - $src) & ($src - 0x3a)) >> 8) & ($src + 5);
63
64        // if ($src == 0x2c) $ret += 62 + 1;
65        $ret += (((0x2c - $src) & ($src - 0x2e)) >> 8) & 63;
66
67        // if ($src == 0x5f) ret += 63 + 1;
68        $ret += (((0x5e - $src) & ($src - 0x60)) >> 8) & 64;
69
70        return $ret;
71    }
72
73    /**
74     * Uses bitwise operators instead of table-lookups to turn 8-bit integers
75     * into 6-bit integers.
76     *
77     * @param int $src
78     * @return string
79     */
80    #[Override]
81    protected static function encode6Bits(int $src): string
82    {
83        $diff = 0x41;
84
85        // if ($src > 25) $diff += 0x61 - 0x41 - 26; // 6
86        $diff += ((25 - $src) >> 8) & 6;
87
88        // if ($src > 51) $diff += 0x30 - 0x61 - 26; // -75
89        $diff -= ((51 - $src) >> 8) & 75;
90
91        // if ($src > 61) $diff += 0x2d - 0x30 - 10; // -13
92        $diff -= ((61 - $src) >> 8) & 13;
93
94        // if ($src > 62) $diff += 0x5f - 0x2b - 1; // 3
95        $diff += ((62 - $src) >> 8) & 49;
96
97        return \pack('C', $src + $diff);
98    }
99}
100