xref: /dokuwiki/vendor/paragonie/constant_time_encoding/src/Base64DotSlash.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 Base64DotSlash
32 * ./[A-Z][a-z][0-9]
33 *
34 * @package ParagonIE\ConstantTime
35 */
36abstract class Base64DotSlash extends Base64
37{
38    /**
39     * Uses bitwise operators instead of table-lookups to turn 6-bit integers
40     * into 8-bit integers.
41     *
42     * Base64 character set:
43     * ./         [A-Z]      [a-z]     [0-9]
44     * 0x2e-0x2f, 0x41-0x5a, 0x61-0x7a, 0x30-0x39
45     *
46     * @param int $src
47     * @return int
48     */
49    #[Override]
50    protected static function decode6Bits(int $src): int
51    {
52        $ret = -1;
53
54        // if ($src > 0x2d && $src < 0x30) ret += $src - 0x2e + 1; // -45
55        $ret += (((0x2d - $src) & ($src - 0x30)) >> 8) & ($src - 45);
56
57        // if ($src > 0x40 && $src < 0x5b) ret += $src - 0x41 + 2 + 1; // -62
58        $ret += (((0x40 - $src) & ($src - 0x5b)) >> 8) & ($src - 62);
59
60        // if ($src > 0x60 && $src < 0x7b) ret += $src - 0x61 + 28 + 1; // -68
61        $ret += (((0x60 - $src) & ($src - 0x7b)) >> 8) & ($src - 68);
62
63        // if ($src > 0x2f && $src < 0x3a) ret += $src - 0x30 + 54 + 1; // 7
64        $ret += (((0x2f - $src) & ($src - 0x3a)) >> 8) & ($src + 7);
65
66        return $ret;
67    }
68
69    /**
70     * Uses bitwise operators instead of table-lookups to turn 8-bit integers
71     * into 6-bit integers.
72     *
73     * @param int $src
74     * @return string
75     */
76    #[Override]
77    protected static function encode6Bits(int $src): string
78    {
79        $src += 0x2e;
80
81        // if ($src > 0x2f) $src += 0x41 - 0x30; // 17
82        $src += ((0x2f - $src) >> 8) & 17;
83
84        // if ($src > 0x5a) $src += 0x61 - 0x5b; // 6
85        $src += ((0x5a - $src) >> 8) & 6;
86
87        // if ($src > 0x7a) $src += 0x30 - 0x7b; // -75
88        $src -= ((0x7a - $src) >> 8) & 75;
89
90        return \pack('C', $src);
91    }
92}
93