1<?php
2declare(strict_types=1);
3namespace ParagonIE\ConstantTime;
4
5/**
6 *  Copyright (c) 2016 - 2022 Paragon Initiative Enterprises.
7 *  Copyright (c) 2014 Steve "Sc00bz" Thomas (steve at tobtu dot com)
8 *
9 *  Permission is hereby granted, free of charge, to any person obtaining a copy
10 *  of this software and associated documentation files (the "Software"), to deal
11 *  in the Software without restriction, including without limitation the rights
12 *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
13 *  copies of the Software, and to permit persons to whom the Software is
14 *  furnished to do so, subject to the following conditions:
15 *
16 *  The above copyright notice and this permission notice shall be included in all
17 *  copies or substantial portions of the Software.
18 *
19 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
20 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
21 *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
22 *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
23 *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
24 *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
25 *  SOFTWARE.
26 */
27
28/**
29 * Class Base64DotSlash
30 * ./[A-Z][a-z][0-9]
31 *
32 * @package ParagonIE\ConstantTime
33 */
34abstract class Base64DotSlash extends Base64
35{
36    /**
37     * Uses bitwise operators instead of table-lookups to turn 6-bit integers
38     * into 8-bit integers.
39     *
40     * Base64 character set:
41     * ./         [A-Z]      [a-z]     [0-9]
42     * 0x2e-0x2f, 0x41-0x5a, 0x61-0x7a, 0x30-0x39
43     *
44     * @param int $src
45     * @return int
46     */
47    protected static function decode6Bits(int $src): int
48    {
49        $ret = -1;
50
51        // if ($src > 0x2d && $src < 0x30) ret += $src - 0x2e + 1; // -45
52        $ret += (((0x2d - $src) & ($src - 0x30)) >> 8) & ($src - 45);
53
54        // if ($src > 0x40 && $src < 0x5b) ret += $src - 0x41 + 2 + 1; // -62
55        $ret += (((0x40 - $src) & ($src - 0x5b)) >> 8) & ($src - 62);
56
57        // if ($src > 0x60 && $src < 0x7b) ret += $src - 0x61 + 28 + 1; // -68
58        $ret += (((0x60 - $src) & ($src - 0x7b)) >> 8) & ($src - 68);
59
60        // if ($src > 0x2f && $src < 0x3a) ret += $src - 0x30 + 54 + 1; // 7
61        $ret += (((0x2f - $src) & ($src - 0x3a)) >> 8) & ($src + 7);
62
63        return $ret;
64    }
65
66    /**
67     * Uses bitwise operators instead of table-lookups to turn 8-bit integers
68     * into 6-bit integers.
69     *
70     * @param int $src
71     * @return string
72     */
73    protected static function encode6Bits(int $src): string
74    {
75        $src += 0x2e;
76
77        // if ($src > 0x2f) $src += 0x41 - 0x30; // 17
78        $src += ((0x2f - $src) >> 8) & 17;
79
80        // if ($src > 0x5a) $src += 0x61 - 0x5b; // 6
81        $src += ((0x5a - $src) >> 8) & 6;
82
83        // if ($src > 0x7a) $src += 0x30 - 0x7b; // -75
84        $src -= ((0x7a - $src) >> 8) & 75;
85
86        return \pack('C', $src);
87    }
88}
89