1<?php
2declare(strict_types=1);
3namespace ParagonIE\ConstantTime;
4
5/**
6 *  Copyright (c) 2016 - 2018 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 Base64DotSlashOrdered
30 * ./[0-9][A-Z][a-z]
31 *
32 * @package ParagonIE\ConstantTime
33 */
34abstract class Base64DotSlashOrdered 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     * [.-9]      [A-Z]      [a-z]
42     * 0x2e-0x39, 0x41-0x5a, 0x61-0x7a
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 < 0x3a) ret += $src - 0x2e + 1; // -45
52        $ret += (((0x2d - $src) & ($src - 0x3a)) >> 8) & ($src - 45);
53
54        // if ($src > 0x40 && $src < 0x5b) ret += $src - 0x41 + 12 + 1; // -52
55        $ret += (((0x40 - $src) & ($src - 0x5b)) >> 8) & ($src - 52);
56
57        // if ($src > 0x60 && $src < 0x7b) ret += $src - 0x61 + 38 + 1; // -58
58        $ret += (((0x60 - $src) & ($src - 0x7b)) >> 8) & ($src - 58);
59
60        return $ret;
61    }
62
63    /**
64     * Uses bitwise operators instead of table-lookups to turn 8-bit integers
65     * into 6-bit integers.
66     *
67     * @param int $src
68     * @return string
69     */
70    protected static function encode6Bits(int $src): string
71    {
72        $src += 0x2e;
73
74        // if ($src > 0x39) $src += 0x41 - 0x3a; // 7
75        $src += ((0x39 - $src) >> 8) & 7;
76
77        // if ($src > 0x5a) $src += 0x61 - 0x5b; // 6
78        $src += ((0x5a - $src) >> 8) & 6;
79
80        return \pack('C', $src);
81    }
82}
83