xref: /dokuwiki/vendor/paragonie/constant_time_encoding/src/Hex.php (revision 6b69197a9f73c0170a87a2eecfac4f353db0779b) 
1<?php
2declare(strict_types=1);
3namespace ParagonIE\ConstantTime;
4
5use RangeException;
6use TypeError;
7
8/**
9 *  Copyright (c) 2016 - 2022 Paragon Initiative Enterprises.
10 *  Copyright (c) 2014 Steve "Sc00bz" Thomas (steve at tobtu dot com)
11 *
12 *  Permission is hereby granted, free of charge, to any person obtaining a copy
13 *  of this software and associated documentation files (the "Software"), to deal
14 *  in the Software without restriction, including without limitation the rights
15 *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
16 *  copies of the Software, and to permit persons to whom the Software is
17 *  furnished to do so, subject to the following conditions:
18 *
19 *  The above copyright notice and this permission notice shall be included in all
20 *  copies or substantial portions of the Software.
21 *
22 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
23 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
24 *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
25 *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
26 *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
27 *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
28 *  SOFTWARE.
29 */
30
31/**
32 * Class Hex
33 * @package ParagonIE\ConstantTime
34 */
35abstract class Hex implements EncoderInterface
36{
37    /**
38     * Convert a binary string into a hexadecimal string without cache-timing
39     * leaks
40     *
41     * @param string $binString (raw binary)
42     * @return string
43     * @throws TypeError
44     */
45    public static function encode(string $binString): string
46    {
47        $hex = '';
48        $len = Binary::safeStrlen($binString);
49        for ($i = 0; $i < $len; ++$i) {
50            /** @var array<int, int> $chunk */
51            $chunk = \unpack('C', $binString[$i]);
52            $c = $chunk[1] & 0xf;
53            $b = $chunk[1] >> 4;
54
55            $hex .= \pack(
56                'CC',
57                (87 + $b + ((($b - 10) >> 8) & ~38)),
58                (87 + $c + ((($c - 10) >> 8) & ~38))
59            );
60        }
61        return $hex;
62    }
63
64    /**
65     * Convert a binary string into a hexadecimal string without cache-timing
66     * leaks, returning uppercase letters (as per RFC 4648)
67     *
68     * @param string $binString (raw binary)
69     * @return string
70     * @throws TypeError
71     */
72    public static function encodeUpper(string $binString): string
73    {
74        $hex = '';
75        $len = Binary::safeStrlen($binString);
76
77        for ($i = 0; $i < $len; ++$i) {
78            /** @var array<int, int> $chunk */
79            $chunk = \unpack('C', $binString[$i]);
80            $c = $chunk[1] & 0xf;
81            $b = $chunk[1] >> 4;
82
83            $hex .= \pack(
84                'CC',
85                (55 + $b + ((($b - 10) >> 8) & ~6)),
86                (55 + $c + ((($c - 10) >> 8) & ~6))
87            );
88        }
89        return $hex;
90    }
91
92    /**
93     * Convert a hexadecimal string into a binary string without cache-timing
94     * leaks
95     *
96     * @param string $encodedString
97     * @param bool $strictPadding
98     * @return string (raw binary)
99     * @throws RangeException
100     */
101    public static function decode(
102        string $encodedString,
103        bool $strictPadding = false
104    ): string {
105        $hex_pos = 0;
106        $bin = '';
107        $c_acc = 0;
108        $hex_len = Binary::safeStrlen($encodedString);
109        $state = 0;
110        if (($hex_len & 1) !== 0) {
111            if ($strictPadding) {
112                throw new RangeException(
113                    'Expected an even number of hexadecimal characters'
114                );
115            } else {
116                $encodedString = '0' . $encodedString;
117                ++$hex_len;
118            }
119        }
120
121        /** @var array<int, int> $chunk */
122        $chunk = \unpack('C*', $encodedString);
123        while ($hex_pos < $hex_len) {
124            ++$hex_pos;
125            $c = $chunk[$hex_pos];
126            $c_num = $c ^ 48;
127            $c_num0 = ($c_num - 10) >> 8;
128            $c_alpha = ($c & ~32) - 55;
129            $c_alpha0 = (($c_alpha - 10) ^ ($c_alpha - 16)) >> 8;
130
131            if (($c_num0 | $c_alpha0) === 0) {
132                throw new RangeException(
133                    'Expected hexadecimal character'
134                );
135            }
136            $c_val = ($c_num0 & $c_num) | ($c_alpha & $c_alpha0);
137            if ($state === 0) {
138                $c_acc = $c_val * 16;
139            } else {
140                $bin .= \pack('C', $c_acc | $c_val);
141            }
142            $state ^= 1;
143        }
144        return $bin;
145    }
146}
147