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LittleBeast / src / Std / Lib / BaseN.php
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1<?php
2/*************************************************************
3# 076 License
4
5Copyright (c) テクニカル諏訪子
6
7Permission is hereby granted to any person obtaining a copy of the software
8Little Beast (the "Software") to use, modify, merge, copy, publish, distribute,
9sublicense, and/or sell copies of the Software, subject to the following conditions:
10
11 1. **Origin Attribution**:
12 - You must not misrepresent the origin of the Software; you must not claim
13 you created the original Software.
14 - If the Software is used in a product, you must either:
15 a. Provide clear attribution in the product's documentation, user interface,
16 or other visible areas, **OR**
17 b. Pay the original developers a fee they specify in writing.
18 2. **Usage Restriction**:
19 - The Software, or any derivative works, dependencies, or libraries
20 incorporating it, must not be used for censorship or to suppress freedom of
21 speech, expression, or creativity. Prohibited uses include, but are not
22 limited to:
23 - Censorship of so-called "hate speech", visuals, non-mainstream opinions,
24 ideas, or objective reality.
25 - Tools or systems designed to restrict access to information or
26 artistic works.
27 3. **Notice Preservation**:
28 - This license and the above copyright notice must remain intact in all copies
29 of the source code.
30
31THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
32INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
33PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
34HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
35CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
36OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
37 */
38namespace Std\Lib;
39
40/**
41 * Base32とBase64（RFC 4648）
42 *
43 * Base32は二段階認証の秘密鍵（大文字・小文字、空白、ハイフン、パディングの有無は問わずに読む）、
44 * Base64はURL用の変種（「-」と「_」）も使える。
45 */
46final class BaseN {
47 private const B32 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567';
48 private const B64 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
49 private const B64URL = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_';
50
51 public static function encode32(string $data, bool $pad = true): string {
52 return self::encode($data, self::B32, 5, $pad ? 8 : 1);
53 }
54
55 /**
56 * @throws \InvalidArgumentException Base32ではない文字、又は有り得ない長さ
57 */
58 public static function decode32(string $text): string {
59 $text = rtrim(strtoupper(str_replace([' ', '-', "\t", "\r", "\n"], '', $text)), '=');
60 // 8文字（40ビット）の内、1・3・6文字で終わる事は無い
61 if (in_array(strlen($text) % 8, [1, 3, 6], true)) throw new \InvalidArgumentException('Base32の長さが不正です。');
62 return self::decode($text, self::B32, 5);
63 }
64
65 /**
66 * @param bool $url URL用（「+/」の代わりに「-_」）
67 */
68 public static function encode64(string $data, bool $url = false, bool $pad = true): string {
69 return self::encode($data, $url ? self::B64URL : self::B64, 6, $pad ? 4 : 1);
70 }
71
72 /**
73 * @throws \InvalidArgumentException Base64ではない文字、又は有り得ない長さ
74 */
75 public static function decode64(string $text, bool $url = false): string {
76 $text = rtrim(str_replace([' ', "\t", "\r", "\n"], '', $text), '=');
77 if (strlen($text) % 4 === 1) throw new \InvalidArgumentException('Base64の長さが不正です。');
78 return self::decode($text, $url ? self::B64URL : self::B64, 6);
79 }
80
81 /**
82 * @param int $bits 1文字のビット数
83 * @param int $block パディングで揃える文字数（1なら付けない）
84 */
85 private static function encode(string $data, string $alphabet, int $bits, int $block): string {
86 $out = '';
87 $acc = 0;
88 $n = 0;
89 $mask = (1 << $bits) - 1;
90 for ($i = 0, $len = strlen($data); $i < $len; $i++) {
91 $acc = (($acc << 8) | ord($data[$i])) & 0xffff;
92 $n += 8;
93 while ($n >= $bits) {
94 $n -= $bits;
95 $out .= $alphabet[($acc >> $n) & $mask];
96 }
97 }
98 if ($n > 0) $out .= $alphabet[($acc << ($bits - $n)) & $mask];
99 $rest = strlen($out) % $block;
100 return $rest ? $out.str_repeat('=', $block - $rest) : $out;
101 }
102
103 private static function decode(string $text, string $alphabet, int $bits): string {
104 $out = '';
105 $acc = 0;
106 $n = 0;
107 for ($i = 0, $len = strlen($text); $i < $len; $i++) {
108 $v = strpos($alphabet, $text[$i]);
109 if ($v === false) throw new \InvalidArgumentException('不正な文字があります。');
110 $acc = (($acc << $bits) | $v) & 0xffff;
111 $n += $bits;
112 if ($n >= 8) {
113 $n -= 8;
114 $out .= chr(($acc >> $n) & 0xff);
115 }
116 }
117 return $out;
118 }
119}