https://oauth2.gn-online.de/sso/src/base64url-arraybuffer.js

1/*
2 * Base64URL-ArrayBuffer
3 * https://github.com/herrjemand/Base64URL-ArrayBuffer
4 *
5 * Copyright (c) 2017 Yuriy Ackermann <[email protected]>
6 * Copyright (c) 2012 Niklas von Hertzen
7 * Licensed under the MIT license.
8 * 
9 */
10(function(){
11    "use strict";
12
13    var chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
14
15    // Use a lookup table to find the index.
16    var lookup = new Uint8Array(256);
17    for (var i = 0; i < chars.length; i++) {
18        lookup[chars.charCodeAt(i)] = i;
19    }
20
21    var encode = function(arraybuffer) {
22        var bytes = new Uint8Array(arraybuffer),
23        i, len = bytes.length, base64 = "";
24
25        for (i = 0; i < len; i+=3) {
26            base64 += chars[bytes[i] >> 2];
27            base64 += chars[((bytes[i] & 3) << 4) | (bytes[i + 1] >> 4)];
28            base64 += chars[((bytes[i + 1] & 15) << 2) | (bytes[i + 2] >> 6)];
29            base64 += chars[bytes[i + 2] & 63];
30        }
31
32        if ((len % 3) === 2) {
33            base64 = base64.substring(0, base64.length - 1);
34        } else if (len % 3 === 1) {
35            base64 = base64.substring(0, base64.length - 2);
36        }
37
38        return base64;
39    };
40
41    var decode = function(base64) {
42        var bufferLength = base64.length * 0.75,
43        len = base64.length, i, p = 0,
44        encoded1, encoded2, encoded3, encoded4;
45
46        var arraybuffer = new ArrayBuffer(bufferLength),
47        bytes = new Uint8Array(arraybuffer);
48
49        for (i = 0; i < len; i+=4) {
50            encoded1 = lookup[base64.charCodeAt(i)];
51            encoded2 = lookup[base64.charCodeAt(i+1)];
52            encoded3 = lookup[base64.charCodeAt(i+2)];
53            encoded4 = lookup[base64.charCodeAt(i+3)];
54
55            bytes[p++] = (encoded1 << 2) | (encoded2 >> 4);
56            bytes[p++] = ((encoded2 & 15) << 4) | (encoded3 >> 2);
57            bytes[p++] = ((encoded3 & 3) << 6) | (encoded4 & 63);
58        }
59
60        return arraybuffer;
61    };
62
63     /**
64     * Exporting and stuff
65     */
66    if (typeof module !== 'undefined' && typeof module.exports !== 'undefined') {
67        module.exports = {
68            'encode': encode,
69            'decode': decode
70        }
71
72    } else {
73        if (typeof define === 'function' && define.amd) {
74            define([], function() {
75                return {
76                    'encode': encode,
77                    'decode': decode
78                }
79            });
80        } else {
81            window.base64url = {
82                'encode': encode,
83                'decode': decode
84            }
85        }
86    }
87})();