"use strict"; /*jslint bitwise: false */ function encode64(s) { // the result/encrypted string, the padding string, and the pad count var r = "", p = "", c = s.length % 3, n, chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'.split(""); // add a right zero pad to make this string a multiple of 3 characters if (c > 0) { for (; c < 3; c++) { p += '='; s += String.fromCharCode(0); } } // increment over the length of the string, three characters at a time for (c = 0; c < s.length; c += 3) { // we add newlines after every 76 output characters, according to // the MIME specs if (c > 0 && (c / 3 * 4) % 76 === 0) { r += "\r\n"; } // these three 8-bit (ASCII) characters become one 24-bit number n = (s.charCodeAt(c) << 16) + (s.charCodeAt(c + 1) << 8) + s.charCodeAt(c + 2); // this 24-bit number gets separated into four 6-bit numbers n = [(n >>> 18) & 63, (n >>> 12) & 63, (n >>> 6) & 63, n & 63]; // those four 6-bit numbers are used as indices into the // base64 character list r += chars[n[0]] + chars[n[1]] + chars[n[2]] + chars[n[3]]; } // add the actual padding string, after removing the zero pad return r.substring(0, r.length - p.length) + p; }