js base64加密解密

var BASE_64 = function () {
        var hexIn = false;
        var hexOut = false;
        var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
        var base64DecodeChars = new Array(
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
            52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,
            -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
            15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
            -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
            41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1);

        function base64encode(str) {
            var out, i, len;
            var c1, c2, c3;
            var charCode;

            len = str.length;
            i = 0;
            out = "";
            while (i < len) {
                c1 = (hexIn ? str[i++] : str.charCodeAt(i++)) & 0xff;
                if (i == len) {
                    out += base64EncodeChars.charAt(c1 >> 2);
                    out += base64EncodeChars.charAt((c1 & 0x3) << 4);
                    out += "==";
                    break;
                }
                c2 = (hexIn ? str[i++] : str.charCodeAt(i++));
                if (i == len) {
                    out += base64EncodeChars.charAt(c1 >> 2);
                    out += base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4));
                    out += base64EncodeChars.charAt((c2 & 0xF) << 2);
                    out += "=";
                    break;
                }
                c3 = (hexIn ? str[i++] : str.charCodeAt(i++));
                out += base64EncodeChars.charAt(c1 >> 2);
                out += base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4));
                out += base64EncodeChars.charAt(((c2 & 0xF) << 2) | ((c3 & 0xC0) >> 6));
                out += base64EncodeChars.charAt(c3 & 0x3F);
            }
            return out;
        }

        function base64decode(str) {
            var c1, c2, c3, c4;
            var i, len, out;
            var charCode;

            len = str.length;
            i = 0;
            out = hexOut ? [] : "";
            while (i < len) {
                /* c1 */
                do {
                    c1 = base64DecodeChars[str.charCodeAt(i++) & 0xff];
                } while (i < len && c1 == -1);
                if (c1 == -1)
                    break;

                /* c2 */
                do {
                    c2 = base64DecodeChars[str.charCodeAt(i++) & 0xff];
                } while (i < len && c2 == -1);
                if (c2 == -1)
                    break;

                charCode = (c1 << 2) | ((c2 & 0x30) >> 4);
                hexOut ? out.push(charCode) : out += String.fromCharCode(charCode);

                /* c3 */
                do {
                    c3 = str.charCodeAt(i++) & 0xff;
                    if (c3 == 61)
                        return out;
                    c3 = base64DecodeChars[c3];
                } while (i < len && c3 == -1);
                if (c3 == -1)
                    break;
                charCode = ((c2 & 0XF) << 4) | ((c3 & 0x3C) >> 2);
                hexOut ? out.push(charCode) : out += String.fromCharCode(charCode);

                /* c4 */
                do {
                    c4 = str.charCodeAt(i++) & 0xff;
                    if (c4 == 61)
                        return out;
                    c4 = base64DecodeChars[c4];
                } while (i < len && c4 == -1);
                if (c4 == -1)
                    break;
                charCode = ((c3 & 0x03) << 6) | c4;
                hexOut ? out.push(charCode) : out += String.fromCharCode(charCode);
            }
            return out;
        }

        function utf16to8(str) {
            var out, i, len, c;
            var charCode;
            out = hexIn ? [] : "";
            len = str.length;
            for (i = 0; i < len; i++) {
                c = hexIn ? str[i] : str.charCodeAt(i);
                if ((c >= 0x0001) && (c <= 0x007F)) {
                    hexIn ? out.push(str[i]) : out += str.charAt(i);
                } else if (c > 0x07FF) {
                    charCode = (0xE0 | ((c >> 12) & 0x0F));
                    hexIn ? out.push(charCode) : out += String.fromCharCode(charCode);
                    charCode = (0x80 | ((c >> 6) & 0x3F));
                    hexIn ? out.push(charCode) : out += String.fromCharCode(charCode);
                    charCode = (0x80 | ((c >> 0) & 0x3F));
                    hexIn ? out.push(charCode) : out += String.fromCharCode(charCode);
                } else {
                    charCode = (0xC0 | ((c >> 6) & 0x1F));
                    hexIn ? out.push(charCode) : out += String.fromCharCode(charCode);
                    charCode = (0x80 | ((c >> 0) & 0x3F));
                    hexIn ? out.push(charCode) : out += String.fromCharCode(charCode);
                }
            }
            return out;
        }

        function utf8to16(str) {
            var out, i, len, c;
            var char2, char3;
            var charCode;

            out = hexOut ? [] : "";
            len = str.length;
            i = 0;
            while (i < len) {
                c = hexOut ? str[i++] : str.charCodeAt(i++);
                switch (c >> 4) {
                    case 0:
                    case 1:
                    case 2:
                    case 3:
                    case 4:
                    case 5:
                    case 6:
                    case 7:
                        // 0xxxxxxx
                        hexOut ? out.push(str[i - 1]) : out += str.charAt(i - 1);
                        break;
                    case 12:
                    case 13:
                        // 110x xxxx   10xx xxxx
                        char2 = hexOut ? str[i++] : str.charCodeAt(i++);
                        charCode = ((c & 0x1F) << 6) | (char2 & 0x3F);
                        hexOut ? out.push(charCode) : out += String.fromCharCode(charCode);
                        break;
                    case 14:
                        // 1110 xxxx  10xx xxxx  10xx xxxx
                        char2 = hexOut ? str[i++] : str.charCodeAt(i++);
                        char3 = hexOut ? str[i++] : str.charCodeAt(i++);
                        charCode = ((c & 0x0F) << 12) |
                            ((char2 & 0x3F) << 6) |
                            ((char3 & 0x3F) << 0);
                        hexOut ? out.push(charCode) : out += String.fromCharCode(charCode);
                        break;
                }
            }

            return out;
        }

        function CharToHex(str) {
            var out, i, len, c, h;
            out = "";
            len = str.length;
            i = 0;
            while (i < len) {
                c = str.charCodeAt(i++);
                h = c.toString(16);
                if (h.length < 2)
                    h = "0" + h;

                out += "\\x" + h + " ";
                if (i > 0 && i % 8 == 0)
                    out += "\r\n";
            }

            return out;
        }

        function base64_encode(src, hI) {
            if (isEmpty(hI)) hI = false;
            hexIn = hI;
            return base64encode(hexIn ? src : utf16to8(src));
        }

        function base64_decode(src, hO, out_de) {
            if (isEmpty(hO)) hO = false;
            if (isEmpty(out_de)) out_de = 'text';
            hexOut = hO;
            var ret = base64decode(src);
            if (!hexOut || out_de == 'u' || out_de == 'd') {
                ret = utf8to16(ret);
            }
            return ret;
        }

        return {
            base64encode: base64encode,
            base64decode: base64decode,
            utf16to8: utf16to8,
            utf8to16: utf8to16,
            base64_encode: base64_encode,
            base64_decode: base64_decode,
        }
    };