function base64_decode(str){
    var c1, c2, c3, c4;
    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
    );
    var i=0, len = str.length, string = '';

    while (i < len){
            do{
                    c1 = base64DecodeChars[str.charCodeAt(i++) & 0xff]
            } while (
                    i < len && c1 == -1
            );

            if (c1 == -1) break;

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

            if (c2 == -1) break;

            string += String.fromCharCode((c1 << 2) | ((c2 & 0x30) >> 4));

            do{
                    c3 = str.charCodeAt(i++) & 0xff;
                    if (c3 == 61)
                            return string;

                    c3 = base64DecodeChars[c3]
            } while (
                    i < len && c3 == -1
            );

            if (c3 == -1) break;

            string += String.fromCharCode(((c2 & 0XF) << 4) | ((c3 & 0x3C) >> 2));

            do{
                    c4 = str.charCodeAt(i++) & 0xff;
                    if (c4 == 61) return string;
                    c4 = base64DecodeChars[c4]
            } while (
                    i < len && c4 == -1
            );

            if (c4 == -1) break;

            string += String.fromCharCode(((c3 & 0x03) << 6) | c4)
    }
    return string;
}

function base64_encode(str){
    var c1, c2, c3;
    var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";               
    var i = 0, len= str.length, string = '';

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