function GenerateRandomString(length) {
    var chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmnopqrstuvwxyz";
    var randomstring = '';
    for (var i = 0; i < length; i++) {
        var rnum = Math.floor(Math.random() * chars.length);
        randomstring += chars.substring(rnum, rnum + 1);
    }
   return randomstring;
}

function base64_encode(data) {
    // http://kevin.vanzonneveld.net
    // +   original by: Tyler Akins (http://rumkin.com)
    // +   improved by: Bayron Guevara
    // +   improved by: Thunder.m
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +   bugfixed by: Pellentesque Malesuada
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // -    depends on: utf8_encode
    // *     example 1: base64_encode('Kevin van Zonneveld');
    // *     returns 1: 'S2V2aW4gdmFuIFpvbm5ldmVsZA=='

    // mozilla has this native
    // - but breaks in 2.0.0.12!
    //if (typeof this.window['atob'] == 'function') {
    //    return atob(data);
    //}

    var b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
    var o1, o2, o3, h1, h2, h3, h4, bits, i = 0, ac = 0, enc = "", tmp_arr = [];

    if (!data) {
        return data;
    }

    data = this.utf8_encode(data + '');

    do { // pack three octets into four hexets
        o1 = data.charCodeAt(i++);
        o2 = data.charCodeAt(i++);
        o3 = data.charCodeAt(i++);

        bits = o1 << 16 | o2 << 8 | o3;

        h1 = bits >> 18 & 0x3f;
        h2 = bits >> 12 & 0x3f;
        h3 = bits >> 6 & 0x3f;
        h4 = bits & 0x3f;

        // use hexets to index into b64, and append result to encoded string
        tmp_arr[ac++] = b64.charAt(h1) + b64.charAt(h2) + b64.charAt(h3) + b64.charAt(h4);
    } while (i < data.length);

    enc = tmp_arr.join('');

    switch (data.length % 3) {
        case 1:
            enc = enc.slice(0, -2) + '==';
            break;
        case 2:
            enc = enc.slice(0, -1) + '=';
            break;
    }

    return enc;
}

function base64_decode(data) {
    // http://kevin.vanzonneveld.net
    // +   original by: Tyler Akins (http://rumkin.com)
    // +   improved by: Thunder.m
    // +      input by: Aman Gupta
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +   bugfixed by: Onno Marsman
    // +   bugfixed by: Pellentesque Malesuada
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +      input by: Brett Zamir (http://brett-zamir.me)
    // +   bugfixed by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // -    depends on: utf8_decode
    // *     example 1: base64_decode('S2V2aW4gdmFuIFpvbm5ldmVsZA==');
    // *     returns 1: 'Kevin van Zonneveld'

    // mozilla has this native
    // - but breaks in 2.0.0.12!
    //if (typeof this.window['btoa'] == 'function') {
    //    return btoa(data);
    //}

    var b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
    var o1, o2, o3, h1, h2, h3, h4, bits, i = 0, ac = 0, dec = "", tmp_arr = [];

    if (!data) {
        return data;
    }

    data += '';

    do {  // unpack four hexets into three octets using index points in b64
        h1 = b64.indexOf(data.charAt(i++));
        h2 = b64.indexOf(data.charAt(i++));
        h3 = b64.indexOf(data.charAt(i++));
        h4 = b64.indexOf(data.charAt(i++));

        bits = h1 << 18 | h2 << 12 | h3 << 6 | h4;

        o1 = bits >> 16 & 0xff;
        o2 = bits >> 8 & 0xff;
        o3 = bits & 0xff;

        if (h3 == 64) {
            tmp_arr[ac++] = String.fromCharCode(o1);
        } else if (h4 == 64) {
            tmp_arr[ac++] = String.fromCharCode(o1, o2);
        } else {
            tmp_arr[ac++] = String.fromCharCode(o1, o2, o3);
        }
    } while (i < data.length);

    dec = tmp_arr.join('');
    dec = this.utf8_decode(dec);

    return dec;
}

// private method for UTF-8 encoding
function utf8_encode(string) {
    string = string.replace(/\r\n/g, "\n");
    var utftext = "";

    for (var n = 0; n < string.length; n++) {

        var c = string.charCodeAt(n);

        if (c < 128) {
            utftext += String.fromCharCode(c);
        }
        else if ((c > 127) && (c < 2048)) {
            utftext += String.fromCharCode((c >> 6) | 192);
            utftext += String.fromCharCode((c & 63) | 128);
        }
        else {
            utftext += String.fromCharCode((c >> 12) | 224);
            utftext += String.fromCharCode(((c >> 6) & 63) | 128);
            utftext += String.fromCharCode((c & 63) | 128);
        }

    }

    return utftext;
}

// private method for UTF-8 decoding
function utf8_decode(utftext) {
    var string = "";
    var i = 0;
    var c = c1 = c2 = 0;

    while (i < utftext.length) {

        c = utftext.charCodeAt(i);

        if (c < 128) {
            string += String.fromCharCode(c);
            i++;
        }
        else if ((c > 191) && (c < 224)) {
            c2 = utftext.charCodeAt(i + 1);
            string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
            i += 2;
        }
        else {
            c2 = utftext.charCodeAt(i + 1);
            c3 = utftext.charCodeAt(i + 2);
            string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
            i += 3;
        }

    }

    return string;
}