reversing vPass2

gistfile1.js

encrypt = function(data, length) {
  var chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789$%,()*-./;:<=>?[\]^_{|}~".split("");
	var chars_length = chars.length;
	var data_length = data.length;

	// Data is required
	if(data == "") {
		return "";
	}

	// Default value for length
	length = length || data_length;

	// Calculate the offset of the first character.
	for(var last = 0, i = 0; i < data_length; i++) {
		last = (data.charCodeAt(i) + 31 * last) % 59;
	}

	// Grow data if it's shorter than required length
	while(data_length < length) {
		data += data;
		data_length += data_length;
	}
	data = data.slice(0, length);

    //last = 0;

	// Generate the encrypted string.
	for(var ret = "", i = 0; i < length; i++) {
		ret += chars[last = (i + last + data.charCodeAt(i)) % chars_length];
	}
	return ret;
};

decrypt = function(data, length) {
	var chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789$%,()*-./;:<=>?[\]^_{|}~";
	var chars_length = chars.length;
	var data_length = data.length;

    var tab = {};
    for (var i = 0; i < chars_length; i++) {
        tab[chars.charCodeAt(i)] = i;
    }

	// Data is required
	if(data == "") {
		return "";
	}

	// Default value for length
	length = length || data_length;

	// Calculate the offset of the first character.
	for(var last = 0, i = 0; i < data_length; i++) {
		last = (data.charCodeAt(i) + 31 * last) % 59;
	}


	// Grow data if it's shorter than required length
	while(data_length < length) {
		data += data;
		data_length += data_length;
	}
	data = data.slice(0, length);

    var res = [];
    for (var j = 0; j < 59; j++) {
        prev = j;
        // Generate the encrypted string.
        for(var ret = "", i = 0; i < data_length; i++) {
            var cur = tab[data.charCodeAt(i)];
            ch = (cur + 85) - prev - i;
            prev = cur;
            //console.log(data[i], prev, ch);
            if (ch < 65) ch += 85;
            ret += String.fromCharCode(ch);
        }
        res.push(ret);
    }
    return res;
};

console.log(encrypt("insecure", 10));
console.log(decrypt("o)NgyCl8Dl", 10));