encrypt and decrypt query string

This code has been used to encrypt and decrypt query string .No matter what the length of the url is ,this code will encrypt the key and the value the query string into 25 digit

Code:

using System;
using System.Collections.Generic;
using System.Text;
using System.Collections.Specialized;
using System.Collections;
using System.Web;



namespace BusinessLayer
{
    public class QueryString : NameValueCollection
    {
        private string document;
        public string Document
        {
            get
            {
                return document;
            }
        }
        public QueryString()
        {
        }
        public QueryString(NameValueCollection clone)
            : base(clone)
        {

        }

        //this method has been used to get the current URL of the page 
        public static QueryString FromCurrent()
        {
            //returns the current url from the address bar
            return FromUrl (HttpContext.Current.Request.Url.AbsoluteUri) ;
        }

        /// <summary>
        /// This method has been used to divide the Address URl into characters chunks 
        /// </summary>
        /// <param name="url"></param>
        /// <returns></returns>
        public static QueryString FromUrl(string url)
        {
            //it breaks the address URL in array with separator of ? mark
            //this line breaks the Querystring and page 
            string[] parts = url.Split("?".ToCharArray());
            //instantiate the class object
            QueryString qs = new QueryString();
            //assign the page address to the variable
            qs.document = parts[0];
            //if there is any data in array
            if (parts.Length == 1)
                return qs;
            //breaks the QueryString into characters chunks with separator mark &
            string[] keys = parts[1].Split("&".ToCharArray());
            foreach (string key in keys)
            {
                //again breaks into chunks by + mark
                string[] part = key.Split("=".ToCharArray());
                if (part.Length == 1)
                    qs.Add(part[0], "");
                //adds the QueryString key and value pair to the assigned variable
                qs.Add(part[0], part[1]);
            }
            return qs;


        }
        /// <summary>
        /// This method clear all exceptions in the passed string
        /// </summary>
        /// <param name="except"></param>
        public void ClearAllExcept(string except)
        {
            //calls the method to clear except 
            ClearAllExcept(new string[] { except });

        }
        /// <summary>
        /// this is the usual method which has to call clear all exceptions
        /// </summary>
        /// <param name="except"></param>
        public void ClearAllExcept(string[] except)
        {
            //take an arrayList 
            ArrayList toRemove = new ArrayList();
            foreach (string s in this.AllKeys)
            {
                foreach (string e in except)
                {
                    if (s.ToLower() == e.ToLower())
                        if (!toRemove.Contains(s))
                            toRemove.Add(s);

                }
            }
            foreach (string s in toRemove)
                this.Remove(s);
        }
        /// <summary>
        /// this method adds the key value pairs in QueryString of the URL
        /// </summary>
        /// <param name="name"></param>
        /// <param name="value"></param>
        public override void Add(string name, string value)
        {
            //checks nullability of the name 
            if (this[name] != null)
                //if not null then assign value to it
                this[name] = value;

            else

                base.Add(name, value);

        }



        public override string ToString()
        {

            return ToString(false);

        }


        /// <summary>
        /// this ethod has been used to join all the characters array to the URL 
        /// </summary>
        /// <param name="includeUrl"></param>
        /// <returns></returns>
        public string ToString(bool includeUrl)
        {

            string[] parts = new string[this.Count];

            string[] keys = this.AllKeys;
            //for each keys breaks the URL into chunks
            for (int i = 0; i < keys.Length; i++)

                parts[i] = keys[i] + "=" + HttpContext.Current.Server.UrlEncode(this[keys[i]]);

            string url = String.Join("&", parts);

            if ((url != null || url != String.Empty) && !url.StartsWith("?"))

                url = "?" + url;

            if (includeUrl)

                url = this.document + url;

            return url;

        }

    }
}

 

You should have provided an example, which would have used it much easier to understand!