Encrypt and Decrypt URL in MVC 4

Hi,

In the below post we are going to learn about how we can implement a custom URL encryption and decryption logic in MVC 4 .

For encrypt and Decrypt URL in MVC with Area Name click here.

This post will teach you below

1. How to create custom helper
2. How to create custom Attribute and apply them to MVC

So, Lets start from creating custom ActionLinkHelper 

Create a static class “MyExtensions” and  update the code as below.In the below code I have created a custom helper “EncodedActionLink” which will generate the encoded URL

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using System.Text;
using System.Web.Routing;
using System.Security.Cryptography;
using System.IO;

namespace IgnouBuddy.Helpers
{
    public static class MyExtensions
    {                
        public static MvcHtmlString EncodedActionLink(this HtmlHelper htmlHelper, string linkText, string actionName, string controllerName, object routeValues, object htmlAttributes)
        {            
            string queryString = string.Empty;
            string htmlAttributesString = string.Empty;
            if (routeValues != null)
            {
                RouteValueDictionary d = new RouteValueDictionary(routeValues);
                for (int i = 0; i < d.Keys.Count; i++)
                {
                    if (i > 0)
                    {
                        queryString += "?";
                    }
                    queryString += d.Keys.ElementAt(i) + "=" + d.Values.ElementAt(i);
                }
            }

            if (htmlAttributes != null)
            {
                RouteValueDictionary d = new RouteValueDictionary(htmlAttributes);
                for (int i = 0; i < d.Keys.Count; i++)
                {
                    htmlAttributesString += " " + d.Keys.ElementAt(i) + "=" + d.Values.ElementAt(i);                    
                }
            }

            //What is Entity Framework??
            StringBuilder ancor=new StringBuilder();
            ancor.Append("<a ");
            if (htmlAttributesString != string.Empty)
            {
                ancor.Append(htmlAttributesString);
            }
            ancor.Append(" href='");
            if (controllerName != string.Empty)
            {
                ancor.Append("/" + controllerName);
            }

            if (actionName != "Index")
            {
                ancor.Append("/" + actionName);
            }
            if (queryString != string.Empty)
            {
                ancor.Append("?q="+ Encrypt(queryString));
            }
            ancor.Append("'");
            ancor.Append(">");
            ancor.Append(linkText);
            ancor.Append("");
            return new MvcHtmlString(ancor.ToString());
        }

        private static string Encrypt(string plainText)
        {
            string key = "jdsg432387#";
            byte[] EncryptKey = { };
            byte[] IV = { 55, 34, 87, 64, 87, 195, 54, 21 };
            EncryptKey = System.Text.Encoding.UTF8.GetBytes(key.Substring(0, 8));
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            byte[] inputByte = Encoding.UTF8.GetBytes(plainText);
            MemoryStream mStream = new MemoryStream();
            CryptoStream cStream = new CryptoStream(mStream, des.CreateEncryptor(EncryptKey, IV), CryptoStreamMode.Write);
            cStream.Write(inputByte, 0, inputByte.Length);
            cStream.FlushFinalBlock();
            return Convert.ToBase64String(mStream.ToArray());
        }        
    }
}

After updating the code rebuild the project you are ready to render encrypted URL , just you need to call it as regular helper in the views also please add the using directive for your helper in the view page as below

now you can use your helper as below.(using @Html and pressing “.” should show you your custom helper)

@Html.EncodedActionLink(item.QuestionText, "Index", "Answer", new { questionId = item.QuestionID }, null)

Till now first part is done, now get ready for second part .

Create a new class “EncryptedActionParameterAttribute”, inherit it from “ActionFilterAttribute” and update its code as below.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data.Entity;
using System.Data.Entity.Infrastructure;
using System.Threading;
using System.Web.Mvc;
using WebMatrix.WebData;
using IgnouBuddy.Models;
using System.Security.Cryptography;
using System.IO;

namespace IgnouBuddy.Filters
{

    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Method)]
    public class EncryptedActionParameterAttribute : ActionFilterAttribute
    {
        public override void OnActionExecuting(ActionExecutingContext filterContext)
        {

            Dictionary<string, object> decryptedParameters = new Dictionary<string, object>();
            if (HttpContext.Current.Request.QueryString.Get("q") != null)
            {
                string encryptedQueryString = HttpContext.Current.Request.QueryString.Get("q");
                string decrptedString = Decrypt(encryptedQueryString.ToString());
                string[] paramsArrs = decrptedString.Split('?');

                for (int i = 0; i < paramsArrs.Length; i++)
                {
                    string[] paramArr = paramsArrs[i].Split('=');
                    decryptedParameters.Add(paramArr[0], Convert.ToInt32(paramArr[1]));
                }
            }
            for (int i = 0; i < decryptedParameters.Count; i++)
            {
                filterContext.ActionParameters[decryptedParameters.Keys.ElementAt(i)] = decryptedParameters.Values.ElementAt(i);
            }
            base.OnActionExecuting(filterContext);

        }

        private string Decrypt(string encryptedText)
        {
            string key = "jdsg432387#";
            byte[] DecryptKey = { };
            byte[] IV = { 55, 34, 87, 64, 87, 195, 54, 21 };
            byte[] inputByte = new byte[encryptedText.Length];

            DecryptKey = System.Text.Encoding.UTF8.GetBytes(key.Substring(0, 8));
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            inputByte = Convert.FromBase64String(encryptedText);
            MemoryStream ms = new MemoryStream();
            CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(DecryptKey, IV), CryptoStreamMode.Write);
            cs.Write(inputByte, 0, inputByte.Length);
            cs.FlushFinalBlock();
            System.Text.Encoding encoding = System.Text.Encoding.UTF8;
            return encoding.GetString(ms.ToArray());
        }
    }
}

Rebuild the project and now apply the “EncryptedActionParameter” to the actions for which you have generate the encrypted URL.

@Html.EncodedActionLink(item.QuestionText, "Index", "Answer", new { questionId = item.QuestionID }, null)

now run the project and encryption/decryption for URL should work correctly for you.

 

Hope you find this post useful. Thanks for reading .