Encrypt and Decrypt Text in Web API

Mudita Rathore
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Article

Introduction

In this article, I will show you how to encrypt and decrypt text. Here we convert the text into a secret form by encrypting it and convert it back into its original text by decrypting it.

Encrypt : It is process of converting text into a secret form that cannot be readable by other humans. It can only be read by that person that has the encryption key. This is basically used for security.

Decrypt : It is the reverse of encryption. It converts the encrypted text back into its original text. It requires a secret key.

Procedure for creating the application.

Step 1

First we create a Web API application as in the following:

Start Visual Studio 2012.
From the start window select "New Project".
From the new project window select "Installed" -> "Visual C#" -> "Web".
Select "ASP.NET MVC4 Web Application" and click the "OK" button.

From the "MVC4 Project" window select "Web API".

Click the "OK" button.

Step 2

Create a Model class as in the following:

In the "Solution Explorer".
Right-click on the "Model folder" then select "Add" -> "Class".
From the Add Item window select "Installed" -> "Visual C#".

Select Class and click the "Add" button.

Add the following code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
namespace EncriptCode.Models
{
public class EModel
{
public string word { get; set; }
}
}

Step 3

In the "HomeController" write the code to encrypt and decrypt the text. This file exists:

In the "Solution Explorer".
Expand the Controller folder.
Select "HomeController".

Add the following code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using EncriptCode.Models;
using System.Text;
using System.Security.Cryptography;
namespace EncriptCode.Controllers
{
public class HomeController : Controller
{
string key = "1prt56";
public ActionResult Index()
{
EModel obj = new EModel();
return View(obj);
}
[HttpPost]
public ActionResult Index( EModel obj)
{
int req = Convert.ToInt32(Request.Form["type"]);
if (req == 1)
{
ViewBag.Result = Encryptword(obj.word);
}
else
{
ViewBag.Result = Decryptword(obj.word);
}
return View(obj);
}
public string Encryptword(string Encryptval)
{
byte[] SrctArray;
byte[] EnctArray = UTF8Encoding.UTF8.GetBytes(Encryptval);
SrctArray = UTF8Encoding.UTF8.GetBytes(key);
TripleDESCryptoServiceProvider objt = new TripleDESCryptoServiceProvider();
MD5CryptoServiceProvider objcrpt = new MD5CryptoServiceProvider();
SrctArray = objcrpt.ComputeHash(UTF8Encoding.UTF8.GetBytes(key));
objcrpt.Clear();
objt.Key = SrctArray;
objt.Mode = CipherMode.ECB;
objt.Padding = PaddingMode.PKCS7;
ICryptoTransform crptotrns = objt.CreateEncryptor();
byte[] resArray = crptotrns.TransformFinalBlock(EnctArray, 0, EnctArray.Length);
objt.Clear();
return Convert.ToBase64String(resArray, 0, resArray.Length);
}
public string Decryptword(string DecryptText)
{
byte[] SrctArray;
byte[] DrctArray = Convert.FromBase64String(DecryptText);
SrctArray = UTF8Encoding.UTF8.GetBytes(key);
TripleDESCryptoServiceProvider objt = new TripleDESCryptoServiceProvider();
MD5CryptoServiceProvider objmdcript = new MD5CryptoServiceProvider();
SrctArray = objmdcript.ComputeHash(UTF8Encoding.UTF8.GetBytes(key));
objmdcript.Clear();
objt.Key = SrctArray;
objt.Mode = CipherMode.ECB;
objt.Padding = PaddingMode.PKCS7;
ICryptoTransform crptotrns = objt.CreateDecryptor();
byte[] resArray = crptotrns.TransformFinalBlock(DrctArray, 0, DrctArray.Length);
objt.Clear();
return UTF8Encoding.UTF8.GetString(resArray);
}
}
}

UTF8Encoding.UTF8.GetBytes : It encodes the specified string into a specified byte array.

TripleDESCrptoServiceProvider : It provides a wrapper object for accessing the cryptographic service provider version of the TripelDES algorithm. We use the "System.Security.Cryptography" namespace for it.

CipherMode.ECB : CipherMode specifies a block cipher mode for the encryption and the ECB (Electronic Codebook) that encrypts every block individually.

MD5CryptoServiceProvider : It computes the MD5 hash value for the input data using the implementation provided by the cryptographic service provider.

PaddingMode.PKCS7 : Padding is applied when the message data block is shorter than the number of bytes needed for the cryptography. And the PKCS7 padding string consists of a sequence of bytes.

Step 4

Now use the "index.cshtml" file. This file exists: