Encrypt And Decrypt Connection String In Web.Config File

As you all know the connection string is the pillar of our data. I mean, without a connection string you just can’t create an application which does some database actions like retrieving the data, creating the data, etc. We all know that the connection string is placed in the file called web config. If anyone needs to get the database information of your application, the first place he/she may look at will be the web config file. Am I right? It is always recommended to encrypt the connection string of your application because the data we have there is highly sensitive. It must be secured. Here I am going to show you a demo of how we can do that. You can do the same thing in your Web API project, MVC project, Asp.Net 5 project, or any kind of templates you works with. I hope you will like this.


I used to secure my config file if I am the who starts the project. Here you will get to know how easy the procedure is to encrypt the connection string. There is only a few steps to be followed. I will explain those.


The following is the agenda we are going to follow.

  • Create an empty project, it can be any template (ASP.NET 5, Web API, MVC…)
  • Add a connection string
  • Encrypt the connection string
  • Decrypt the connection string


Create an empty project

To create an empty project, go to File->New->New Project->Name the project->Select Empty->Click OK. Hope you get a solution as follows.

Empty Solution
Figure: Empty Solution

Now We will connect to a database. To connect, please click on the connect icon in your server explorer window and connect you Local/Server database.

Connect to Database
Figure: Connect to Database

Add a connection string

Now it is time to add our connection string, hope you got your data source of the database we already connected. The connection string property must be placed under configuration tag in your web config file. Here is mine.

  1. <connectionStrings>  
  2.    <add name="myConnection" connectionString="Data Source=SIBEESHVENU\SQLEXPRESS;Initial Catalog=ReportServer$SQLEXPRESS;Integrated Security=True" />  
  3. </connectionStrings>   

Now we will create a web page and in the page load event we will fetch this connection string and write it as a response.

  1. using System;  
  2. using System.Collections.Generic;  
  3. using System.Linq;  
  4. using System.Web;  
  5. using System.Web.UI;  
  6. using System.Web.UI.WebControls;  
  7. namespace EncryptConnectionString  
  8. {  
  9.     public partial class Default: System.Web.UI.Page  
  10.     {  
  11.         protected void Page_Load(object sender, EventArgs e)  
  12.         {  
  13.             if (!IsPostBack)  
  14.             {  
  15.                 try  
  16.                 {  
  17.                     string myCon = System.Configuration.ConfigurationManager.ConnectionStrings["myConnection"].ConnectionString;  
  18.                     if (myCon != null)  
  19.                     {  
  20.                         Response.Write("My connection string is :" + myCon);  
  21.                     }  
  22.                 }  
  23.                 catch (Exception)  
  24.                 {  
  25.                     throw;  
  26.                 }  
  27.             }  
  28.         }  
  29.     }  
  30. }   

Please run your page, you will see your connection string in your page.

Connection string response

Connection string response

Encrypt connection string

To start the process, you must open your command window with the admin privilege. Then type the following command.

  1. cd C:\Windows\Microsoft.NET\Framework\v4.0.30319   

This command will narrate you to the framework version folder given. Now right click on your project and click open folder in file explorer and then copy the location. For me it is F:\Visual Studio\EncryptConnectionString\EncryptConnectionString. Now please go back to your command prompt and type the command as follows.

  1. ASPNET_REGIIS -PEF "connectionStrings" "F:\Visual Studio\EncryptConnectionString\EncryptConnectionString"   

Once you click the enter. You will get the output as follows.

Figure: Encrypt ConnectionString Output

Please be noted that the text connectionStrings is case sensitive. If you don’t give it as it is, you will get an error as follows.

  1. C:\Windows\Microsoft.NET\Framework\v4.0.30319>ASPNET_REGIIS -PEF "connectionstrings" "F:\Visual Studio\EncryptConnectionString\EncryptConnectionString"  
  2. Microsoft (R) ASP.NET RegIIS version 4.0.30319.0  
  3. Administration utility to install and uninstall ASP.NET on the local machine.  
  4. Copyright (C) Microsoft Corporation. All rights reserved.  
  5. Encrypting configuration section...  
  6. The configuration section 'connectionstrings' was not found.  
  7. Failed!   

So please be careful while you type the commands. Now I am going back to our application and see the config file. Shall we? You can see the connection string is encrypted as follows.

  1. <connectionStrings configProtectionProvider="RsaProtectedConfigurationProvider">  
  2.     <EncryptedData Type="http://www.w3.org/2001/04/xmlenc#Element" xmlns="http://www.w3.org/2001/04/xmlenc#">  
  3.         <EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#tripledes-cbc" />  
  4.         <KeyInfo xmlns="http://www.w3.org/2000/09/xmldsig#">  
  5.             <EncryptedKey xmlns="http://www.w3.org/2001/04/xmlenc#">  
  6.                 <EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#rsa-1_5" />  
  7.                 <KeyInfo xmlns="http://www.w3.org/2000/09/xmldsig#">  
  8.                     <KeyName>Rsa Key</KeyName>  
  9.                 </KeyInfo>  
  10.                 <CipherData>  
  11.                     <CipherValue>B4B3oZrbpQsYM7Eaq5smukqDj9XUYUCwygBYRG1iasN4ll5W4wAKVCIFCRfvOJGoIXzgqpyjAI30IKf5pnZ/xWqmo3p/wGfOKdMrzd041dt9llLGbxFpLJs0Nkm583PJ1FppXLAy7FOD0YoBVhG/PBtBgLjTQqcXRNbVcgufzuArlv/EH+7lzSNRclXSTMOPMtISF65hPI9ICj9qLx7RBGhVZ6uFZVFteyyuRd2i3D2r7wJfr6KflFkakdxp1OWE2JK4Ldb8kZSwAy3bNaI/qaV9EgIWt9wM6RZO/IrI3kI/bX8JuvirPw3j/+TLDB3MoIgKjSbLpR3GYTm9csPu8g==</CipherValue>  
  12.                 </CipherData>  
  13.             </EncryptedKey>  
  14.         </KeyInfo>  
  15.         <CipherData>  
  16.             <CipherValue>0n1Y6ScSNZDR4x1sXfK05w9h+pp2OrAEQFQsoAUP5Y/hPsfpJS/7jv21PbPlkYmdCzycM4PGGb0+fuffR3RuL1x0tn7rfyUdA9llTfkyRQKwS9xOmkMsVFXgQDr8P4aXGef1fZPE2gjhcjm/JQToLwsfQZK1gNr4d6cIPFNqKD6wt24F7fuySJPX3OgLb8wXfQMd7ij+JcZzNlnyNHbq/DIjxSpPOnMrC52t06Jj8F8+MsSud9GcijcFB2UhvLVXQwyZ51nEj6Tf36Zbca8bgw==</CipherValue>  
  17.         </CipherData>  
  18.     </EncryptedData>  
  19. </connectionStrings>   

Decrypt connection string

You can always decrypt the connection string if you want, to decrypt you just need follows the commands as follows in the command prompt.

  1. cd C:\WINDOWS\Microsoft.NET\Framework\v4.0.30319   

Once after you did you the above command you can execute the preceding one.

  1. ASPNET_REGIIS -PDF "connectionStrings" "F:\Visual Studio\EncryptConnectionString\EncryptConnectionString"  
The text ‘connectionString’ is case sensitive as mentioned above 

If the command is correct, you can get an output as follows.

Decrypting connectionString
Figure: Decrypting connectionString

Now if you check your Web config again, you can see the connection string has got encrypted. Have a happy coding!.


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