Encrypting and Decrypting web.config Information


The most sensitive information stored in web.config file can be the connection string. You do not want to disclose the information related to your database to all the users where the application is deployed. Every time it is not possible to have a private machine for your sites, you may need to deploy the site in shared host environment. In this situation to maintain the security to encrypt and decrypt the web.config file.

We can encrypt the configuration sections by using two built-in providers: DPAPI (Windows Data Protection API) Provider or the RSA provider. The RSA provider (default) uses an RSA key which holds public and private keys, where as the DPAPI provider uses built-in machine-specific key. Let us explore the steps required to encrypt the sections using RSA.

There is two method for encryption and decryption of web.config file.One through asp.net command line and second through programmatically.

Method # 1:

 

Encryption

  ASP.NET 2.0 provides in built functionality to encrypt few sections of web.config file. The task can be completed using Aspnet_regiis.exe. Below is the web.config file and <connectionStrings> section.  

<?xml version="1.0"?><configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0">   <connectionStrings>      <add name="MembershipConnectionString" connectionString="connectionString"/>   </connectionStrings>   <system.web>      <compilation debug="true"/>      <authentication mode="Forms" />   </system.web></configuration>

 In this method for encrypting and decryption of web.config does not involve any code, instead is based on the command line tool aspnet_regiis.This command line tool can be found within the %windows%\Microsoft.NET\Framework\versionNumber folder, or can be run directly from the Visual Studio command prompt.

aspnet_regiis.exe -pef “connectionStrings” C:\Projects\DemoApplication

 

-pef indicates that the application is built as File System website.  The second argument is the name of configuration section needs to be encrypted. Third argument is the physical path where the web.config file is located.If you are using IIS base web site the command will be,

 aspnet_regiis.exe -pe “connectionStrings” -app “/DemoApplication”

.-pe indicates that the application is built as IIS based site. The second argument is the name of configuration section needs to be encrypted. Third argument “-app” indicates virtual directory and last argument is the name of virtual directory where application is deployed.      If everything goes well you will receive a message “Encrypting configuration section…Succeeded!”Open your web.config file and you can see that connection string is encrypted and its look like this.

<?xml version="1.0"?><configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0">   <connectionStrings configProtectionProvider="DataProtectionConfigurationProvider">      <EncryptedData>         <CipherData>            <CipherValue>AQAAANCMnd8BFdERjHoAwE/Cl+sBAAAAed...GicAlQ==</CipherValue>         </CipherData>      </EncryptedData>   </connectionStrings>

   <system.web>      <compilation debug="true"/>      <authentication mode="Forms" />   </system.web></configuration>

Decryption:

Now to decrypt the configuration section in web.config file use following command,For File System Application,

aspnet_regiis.exe -pdf “connectionStrings” C:\Projects\DemoApplication

For IIS based Application

aspnet_regiis.exe -pd “connectionStrings” -app “/DemoApplication”

     If you want to encrypt any nested section in web.config file like <pages> element within <system.web> you need to write full section name as shown below,

aspnet_regiis.exe -pef “system.web/Pages” C:\Projects\DemoApplication

Method # 2:

Step 1: Open Visual Studio > File > WebSite > Select the language (C# or Visual Basic) and location to create a new ASP.NET website.Step 2: Now add a web.config file to the project. Right click the project > Add New Item > Web Configuration FileOpen the web.config and add the following sample entries in the file between the <configuration> tag as shown below:

<configuration>      <appSettings>            <add key="var1" value="SomeValue"/>      </appSettings>      <connectionStrings> <add name="MyConnString" connectionString="Data Source=(local);Initial Catalog=Northwind;Integrated Security=True;" /> </connectionStrings>

      <system.web>...

</configuration>

Step 3: Now add two buttons to the page, called btnEncrypt and btnDecrypt. We will use these buttons to encrypt and decrypt the sections of the web.config file. Add the following code in the button click event of the two buttons:

 

C#

string provider = "RSAProtectedConfigurationProvider";string section = "connectionStrings";

protected void btnEncrypt_Click(object sender, EventArgs e){try{    Configuration confg = WebConfigurationManager.OpenWebConfiguration(Request.ApplicationPath);    ConfigurationSection confStrSect = confg.GetSection(section);    if (confStrSect != null)    {        confStrSect.SectionInformation.ProtectSection(provider);        confg.Save();    }    // the encrypted section is automatically decrypted!!    Response.Write("Configuration Section " + "<b>" +        WebConfigurationManager.ConnectionStrings["MyConnString"].ConnectionString + "</b>" + " is automatically decrypted");}catch (Exception ex){

}        }

protected void btnDecrypt_Click(object sender, EventArgs e){try{    Configuration confg = WebConfigurationManager.OpenWebConfiguration(Request.ApplicationPath);    ConfigurationSection confStrSect = confg.GetSection(section);    if (confStrSect != null && confStrSect.SectionInformation.IsProtected)    {        confStrSect.SectionInformation.UnprotectSection();        confg.Save();    }

}catch (Exception ex){

}}

VB.NET

Private provider As String = "RSAProtectedConfigurationProvider"Private section As String = "connectionStrings"

Protected Sub btnEncrypt_Click(ByVal sender As Object, ByVal e As EventArgs)Try      Dim confg As Configuration = WebConfigurationManager.OpenWebConfiguration(Request.ApplicationPath)      Dim confStrSect As ConfigurationSection = confg.GetSection(section)      If Not confStrSect Is Nothing Then            confStrSect.SectionInformation.ProtectSection(provider)            confg.Save()      End If      ' the encrypted section is automatically decrypted!!      Response.Write("Configuration Section " & "<b>" & WebConfigurationManager.ConnectionStrings("MyConnString").ConnectionString & "</b>" & " is automatically decrypted")Catch ex As Exception

End TryEnd Sub

Protected Sub btnDecrypt_Click(ByVal sender As Object, ByVal e As EventArgs)Try      Dim confg As Configuration = WebConfigurationManager.OpenWebConfiguration(Request.ApplicationPath)      Dim confStrSect As ConfigurationSection = confg.GetSection(section)      If Not confStrSect Is Nothing AndAlso confStrSect.SectionInformation.IsProtected Then            confStrSect.SectionInformation.UnprotectSection()            confg.Save()      End If

Catch ex As Exception

End TryEnd Sub

In the code above, we open the web.config file as a System.Configuration.Configuration object using the specified virtual path. We then call the GetSection() to retrieve the specified ConfigurationSection object, in our case connectionStrings. The ConfigurationSection.SectionInformation property gets us the SectionInformation object, and then we finally call the ProtectSection() method on the SectionInformation object to mark the section for protection.Similarly while decrypting the section, we call the UnprotectSection() method of the SectionInformation object.Step 4: Now run the application and click on the Encrypt button. Now close the application > Open the web.config file. You will observe that the <connectionString> has been encrypted in the following manner:

<connectionStrings configProtectionProvider="RsaProtectedConfigurationProvider"> <EncryptedData Type="http://www.w3.org/2001/04/xmlenc#Element"   xmlns="http://www.w3.org/2001/04/xmlenc#">   <EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#tripledes-cbc" />   <KeyInfo xmlns="http://www.w3.org/2000/09/xmldsig#">    <EncryptedKey xmlns="http://www.w3.org/2001/04/xmlenc#">     <EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#rsa-1_5" />     <KeyInfo xmlns="http://www.w3.org/2000/09/xmldsig#">      <KeyName>Rsa Key</KeyName>     </KeyInfo>     <CipherData>      <CipherValue>ZehN7B+VXBdJTe1X3NFz9Uz3NqxvjSMmbytLeHGNlZa4JkkpRkXzphm5sedHeMTk5KZCHxoYrJ4ssJ0OcZnzLxNUrAB9Ie3y8xJVWJ2s0RQdmaGk5bSJADE1xKJBuOtDIOi/Ron7qJDWXwllC3vvmNwgabmJ9RU+RN35TOQpznc=</CipherValue>     </CipherData>    </EncryptedKey>   </KeyInfo>   <CipherData>    <CipherValue>q2amqNwjeyEbMxF5pZ3XqfboNUJKSml773mPkISGi6uWCWCDPs0ICClmH1eQYcsI9FlxFvEfyRyRRugqOU2xe+gd3aRZEZ5irpGFB45Fn6M+te7kgOeTK1gjGEsbeaNjBNwgpcXMh9RiA9xVOvWlLAyJ3u8DsDQ+4JmM/zTUtxer/8DlUI7+u8D+9V4b5tWxShp4BToMFdTcefhMb19pGdn+jocGetWBJirO5CJsLXI=</CipherValue>   </CipherData> </EncryptedData> </connectionStrings>

Note: If you are running this application from the file system, when you close the application, Visual Studio will display a dialog with the message of “The file has been modified outside the editor. Do you want to reload it?” Click yes and then view the web.config.Step 5: Run the application again and now click on the Decrypt button. You will observe that the <connectionStrings> section is no longer encrypted and can be read as plain text.Note: Take a note that ‘section groups’ like <system.net>, <mailSettings> etc. cannot be encrypted through programmatically .You can encrypt all the sections of web.config file except following using the method I displayed in this article,

<processModel><runtime><mscorlib><startup><system.runtime.remoting><configProtectedData><satelliteassemblies><cryptographySettings><cryptoNameMapping><cryptoClasses>

   To encrypt these section you needed to use Aspnet_setreg.exe tool.

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7 Responses to Encrypting and Decrypting web.config Information

  1. Adnan Badar says:

    >Complete and very useful article for all the developers.Is there any difference between encrypting a app.config rather than web.config?

  2. >No there is no difference app.config in desktop and web.config used in web both you can encrypt and decrypt through same method.

  3. buddy says:

    is it realy secure on production server

  4. Rahul Jain says:

    very usefull thanks

  5. Blogger says:

    Bluehost is ultimately the best web-hosting provider with plans for all of your hosting needs.

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