c# - ASP.NET Encryption - aspnet_regiis - Farm

Question

We have website that uses "NT AuthorityNetwork Service".

Response.Write(WindowsIdentity.GetCurrent().Name); 

We are currently using the following command to encrypt the config files.

aspnet_regiis -pc "NetFrameworkConfigurationKey"
aspnet_regiis -pa "NetFrameworkConfigurationKey" "NT AuthorityNetwork Service"
aspnet_regiis.exe -pef "connectionStrings" "C:WebAppLocationFolder"

Note: We are not using "-exp". When we use "-exp" it is not creating RSA Key Container.

AS you can see, we are using the default key- NetFrameworkConfigurationKey. Our website has a load balancer. Webserver1(W1) and WebServer2 (W2) are available.

If I follow the above mentioned commands, we will be using separate keys on W1 and W2. However the website works with this approach.

Is this approach sufficient? Does it got any shortcomings or secuirty holes? Will it fail in any scenario?

Note: Machine key is added in our web.config. It is same in both config. However, our configProtectedData is not in the Web.Config. Also,I think, NetFrameworkConfigurationKey will be different in both the servers.

I have read the following msdn aricle for Encryption in Web Farm Scenarios. http://msdn.microsoft.com/en-us/library/ff650304.aspx

Answer 1

I doesn't sound to me like you've done everything correctly. First of all, there's two issues here:

1. Ensuring the machineKey is the same on both web servers.
2. Ensuring the same RSA private key is installed in a key container on both servers so that the encrypted configuration can be decrypted by each server.

These are separate concerns: the machineKey isn't relevant for encrypting/decrypting the config section you want to protect.

So first of all the aspnet_regiis -pc command is used to create a new RSA key container and the reason it's failing is that the container name you've specified already exists because it's the default. The keypair in this container is not exportable so you need to create a new key container and specify the -exp switch to denote that the keypair is exportable.

aspnet_regiis -pc "MyDeploymentKeyContainer" -exp

Then export the key to a file, including the private key: the private key is used to decrypt the config section so the web server will need it.

aspnet_regiis -px "MyDeploymentKeyContainer" deploykey.xml -pri

Now add the config section to your web.config and save it.

<configProtectedData>
  <providers>
  <add keyContainerName="MyDeploymentKeyContainer" 
           useMachineContainer="true"
           description="Uses RsaCryptoServiceProvider to encrypt and decrypt"
           name="DeploymentProvider"
     type="System.Configuration.RsaProtectedConfigurationProvider,System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
  </providers>
</configProtectedData>

Then encrypt the web.config section specifying the provider name as shown above (here it is "DeploymentProvider")

aspnet_regiis -pef "connectionStrings" "C:WebAppLocationFolder" -prov "DeploymentProvider"

Now you need to deploy the app to both servers and import the RSA key container you exported to the file earlier. Copy the file up and on each server run:

aspnet_regiis -pi deploykey.xml

Once that's done delete the file from the server - you don't want it hanging about. Finally grant the user account for the app pool running your web app access to the key container on both web servers.

aspnet_regiis -pa "MyDeploymentKeyContainer" SomeDomainSomeAccount