Encrypt connection string in app.config

Question

I am having trouble encrypting a connection string in app.config. I have code that will protect the connectionStrings section of app.config, but the password is still displayed in plain text.

I need to encrypt the connection string in so it is not in plain text when deployed. I see similiar questions on SO for web.config, but not app.config.

Answer 1

After hours of researching solutions related to the question.

I found a reasonable solution:

The problem with your approach is that your app will need to contain both a decryption key and a decryption algorithm in order to decrypt and use the connection string.

It would be dangerous to assume that even a junior developer won't be able to just debug the code, step through the decryption and get the unencrypted string at the end.

Storing secrets (like connection strings, passwords, API keys) in config files is strongly discouraged as it's a very insecure practice. Instead you should be using a "secrets manager" service -- it's a secure online service that can store your passwords and lets you retrieve them when needed.

When using a secret management service, no secrets or decryption key or algorithm is stored in your source code. Retrieving a secret is as simple as this:

For Azure Key Vault:

 var keyVaultUrl = "https://<your-key-vault-name>.vault.azure.net/";
 var credential =  new DefaultAzureCredential();    
 var client = new SecretClient(vaultUri: new Uri(keyVaultUrl), credential);    
 KeyVaultSecret secret = client.GetSecret("<your-secret-name>");    
 Console.WriteLine($"{secret.Name}: {secret.Value}");

For AWS Secrets Manager (skipped some error handling code):

 var client = new AmazonSecretsManagerClient(accessKeyId, secretAccessKey, 
                                             RegionEndpoint.APSoutheast2);
 var request = new GetSecretValueRequest {
     SecretId = secretName
 };
 GetSecretValueResponse response = null;
 response = client.GetSecretValueAsync(request).Result;

You can also search for an alternative secret manager and implementation like Google Cloud Secret Manager or others.

This approach has lots of advantages over the storage of secrets locally:

• you don't have to mess with storing different values in configs for Prod/Staging/Dev environments -- just read appropriately named secrets (such as '[Dev|Prod|Stag]DBPassword`

• only selected few people can have access to the very important secrets (such as, I dunno, say an authorisation code to transfer all $$$ from Deus account to E-Coin wallets around the world #revolution), and their access can be revoked at any time

• if anyone steals your source code (disgruntled employee, accidental leak) none of your passwords have been leaked

• changing a password is easy -- you just update it using the could management console and restart the app(s)

How to use AWS Secrets Manager to store & read passwords in .Net Core apps

How to securely store and retrieve sensitive info in .NET Core apps with Azure Key Vault

Credits and thanks to @smartial-arts Reference; the second answer.

Answer 2

Additionally, If there is anyone who wants to encrypt and decrypt connection strings in web farms here are the steps:

1. Create an RSA key: aspnet_regiis -pc "MyKeys" -exp

2. Grant access for application pool identity to this key: aspnet_regiis -pa "MyKeys" "IIS AppPool\ApplicationPoolName" -full

3. Add RSA provider to the web.config:

   <configuration>
       <configProtectedData>
           <providers>
               <add name="MyProvider" 
                    type="System.Configuration.RsaProtectedConfigurationProvider, System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL" 
                    keyContainerName="MyKeys" 
                    useMachineContainer="true" />
           </providers>
       </configProtectedData>
   </configuration>
   

4. Encrypt web.config by using the RSA provider: aspnet_regiis -pe "connectionStrings" -app "/MyApplication" -prov "MyProvider" Note: You can use the alternative syntax like the one we did for a single server scenario. Example: ASPNET_REGIIS -pef "connectionStrings" "D:\inetpub\wwwroot\applicationFolder" -prov "MyProvider"

5. Open the web.config and confirm that the connection string is encrypted

6. Test the site and confirm that it is working

7. Try decrypting the web.config. Create a test.aspx file with the code below inside. Browse it to see the decrypted file

8. Export the RSA key to the C drive: aspnet_regiis -px "MyKeys" "c:\keys.xml" -pri

9. Copy this file to the second server in the web farm

10. Import it in that server: aspnet_regiis -pi "MyKeys" "c:\keys.xml"

11. Grant access to this key (same as Step 2)

12. Test the application in the second server

Source: How to encrypt and decrypt connection strings

Answer 3

You can easily apply the same solution as the web.config you just have to rename your app.config to web.config, encrypt with the aspnet_regiis tool and then rename it back to app.config.

1. Rename app.config to web.config
2. Open command prompt and type:
   %windir%\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis -pef "connectionStrings" c:\<folder containing your web.config> (stop at folder level and don't put the trailing "")
3. rename web.config back to app.config

You can open it in notepad to see the encrypted file. In visual studio you will see it's decrypted. You can use your connection string the same way as if it was not encrypted. (Note that it can only be decrypted on the same machine it's encrypted on.)

Answer 4

• Rename App.config file to web.config<br> • Run Command prompt as admin:

For encrypt:

C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis.exe -pef "connectionStrings" your project location within quotes and -prov "DataProtectionConfigurationProvider"

Ex:

C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis.exe -pef "connectionStrings" "D:\location\location1\location" -prov "DataProtectionConfigurationProvider" 

For Decrypt:

C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis.exe -pdf "connectionStrings" your project location within quotes.

Ex:

C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis.exe -pdf "connectionStrings" "D:\location1\location" 

For error:

Add this in Configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0"

Like this:

• Finally, Rename web.config to App.Config

Answer 5

A way to automate this:

ProjectSettings > Compile > BuildEvents > Edit Post-build

Paste the code below:

SET ApplicationName=YourAppWithoutExtention
echo.
echo POST BUILD ACTIONS
echo ====================

if EXIST web.config (
    echo Deleting web.config
    DEL web.config
)

echo Renaming %ApplicationName%.exe.config to web.config
REN %ApplicationName%.exe.config web.config

echo Running aspnet_regis against webconfig
SET rpath=%windir%\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis -pef "connectionStrings" "$(TargetDir)
SET rpath=%rpath:~0,-1%"
echo Path: %rpath%
%rpath%

echo Renaming web.config to %ApplicationName%.exe.config 
REN web.config %ApplicationName%.exe.config

echo Done.

Replacing "YourAppWithoutExtention" with your app name.

Then every time it builds, it will automatically encrypt your app.config.

Answer 6

Define the location of config File

Configuration config  = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);

if you want to encrypt connectionStrings

config.ConnectionStrings.SectionInformation.ProtectSection(Nothing);

you must be aware of app config portions

so if you want to encrypt AppSettings

config.AppSettings.SectionInformation.ProtectSection(Nothing);

Answer 7

Have a look at This Article it has some very useful examples. You're basically looking for System.Configuration.SectionInformation.ProtectSection to help you out here.

Also have a peek at Implementing Protected Configuration