How to get connection string out of Azure KeyVault?

Question

A hypothetical web-site currently connects using:

public SqlConnection CreateConnection()
{
   DbConnection connection = new SqlConnection();
   connection.ConnectionString = GetConnectionString();
   connection.Open();

   return connection;
}

Where the magical connection string is stored in web.config:

String GetConnectionString()
{
   //Get the connection string info from web.config
   ConnectionStringSettings cs = ConfigurationManager.ConnectionStrings["db"];

   if (cs == null)
      throw new Exception("Could not locate DB connection string");

   return cs.ConnectionString;
}

Now i'd like to move the connection string out of the web.config file into Azure KeyVault. How do you retrieve anything out of the Azure key vault?

String GetConnectionString()
{
   //Get the connection string info from Azure KeyVault
   String connectionString = GetAzureSecret("dbConnectionString");

   if (String.IsNullOrWhitespace(connectionString)
      throw new Exception.Create("Could not connection string of Azure Key Vault");

   return connectionString;
}

Except i just made up the easy-to-use Azure API. What is the actual api?

Untested attempt

string GetAzureSecret(string key)
{
    KeyVaultClient vault = new KeyVaultClient();
    vault.OnAuthenticate += VaultClientAuthenticate;

    var sec = await vault.GetSecretAsync(Key);
    return sec.Value;
}

public static async Task<string> VaultClientAuthenticate(string authority, string resource, string scope)
{
   String clientID = "8675209";
   String clientSecret = "correct battery horse pencil";

   var authContext = new AuthenticationContext(authority);
   ClientCredential clientCred = new ClientCredential(clientID, clientSecret);
   AuthenticationResult result = await authContext.AcquireTokenAsync(resource, clientCred);

   if (result == null)
      throw new Exception("Could not acquire token");

   return result.AccessToken;
}

Bonus Reading

• MSDN Forums: Storing sql connection string passwords in Key Vault for my Cloud Services
• How to properly store connection strings in Azure?
• Easily switching ConnectionStrings on publish to Azure

Answer 1

What is the actual api?

We could use the GetSecret API to get value.

Preparation:

Registry Azure Active Directory application and assign Role

Steps:

1.Create KeyVault and add secret from Azure portal

2.Config Access policy

3.Get Access token

 var context = new AuthenticationContext("https://login.windows.net/" + tenantId);
            ClientCredential clientCredential = new ClientCredential(appId, secretKey);
            var tokenResponse =await context.AcquireTokenAsync("https://vault.azure.net", clientCredential);
            var accessToken = tokenResponse.AccessToken;
            return accessToken;

Note: The resource for Keyvault is https://vault.azure.net

4.Test with Fiddler

We also can do that easily with SDK:

1.Create a console project and a Utils.cs file

public static string EncryptSecret { get; set; }
        static string appId = "Application ID";
        static string secretKey = "Secert key";
        static string tenantId = "TenantId";

        public static async Task<string> GetAccessToken(string azureTenantId,string azureAppId,string azureSecretKey)
        {

            var context = new AuthenticationContext("https://login.windows.net/" + tenantId);
            ClientCredential clientCredential = new ClientCredential(appId, secretKey);
            var tokenResponse =await context.AcquireTokenAsync("https://vault.azure.net", clientCredential);
            var accessToken = tokenResponse.AccessToken;
            return accessToken;
        }

2.Add the follow code in the main function and test it.

packages.config file

<?xml version="1.0" encoding="utf-8"?>
<packages>
  <package id="Hyak.Common" version="1.0.2" targetFramework="net452" />
  <package id="Microsoft.Azure.Common" version="2.0.4" targetFramework="net452" />
  <package id="Microsoft.Azure.Common.Dependencies" version="1.0.0" targetFramework="net452" />
  <package id="Microsoft.Azure.KeyVault" version="1.0.0" targetFramework="net452" />
  <package id="Microsoft.Bcl" version="1.1.9" targetFramework="net452" />
  <package id="Microsoft.Bcl.Async" version="1.0.168" targetFramework="net452" />
  <package id="Microsoft.Bcl.Build" version="1.0.14" targetFramework="net452" />
  <package id="Microsoft.IdentityModel.Clients.ActiveDirectory" version="3.13.9" targetFramework="net452" />
  <package id="Microsoft.Net.Http" version="2.2.22" targetFramework="net452" />
  <package id="Newtonsoft.Json" version="6.0.4" targetFramework="net452" />
</packages>

We also can get more information from CtrlDot mentioned document.