如何通过加密vb.net windowservice来保护我的连接字符串

Question

如何在app.config中保护我的连接字符串，请任何人建议一个好例子

<configuration>
       <appSettings/>
       <connectionStrings>
  <add name="NorthwindConnectionString" connectionString="Data Source=ARAS02-XP;Initial Catalog=Northwind;User ID=sa"
   providerName="System.Data.SqlClient" />
 </connectionStrings>