title: Missing System.Security.dll Assembly
body: <p>I was trying to use the System.Security.Cryptography namespace in my Windows Phone 7 project. Of course the "Protect" class wasn't available and I figured that I have to upgrade my 7 app to 7.1.</p>
  
  <p>I did that and still I can't see the class on that namespace. Then I figured I have to reference the System.Security.dll assembly and then it might work. Thing is.. I can't find the assembly</p>
  
  <p>I right-click on the project, select 'Add Reference' and then under the .NET tab there's nothing of the sorts.</p>
  
  <p>Any help?</p>