title: Missing System.Security.Cryptography
body: <p>I want to use the <code>HMACSHA1</code> class in a project but the namespace <code>System.Security.Cryptography</code> is missing. If I add the reference <code>System.Security</code>, I find the namespace <code>Cryptography</code> but without the class <code>HMACSHA1</code>. And I can't find the namespace <code>Windows.Security.Cryptography</code> which seems to replace <code>System.Security.Cryptography</code>.</p>
  
  <p>My projet targets the framework <code>.NET 4.5</code>and the <code>.NET</code> for Windows Store apps and He use <code>Nuget</code> on <code>Visual 2012</code> on <code>Windows 7</code>.</p>
  
  <p>Someone have a solution to this problem ?</p>