title: Generate SHA1 Hash in Portable Class Library
body: <p>I'm trying to build a portable class library that generates OAuth urls for other classes/applications to use. This class library using OAuth has to be a portable class library so it can work with different versions of a DropBox API I'm building.</p>
  
  <p>Part of this class needs to generate an SHA1 hash to generate the oauth_signature with.</p>
  
  <p>I'm aware that portable class library doesn't support System.Security.Cryptography, so is there anyway that this class can generate an SHA1 hash without that class?</p>