Remove the encryption from the IAuthenticationService interface. That

is too high up for that type of stuff. It needs to be at the
connector/handler level

OpenSim/Services/AuthenticationService/WebkeyAuthenticationService.cs

@@ -56,10 +56,5 @@ namespace OpenSim.Services.AuthenticationService
         {
             return String.Empty;
         }
-
-        public byte[] AuthenticateEncrypted(byte[] cyphertext, byte[] key)
-        {
-            return new byte[0];
-        }
     }
 }