public static void C_DecryptInit(CK_SESSION_HANDLE session, CK_MECHANISM mech, CK_OBJECT_HANDLE key)
 {
     CK_MECHANISM.Native m = new CK_MECHANISM.Native(mech);
     try { CKR_Exception.check(fl.C_DecryptInit(session.Handle, m, key.Handle), "C_DecryptInit"); }
     finally { m.Free(); }
 }