-type key() ::
          #'ECPrivateKey'{version :: term(),
                          privateKey :: term(),
                          parameters :: term(),
                          publicKey :: term(),
                          attributes :: term()} |
          {#'ECPoint'{point :: term()},
           {namedCurve, Oid :: tuple()} |
           #'ECParameters'{version :: term(),
                           fieldID :: term(),
                           curve :: term(),
                           base :: term(),
                           order :: term(),
                           cofactor :: term()}}.