authenticated using the same key. [...] These stored intermediate values // shall be treated and protected in the same manner as secret keys." marshalableInner, innerOK := h.inner.(marshalable) if !innerOK { return } marshalableOuter, outerOK := h.outer.(marshalable) if !outerOK { return } imarshal, err := marshalableInner.MarshalBinary() if err != nil { return } h.outer.Reset() h.outer.Write(h.opad) omarshal, err := marshalableOuter.MarshalBinary() if err != nil { return } // Marshaling succeeded; save...