if err != nil {
		return nil, nil, err
	}

	return encapsulatedKey, &Sender{
		kem:            kem,
		aead:           aead,
		sharedSecret:   sharedSecret,
		suiteID:        suiteID,
		key:            key,
		baseNonce:      baseNonce,
		exporterSecret: exporterSecret,
	}, nil
}

func (s *Sender) nextNonce() []byte {
	nonce := s.seqNum.bytes()[16-s.aead.NonceSize():]

	go func() {
		wg.Wait()
		defer xioutil.SafeClose(send)
		err := m.handleRequests(ctx, msg, send, handler, handlerIn)
		if err != nil {
			handlerErr.Store(err)
		}
	}()

	// Response sender goroutine...
	go func(outBlock <-chan struct{}) {
		wg.Wait()
		defer m.parent.deleteMux(true, m.ID)
		m.sendResponses(ctx, send, c, &handlerErr, outBlock)
	}(m.outBlock)

	// Remote aliveness check if needed.