The potential of full-duplex in communication design has been recently considered for emerging technologies such as 5G. Moreover, full-duplex can play a crucial role in upcoming secure communication scenarios too. However, results in the literature are limited and only explore scenarios, where the wireless channel is used either for key generation or for secure messaging. Our first contribution is the invention of a deterministic model for full-duplex communication which can analyse both scenarios, depending on the channel gain. Moreover, the properties of the model allow investigating scenarios, which were out of reach before, e.g. mixed channel gain randomness. Furthermore, it can incorporate a recently proposed scheme, called product signalling, which utilizes secure messaging and measures the channel gain bits at the same time. We demonstrate the utility of the model by investigating pilot signalling, i.e. secure key generation and secure messaging, for a two-way wiretap channel model. While pilot signalling is useful for channels with short coherence time, we will see that cooperative jamming is needed for channels with long coherence time. The bit-level nature of our model enables jamming schemes where users can jam individual levels at Eve, in contrast to previous achievable schemes where the users either send messages or jamming signals.