Security is one of the key requirements for the future acceptance of IoT networks. Existing security solutions are based on data encryption using secret keys, which require a trustworthy and complex architecture for their distribution.
As an alternative to conventional key distribution, the encryption keys can be generated using the unique physical layer characteristics of the wireless communication. The radio wave propagation between every “pair” (transmitter and receiver) is unique and reciprocal. Its properties cannot be obtained by a third-party eavesdropper at another location. That is, the signal will suffer many reflections between the transmitter and the receiver. The eavesdropper will also observe the signal, but, since the distances are different, he will experience these reflections differently from the receiver.
Hence, the radio channel is suitable as a random secret source of information to generate and exchange a security key.
This concept is one of the possibilities of what is called Physical Layer Security.