On secret key generation with massive MIMO antennas using time-frequency-space dimensions

Kerchoff's principle states that the security of encryption should be based on the key. Thus, increasing the encryption key length has been an essential approach in generating unbreakable ciphers. Recently, physical layer security has gained significant research attention. It allows secure communications between a source and destination without the need to resort to key-based encryption techniques. In this paper, secret key generation using massive multiple input multiple output (MIMO) techniques is investigated. The large number of subcarriers used in orthogonal frequency division multiple access (OFDMA) systems is also used to increase the key length. Several scenarios are investigated and corresponding key lengths are calculated. The combination of massive MIMO and OFDMA also allows to simultaneously implement physical layer security techniques while generating large keys for traditional key-based cryptography.