Covert Message Authentication in MIMO Communications

We propose a novel covert message authentication technique designed to completely obscure the existence of the digital signature, rendering it secure against integrity attacks. This innovative approach not only thwarts counterfeiting attempts of digital signatures but also effectively evades the scrutiny of potential hackers, thereby protecting the authentication scheme proactively. The core idea involves superimposing the digital signature onto the message and harnessing the capabilities of multiple input multiple output (MIMO) techniques to obfuscate the signature. We demonstrate that the total detection error probability (sum of false alarm and miss detection probability) of the signature approaches unity with an increasing number of transmitter antennas, indicating the undetectability of the signature, regardless of its transmission power. Furthermore, we analyze the impact of this covert verification on the signature decoding error probability and the authenticated message throughput, providing insights into the overall effectiveness of the proposed technique in protecting the authenticity of the message. We also investigate how artificial noise affects the total detection error probability and the authenticated message throughput. Finally, we compare two approaches to signature protection: signature secrecy which prevents eavesdroppers from gaining any meaningful information about the signature and signature covertness which hides the signature transmission.