Stealthy Message Authentication in MIMO Communications

We propose a novel stealthy message authentication technique designed to completely obscure the existence of the digital signature, rendering it secure against integrity attacks. This innovative approach not only prevents digital signature forgery but also evades detection by potential attackers, proactively safeguarding the authentication scheme. 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.