While the ambition of QKD technology is to make the key distribution secure even against the most sophisticated physical attacks permitted by quantum theory, an interesting alternative is to consider a restricted class of eavesdropping attacks that can be viewed as imminent with current or near-term technology. When the actual threat takes the form of passive eavesdropping, it is possible to generate a cryprographic key using shot noise properties of the electromagnetic radiation. Here we analyze theoretically the performance of the recently proposed intensity modulation/direct detection protocol for optical key distribution assuming both Gaussian and binary signal modulation.

https://cent.uw.edu.pl/en/person/prof-konrad-banaszek/