Trustworthiness of devices in a quantum random number generator based on a symmetric beam splitter
Kejin Wei, Haiqiang Ma, Xiuqing Yang · Journal of the Optical Society of America B · 2017
Quantum random number generators (QRNGs) based on a symmetric beam splitter have attracted a great deal of interest, and the commercial version can be found in the marketplace. However, practical implementations of this QRNG may be imperfect. Here, we propose two attacks for this kind of QRNG, based on some imperfections existing in devices. The first attack exploits the imperfection that the transmission-reflection ratio of a symmetric beam splitter varies with different wavelengths. The second attack can be successful because of the detection efficiency mismatch in two single-photon detectors. With our attacks, Eve can easily break the inherent randomness of the QRNG without being detected. A key point of our paper is to raise awareness of such security loopholes in existing QRNG schemes.