Time-shift attack in practical quantum cryptosystems
(pp073-082)
Bing Qi, Chi-Hang
F.
Fung, Hoi-Kwong Lo, and
Xiongfeng Ma
doi:
https://doi.org/10.26421/QIC7.1-2-3
Abstracts:
Recently, a new type of attack, which exploits the
efficiency mismatch of two single photon detectors (SPD) in a quantum
key distribution (QKD) system, has been proposed. In this paper, we
propose another ``time-shift'' attack that exploits the same
imperfection. In our attack, Eve shifts the arrival time of either the
signal pulse or the synchronization pulse or both between Alice and Bob.
In particular, in a QKD system where Bob employs time-multiplexing
technique to detect both bit "0'' and bit "1'' with the same SPD, Eve,
in some circumstances, could acquire full information on the final key
without introducing any error. In addition, we prove that if Alice and
Bob are unaware of our attack, the final key they share is insecure. We
emphasize that our attack is simple and feasible with current
technology. Finally, we discuss some counter measures against our and
earlier attacks.
Key words: quantum
cryptography, single photon detector, eavesdropping |