2018/07/31 by Jason L. Pereira, Jason Pereira, Stefano Pirandola · 19 citations
Computer Science · Physics and Astronomy · #Alice (programming language) #Alice and Bob #Channel (broadcasting) #Communication source #Computer network #Computer science #Computer security #Cryptography #Encryption #Key (lock) #Key distribution #Key exchange #Noise (video) #Photon #Physics #Public-key cryptography #Quantum #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum Mechanics and Applications #Quantum cryptography #Quantum information #Quantum key distribution #Quantum mechanics #Side channel attack #Trojan horse #cond-mat.other #physics.ins-det #physics.optics #quant-ph
paper · pdf · doi:10.1103/physreva.98.062319
published in Physical Review A 98(6) (American Physical Society) · 10 pages. 9 figures. Comments are welcome. Typos and a derivation in the conclusions corrected
openalex created_date 2018/07/19 · openalex publication_date 2018/12/17 · arxiv created 2020/10/05 · arxiv updated 2020/10/06 · openalex updated_date 2026/08/05
Security analyses of quantum cryptographic protocols typically rely on certain conditions; one such condition is that the sender (Alice) and receiver (Bob) have isolated devices inaccessible to third parties. If an eavesdropper (Eve) has a side channel in one of the devices, then the key rate may be sensibly reduced. In this paper we consider an attack on a coherent-state protocol, where Eve not only taps the main communication channel but also hacks Alice's device. This is done by introducing a Trojan horse mode with low mean number of photons n, which is then modulated in a similar way to the signal state. First we show that this strategy can be reduced to an attack without side channels but with higher loss and noise in the main channel. Then we show how the key rate rapidly deteriorates for increasing photons n, being halved at long distances each time n+1 doubles. Our work suggests that Alice's device should also be equipped with sensing systems that are able to detect and estimate the total number of incoming and outgoing photons.