Analysis of coherent quantum cryptography protocol vulnerability to an active beam-splitting attack

Abstract

We consider a new type of attack on a coherent quantum key distribution protocol [coherent one-way (COW) protocol]. The main idea of the attack consists in measuring individually the intercepted states and sending the rest of them unchanged. We have calculated the optimum values of the attack parameters for an arbitrary length of a channel length and compared this novel attack with a standard beam-splitting attack.

Security of the decoy state method for quantum key distribution

“…Note that, in recent works [60][61][62][63], generalizations of the beam splitting attack for the B92, COW, and DPS protocols are considered. In these generalizations, the adversary can change the intensity of states and their further actions depend on whether they has managed to extract information from the part of the state diverted by the beam splitter.…”

Quantum soft filtering for the improved security analysis of the coherent one-way quantum-key-distribution protocol

“…Examples include, in particular, the distributed-phase-reference (DPR) approach [11][12][13][14][15][16][17][18][19], specifically, differential-phase-shift [11][12][13][14][15] and COW [16][17][18][19] QKD protocols. A general security proof of DPR-QKD in a realistic setting has been missing, and only particular cases have been considered [20][21][22][23][24][25][26][27][28]. This problem has been recently generally resolved, and lower bounds for a special variant of the COW protocol have been obtained [29].…”