Attack Strategies on QKD Protocols

Antı́a Lamas-Linares, Qin Liu, Ilja Gerhardt +2 more

Xiang‐Bin Wang

We consider a strategic problem of the Evesdropping to quantum key distribution. Evesdropper hopes to obtain the maxium information given the disturbance to the qubits is often For this strategy, the optimized individual attack have been extensively constructed under various conditions. However, it seems a difficult task in the case of coherent attack, i.e., Eve may treat a number of intercepted qubits collectively, including the collective unitary transformations and the measurements. It was conjectured by Cirac and Gisin that no coherent attack can be more powerful for this strategy for BB84 protocol. In this paper we give a general conclusion on the role of coherent attacks for the strategy of maxmizing the information given the disturbance. Suppose in a quantum key distribution(QKD) protocol, all the transmitted bits from Alice are independent and only the individual disturbances to each qubits are examined by Alice and Bob. For this type of protocols(so far almost all QKD protocols belong to this type), in principle no coherent attack is more powerful than the product of optimized individual attack to each individual qubits. All coherent attacks to the above QKD protocols can be disregarded for the strategy above.

Hicham Amellal, Salma El Hajjami, Keshav Kaushik +2 more

Quantum Key Distribution (QKD) protocols theo- retically propose a high-security level based on the advantages of quantum computing. This paper analyze the security level of one of the most well-known QKD protocols, BB84, against the man-in-the-middle attack strategy. Specifically, we leverage quantum entanglement to enhance communication security by the injection of a malicious photon in the middle of transmission. In the security analysis, we measure the variation in mutual information between the sender-receiver and sender-attacker to assess the protocol's resilience against potential attacks.

Théo Lejeune, François Damanet

Sellami Ali, Khalid A. Saeed Al-Khateeb

Stefan Schauer, MARTIN SUDA

Li et al. presented a protocol [International Journal of Quantum Information4(6) (2006) 899–906] for quantum key distribution based on entanglement swapping. In this protocol, they use random and certain bits to construct a classical key, and they claim that this key is secure. In our article, we show that the protocol by Li et al. is insecure, presenting a new type of attack strategy which gives an adversary full information about the key without being detected. This strategy is based on entanglement swapping, too, and manages to preserve the correlation between the measurement results of the legitimate parties. Further, we present a modified version of the protocol and show that it is secure against this new attack strategy.