Success of any eavesdropping attack on a quantum cryptographic protocol can be reduced by the legitime users if they partially compare their data. It is important to know for the legitime users what is (necessary and enough) amount of data which should be compared to ensure that (possible) illegitime user has an arbitrary small information about the rest of data. To obtain such amount the legitime users need to know efficiencies of all possible attacks for particular cryptographic protocol. In this work we introduce the eavesdropping attack on Bennett’s B92 protocol for quantum key distribution (QKD) with a quantum cloning machine (QCM). We demonstrate efficiency of suggested attack and compare it with efficiencies of alternative attacks proposed before.
Success of any eavesdropping attack on a quantum cryptographic protocol can be reduced by the legitime users if they partially compare their data. It is important to know for the legitime users what is (necessary and enough) amount of data which should be compared to ensure that (possible) illegitime user has an arbitrary small information about the rest of data. To obtain such amount the legitime users need to know efficiencies of all possible attacks for particular cryptographic protocol. In this work we introduce the eavesdropping attack on Bennett’s B92 protocol for quantum key distribution (QKD) with a quantum cloning machine (QCM). We demonstrate efficiency of suggested attack and compare it with efficiencies of alternative attacks proposed before.
The security of quantum cryptography is guaranteed by the no-cloning theorem, which implies that an eavesdropper copying transmitted qubits in unknown states causes their disturbance. Nevertheless, in real cryptographic systems some level of disturbance has to be allowed to cover, e.g., transmission losses. An eavesdropper can attack such systems by replacing a noisy channel by a better one and by performing approximate cloning of transmitted qubits which disturb them but below the noise level assumed by legitimate users. We experimentally demonstrate such symmetric individual eavesdropping on the quantum key distribution protocols of Bennett and Brassard (BB84) and the trine-state spherical code of Renes (R04) with two-level probes prepared using a recently developed photonic multifunctional quantum cloner [Lemr et al., Phys. Rev. A 85, 050307(R) (2012)]. We demonstrated that our optimal cloning device with high-success rate makes the eavesdropping possible by hiding it in usual transmission losses. We believe that this experiment can stimulate the quest for other operational applications of quantum cloning.
An attempt to eavesdrop on a quantum cryptographic channel reveals itself through errors it inevitably introduces into the transmission. We investigate the relationship between the induced error rate and the maximum amount of information the eavesdropper can extract, in both the two-state B92 [B92 refers to the work of C. H. Bennett, Phys. Rev. Lett. 68, 3121 (1992)] and the four-state BB84 [BB84 refers to the work of C. H. Bennett and G. Brassard, in Proceedings of the IEEE International Conference on Computers, Systems, and Signal Processing, Bangalore, India (IEEE, New York, 1984), pp. 175--179] quantum cryptographic protocols. In each case, the optimal eavesdropping method that on average yields the most information for a given error rate is explicitly constructed. Analysis is limited to eavesdropping strategies where each bit of the quantum transmission is attacked individually and independently from other bits. Subject to this restriction, however, we believe that all attacks not forbidden by physical laws are covered. Unlike previous work, the eavesdropper's advantage is measured in terms of Renyi (rather than Shannon) information, and with respect only to bits received error-free by Bob (rather than all bits). This alters both the maximum extractable information and the optimal eavesdropping attack. The result can be used directly at the privacy amplification stage of the protocol to accomplish secure communication over a noisy channel.
It is generally accepted that quantum key distribution (QKD) could supply legitimate users with unconditional security during their communication. Quite a lot of satisfactory efforts have been achieved on experimentations with quantum cryptography. However, when the eavesdropper has extra-powerful computational ability, has access to a quantum computer, for example, and can carry into execution any eavesdropping measurement that is allowed by the laws of physics, the security against such attacks has not been widely studied and rigorously proved for most QKD protocols. Quite recently, Shor and Preskill proved concisely the unconditional security of the Bennett-Brassard 1984 (BB84) protocol. Their method is highly valued for its clarity of concept and concision of form. In order to take advantage of the Shor-Preskill technique in their proof of the unconditional security of the BB84 QKD protocol, we introduced in this paper a transformation that can translate the Bennett 1992 (B92) protocol into the BB84 protocol. By proving that the transformation leaks no more information to the eavesdropper, we proved the unconditional security of the B92 protocol. We also settled the problem proposed by Lo about how to prove the unconditional security of the B92 protocol with the Shor-Preskill method.
Quantum Cryptography (QKD) uses the laws of Quantum Mechanics to create new cryptographic primitives.Precisely, this technique is based on two laws of quantum mechanics, namely uncertainty principle and no-cloning theorem.The best known QKD is the BB84 protocol published by Bennett and Brassard in 1984.Since then, various QKD protocols have been developed for example a B92 protocol.This latter is similar to that of BB84but this time using only two non-orthogonal states of the four states of BB84.In this work, we develop the java simulation B92 protocol and we give some details of the implementation.Next, we show by an example how Alice (Initiator) can configure the protocol parameters before execution.Finally, we give the statistical results allowing to compare this protocol with that of BB84.
When a quantum cryptographic system operates in the presence of background noise, security of the key can be recovered by a procedure called key distillation. A key-distillation scheme effective against so-called individual (bitwise-independent) eavesdropping attacks involves sacrifice of some of the data through privacy amplification. We derive the amount of data sacrifice sufficient to defend against individual eavesdropping attacks in both BB84 and B92 protocols and show in what sense the communication becomes secure as a result. We also compare the secrecy capacity of various quantum cryptosystems, taking into account data sacrifice during key distillation, and conclude that the BB84 protocol may offer better performance characteristics than the B92.
Secure communication has always been a key concern while sharing information between two parties. Traditional and lightweight cryptography primitives and protocols are insecure against quantum attacks. The objective of cryptography is to ensure confidentiality, integrity, authentication and non-repudiation between both parties. Quantum key distribution is a safe and sound method for communication between two parties to share their information. However early applications with applied limitations lead to open ambiguities, permitting an eavesdropper to breach the security of quantum cryptographic system. This research proposes a framework for quantum key distribution using B92 protocol. The B92 protocol allows two different users A to share their polarized photons with high security and without any interruption of Eavesdropper. While B92 protocol generates a secrete key, that is known to just sender and receiver. The use of QuVis framework can provide this secure communication and photons are transferred to Bob securely without any Eavesdropper.