We analyze the security for network code when the eavesdropper can contaminate the information on the attacked edges (active attack) and can choose the attacked edges adaptively (adaptive attack). We show that active and adaptive attacks cannot improve the performance of the eavesdropper when the code is linear. Further, we give an non-linear example, in which an adaptive attack improves the pe...

An attack on equipment with laser damage of optical components called " attack", can allow the eavesdropper to reduce attenuation elements and compromise distributed keys. A method protection against this based a device collapsing mirror has been considered. The conclusion experimental data about effectiveness proposed made.. Keywords: quantum key distribution, attack, eavesdr...

Security of an ideal system for quantum key distribution can be formally proved. However, technological imperfections of real systems can be misused by an eavesdropper to get information about the key without causing a detectable change in the error rate. An example of this is the blinding attack where the eavesdropper manipulates detectors of the receiving party. To avoid such an attack, techn...

We present strong attacks against quantum key distribution schemes which use quantum memories and quantum gates to attack directly the final key. We analyze a specific attack of this type, for which we find the density matrices available to the eavesdropper and the optimal information which can be extracted from them. We prove security against this attack and discuss security against any attack...

An algorithm is presented which implements a probabilistic attack on the key-exchange protocol based on Permutation Parity Machines. The strategy consists of a Monte Carlo method to sample the space of possible weights during inner rounds and an analytic approach to convey the extracted information from one outer round to the next one. The results show that the protocol under attack fails to sy...

An algorithm is presented which implements a probabilistic attack on the key-exchange protocol based on permutation parity machines. Instead of imitating the synchronization of the communicating partners, the strategy consists of a Monte Carlo method to sample the space of possible weights during inner rounds and an analytic approach to convey the extracted information from one outer round to t...

The ASM formalism is tailored to develop a general, realistic environment | a computer network possibly monitored by an active eavesdropper | on which any crypto-protocols can be faithfully analysed. The well known Needham-Schroeder protocol with public keys is considered as a case study, and is proven to establish secure sessions between honest agents. The eavesdropper model can reproduce Lowe...

An undetected eavesdropping attack must produce count rate statistics that are indistinguishable from those that would arise in the absence of such an attack. In principle this constraint should force a reduction in the amount of information available to the eavesdropper. In this paper we illustrate, by considering a particular class of eavesdropping attacks, how the general analysis of this pr...

A general study of arbitrary finite-size coherent attacks against continuous-variable quantum cryptographic schemes is presented. It is shown that, if the size of the blocks that can be coherently attacked by an eavesdropper is fixed and much smaller than the key size, then the optimal attack for a given signal-to-noise ratio in the transmission line is an individual gaussian attack. Consequent...

We consider quantum key distribution implementations in which the receiver’s apparatus is fixed and does not depend on his choice of basis at each qubit transmission. We show that, although theoretical quantum key distribution is proven secure, such implementations are totally insecure against a strong eavesdropper that has one-time (single) access to the receiver’s equipment. The attack we pre...