We propose a new key sharing protocol executed through any constant parameter noiseless public channel (as Internet itself) without any cryptographic assumptions and protocol restrictions on SNR in the eavesdropper channels.This protocol is based on extraction by legitimate users of eigenvalues from randomly generated matrices.A similar protocol was proposed recently by G. Qin and Z. Ding.But we prove that, in fact, this protocol is insecure and we modify it to be both reliable and secure using artificial noise and privacy amplification procedure.Results of simulation prove these statements.

The method of secret key sharing between units that did not possess any secret keys in advance is considered.It is assumed that between these units there are duplex wireless MIMO fading channels.In a recent paper published by D. Qin and Z. Dingh a new key sharing protocol has been proposed between legitimate users based on eigenvalues which are invariant under permutation of two matrices in their product.We extend this statement to a characteristic polynomial and by the way to matrix trace.Methods of key bits extraction are optimized both theoretically and experimentally.On the contrary to a statement of D. Qin and Z. Ding we prove that their key sharing protocol occurs insecure if eavesdroppers have the same channels as legitimate users.In order to provide reliability and security of the shared keys both error correction codes and privacy amplification methods can be used.

The method of key sharing between a mobile unit and a base station through a wireless MIMO-based fading channel is investigated.The description of a key distribution protocol is given.The expression to estimate the correct key bit agreement based on the use of guard interval is proved.Statistical properties of the key string are tested using the NIST criteria.Impossibility of key string eavesdropping by illegal users is guaranteed due to small values of correlation between legal and eavesdropper carrier phases.Numerical examples show that the MIMO system with 8 antennas is able to agree 256 bits with a reliability value 0.99 for SNR equal to 35 dB.This experiment confirms that the MIMO scenario is especially effective for secret key distribution.

In this paper, we consider the information-theoretic secure key distribution problem over noisy wiretap channels with public discussion and in the presence of an active adversary. There are several well-known versions of the protocols proposed by Maurer and Wolf to solve this problem. We describe several new versions of the key distribution protocols for the same channel model allowing to increase the key rate given a fixed key security and under an optimization of the protocol parameters. Both asymptotic and nonasymptotic cases are presented. It is shown that in some cases the nonasymptotic key rate is not so far from the asymptotic one whenever the lengths of the transmitted strings are of the order of thousands of bits.

We propose to use the wire-tap channel type 1 concept for protection of information transmitted on digital indoor radio telephone against eavesdropping outside of some secure areas, for example, outside of buildings. The wire-tap channel concept has been proposed by A Wyner (1975) and developed as constructive method by Korjik and Yakovlev (1981, 1992). Use of this approach reduces significantly the sizes of the territory to be secure against possible eavesdropping. A typical degradation is 4-5 times in comparison with the absence of the wire-tap channel concept. In this case the users of indoor radio telephones do not need in encryption/decryption of messages. It is an advantage of this method because there is no problem of key management. The wire-tap channel concept can be used for digital communication only and it requires an increase in the rate of signaling over the channel. Typical examples of the indoor radio links protected by the "wire-tap channel concept" are given.