Asymmetric Secret Key Transfer Scheme over an Open Channel in K-Deterministic Groups with the Conditions C (3) –T (6)

Abstract

The article solves a problem of developing a scheme to provide a secret key exchange over an open communication channel. The basic idea of creating such a scheme is well known. It is based on a concept of the one-way function. This refers to the functions whose values are calculated much easier than the inverse function values. When developing the one-way functions a recognition algorithm of words equality in groups with conditions of small cancellation C (3) - T (6) is used. In this case, the group is represented by a set of its generating and determining relations. All the work to accomplish development of algorithms and evaluate their complexity is carried out using the group diagrams of equality. The existence of such diagrams is proved in the well-known van Campen lemma. The paper result is that the proposed scheme for the exchange of secret keys has the following properties. Direct algorithms have a linear complexity, and a complexity of the inverse algorithms is exponential. It should be noted that the algorithms complexity was estimated by the areas of the corresponding group diagrams, which are determined by the number of areas they include. The constructed secret key represents some element of a pre-selected group with conditions C (3) – T (6). It can be represented in an infinite number of ways by words in the alphabet from the generators of the group. Thus, the remaining obstacle to the practical application of the key exchange scheme developed is the ambiguity of the secret key record. Finding a common representative as the lexicographically shortest word in the class of equal words turns out to be too difficult. Thus, this question remains open. Although the task of exchanging secret keys itself can be formally considered as solved.