On message protection in cryptosystems modelled as the generalized wire-tap channel II

Abstract

A novel approach to the analysis of message security in cryptosystems which can be modelled as the generalized wire-tap channel II is considered. Roughly speaking, the codewords transmitted through this channel are degraded by the deletion of a number of bits and by the complementing of a number of the remaining bits. It is assumed that the channel output codewords are available to a cryptanalyst. The security of the messages is measured by the uncertainty after certain minimum distance decoding (MDD) procedures are applied to the received code­words. A novel distance measure relevant to MDD is proposed, and the remaining uncertainty after MDD is analyzed. An extension of the approach is also considered.