Providing Stability and Correctness of Cryptosystem Functioning under Condition of Authenticity Loss of Part of Key Material

A notion of authenticity is introduced as one of security aspects of the cryptosystem key material. Theoretical statements are set forth which specify a system of factors and criteria to provide the authenticity of keys. The proved declarations and theorems on the structure of the key system providing the satisfaction of the authenticity requirements are given. Examples of analysis of authenticity factors for some typical elements of the key systems are presented.