There are presented theoretical bases of entropy calculation for random messages. The analytical expressions of known entropy estimates are classified. A comparative analysis of the information characteristics for the estimates of the probability and correlation measures of entropy is performed. There is also reviewed the scope of entropy analysis, software and hardware tools for entropy calculation. The characteristics of hardware and time complexity of circuit-technical solutions of special entropy calculation processors are developed. There is proposed an extension of Shannon's entropy estimation functionalities and development of special processors for the forming and receiving of crypto-protected entropy-manipulated signals in the environment of cyber-physical systems.