A method for operative sharing confidential images among a group of trusted users

Abstract

Encryption of high-resolution images plays a key role in ensuring their confidentiality and integrity. Given the rapid growth of traffic of such images in open communication channels, the development of new methods and means of their protection is becoming increasingly actual. The objective of this study is to develop and model a method for exchanging confidential images for a group of trusted users. In the process of the study, encryption methods with chaotic maps, cryptography on elliptic curves, and agreement group secret agreement with various protocols were used . One of the requirements for the method being developed is its operation on a time scale close to real. This is due to the rapid aging of information in images subject to analysis in the group. The study is based on the method of generating a pseudo-random sequence using a modified chaotic map Tent. A short key containing the parameters of this map is transmitted to trusted users who form the group. Then each user can expand the key into a pseudo-random sequence and encrypt/decrypt the image with the Vernam cipher . A group of trusted users is formed using the Diffie-Hellman protocol or Burmester-Desmedt on elliptic curves. The Weierstrass, Montgomery and Edwards curves were analyzed from the point of view of computational costs. The Montgomery curve was chosen as the most computationally efficient working elliptic curve. To transfer to a group of trusted users, the short key of Tent map is encrypted with a block cipher with a secret as the key. The developed method is modeled for the curve Montgomery Curve25519. Image security and confidentiality are ensured by five levels of protection. As a result, it was found that group formation according to the Burmester-Desmedt protocol ensures the operation of the method on a time scale close to real time and a high level of scalability.