Authenticated encryption mode with blocks skipping

A V Sokolov,D A Isakov

doi:10.21122/2309-4923-2021-3-59-65

Abstract

Block symmetric ciphers are one of the most important components of modern information security systems. At the same time, in addition to the structure of the applied block symmetric cipher, the cryptographic strength and performance of the information protection system is largely determined by the applied encryption mode. In addition to high performance and high-quality destruction of block statistics, modern encryption modes should also protect encrypted information from occurred or intentionally introduced errors. In this paper, we have developed an encryption mode with blocks skipping and using a pseudo-random key sequence generator, which allows checking the integrity of encrypted information with accurate detection of the place where an error was introduced. In this case, the error detection accuracy is determined by the adjustable parameter of the macroblock size and can be set depending on the level of importance of the protected information. The developed encryption mode is characterized by the following key advantages: reducing the number of required encryption operations by half, while providing a high level of cryptographic quality; more effective destruction of macroblock statistics due to the use of an additional generator of pseudo-random key sequences, the impossibility of propagation of the occurred (intentionally introduced) error outside the macroblock, as well as higher values of the number of protection levels due to the possibility of classifying the initial states of the applied generators of pseudo-random key sequences. As proposed in this paper, the mode of authenticated encryption with blocks skipping can be recommended for use on mobile platforms that are demanding both in terms of the quality and reliability of the protected information and are limited in terms of computing and power resources.

Highlights

Introduction and statement of the problemOne of the most important places in modern complex information protection systems is occupied by the cryptographic subsystem, which ensures the impossibility of obtaining the confidential information without knowing the secret key
Encryption mode is a method of using of a block symmetric cipher that allows you to convert a sequence of blocks of open data into a sequence of blocks of an encrypted data [4]
The simplest known encryption mode is the Electronic Codebook (ECB) mode, which replaces plaintext blocks with ciphertext blocks. It is known [4] that the use of even the most robust block symmetric ciphers in the ECB encryption mode leads to the preservation of block statistics in the original message, which leads to the possibility of partial recovery of encrypted information from the cryptogram

Summary

Introduction and statement of the problem

One of the most important places in modern complex information protection systems is occupied by the cryptographic subsystem, which ensures the impossibility of obtaining the confidential information without knowing the secret key. The simplest known encryption mode is the Electronic Codebook (ECB) mode, which replaces plaintext blocks with ciphertext blocks It is known [4] that the use of even the most robust block symmetric ciphers in the ECB encryption mode leads to the preservation of block statistics in the original message, which leads to the possibility of partial recovery of encrypted information from the cryptogram. This circumstance makes it impossible to apply the ECB mode in practice. The purpose of this paper is to develop an encryption mode with blocks skipping and the use of the PRKSG, which allows checking the integrity of encrypted information with accurate detection of the place where the error was introduced

Encryption Mode with blocks skipping and using of PRKSG

Authenticated encryption mode with block skipping and use of the PRKSG

Findings

Conclusion