Лесна криптографија од перспектива на теоријата на квазигрупи

Abstract

In this Ph.D. thesis is given a completely new design and implementation of an algorithm for authenticated encryption, -Cipher. -Cipher is one of the ciphers that participate in the second round vaof Competition for Authenticated Encryption: Security, Applicability, and Robustness - CAESAR. -Cipher is parallel, incremental, with intermediate tags, nonce-based authenticated encryption cipher with associated data. It is designed with a special purpose to offer prin vacy and integrity of data that use constrained resources, as well as the big data at rest or in transit. It has a special option for using the secret part of the nonce (SMN), that gives the cipher an extra robustness feature and an intermediate level of nonce-misuse resistance. Instead of the standard schemes that use block ciphers, -Cipher as a cryptographic primitive is a permutation-based scheme. Its permutation function is based on the operations: addition, rotation, and xor. Also, its design involves several solid cryptographic concepts such as a composition scheme for authenticated encryption, Encrypt-than-MAC, a counter based XOR-MAC scheme, and the duplex sponge construction. -Cipher is designed for different word sizes and different security levels from 96 to 256 bits. For lightweight implementations, we propose the variant 16-Cipher096 where the word size is 16-bit and security level 96-bit. For standard and high-performance implementations, we propose the variants with 32-bit and 64-bit word sizes.