The distinguishing feature of hash-based algorithms is their high confidence in security. When designing electronic signature schemes, proofs of security reduction to certain properties of cryptographic hash functions are used. This means that if the scheme is compromised, then one of these properties will be violated. It is important to note that the properties of cryptographic hash functions have been studied for many years, but if a specific hash function used in a protocol turns out to be insecure, it can simply be replaced with another one while keeping the overall construction unchanged. This article describes a new post-quantum signature algorithm, Syrga-1, based on a hash function. This algorithm is designed to sign r messages with a single secret key. One of the key primitives of the signature algorithm is a cryptographic hash function. The proposed algorithm uses the HAS01 hashing algorithm developed by researchers from the Information Security Laboratory of the Institute of Information and Computational Technologies. The security and efficiency of the specified hash algorithm have been demonstrated in other articles by its authors. Hash-based signature schemes are attractive as post-quantum signature schemes because their security can be quantified, and their security has been proven.

A new symmetric block cipher algorithm called AL02 has been developed. The algorithm scheme provides five-round encryption of 128-bit blocks, while the data size at the input and output of the S-box is 8 bits. The main transformation is the F transformation. The difference between the proposed algorithm and the classical scheme is that the F transformation provides the maximum possible dependence of the output vector bits on the input bits and is based on “modulo 2 addition” and a substitution S-box. To assess the strength of the AL02 algorithm, it was programmatically implemented in the C programming language. During the analysis, the cryptographic properties of the developed encryption algorithm were tested. The algorithm was tested for statistical security. For an experimental assessment, in order to ensure that the ciphertext is not inferior to a random sequence in its properties, the well-known sets of statistical tests by NIST (National Institute of Standards and Technology) and Donald Knuth were used. The property of the avalanche effect was also checked. The strength was evaluated using the methods of differential and linear cryptanalysis.

The article observes the new hashing algorithm HBC-256. The HBC-256 algorithm is based on the block cipher of the compression function CF (Compression Function) and produces a 256-bits hash value. Like any new cryptographic structure, the HBC-256 algorithm requires careful research process in order to confirm its cryptographic properties, namely: pre-image resistance and resistance to collisions of the first and second order. As a result of the research, for the HBC-256 hashing algorithm differential properties of nonlinear elements (S-boxes) and various options for constructing round characteristics are considered. A hypothesis has been advanced about the existence of paired differences, which will make it possible to construct round characteristics for hashing and for the function of round keys generating. It is shown that even for the most optimal way of constructing chains of differences, the probability of finding correct pairs of texts is less than the probability of a complete enumeration of one 128-bit block of input data, which makes the method of differential cryptanalysis unsuitable for finding collisions.

This paper proposes an approach based on a secret sharing scheme with the mandatory participation of predefined subgroups. The proposed scheme allows secret reconstruction only when representatives from each designated group of participants (e.g., cloud providers, legally independent parties, etc.) are present. This mechanism enhances resistance to internal collusion, strengthens access control, and enables distributed management. The structure and mathematical foundations of the proposed scheme are presented, along with an analysis of its properties. A cryptanalysis is conducted, evaluating the scheme’s resilience to various types of attacks, and the results are discussed. The computational complexity of the algorithm is also analyzed, and its resource efficiency is confirmed.