arXiv subjects

Gennady Khalimov

Publications and source records attributed to Gennady Khalimov.

11 recordsLinked to original sources

arXiv2026

LINEture: novel signature cryptosystem

We propose a novel digital signature cryptosystem that exploits the concept of the brute-force problem. To ensure the security of the cryptosystem, we employed several mechanisms: sharing a common secret for factorable permutations, associating permutations with the message being signed, and confirming knowledge of the shared secret using a zero-knowledge proof. We developed a secret-sharing theory based on homomorphic matrix transformations for factorized permutations. The inverse matrix transformation for computing the shared secret is determined by secret parameters, which results in incompletely defined functionality and gives rise to a brute-force cryptanalysis problem. Randomization of session keys using a message hash and random parameters guarantees the uniqueness of each signature, even for identical messages. We employed a zero-knowledge authentication protocol to confirm knowledge of the shared secret, thereby protecting the verifier against unauthorized signature imposition. The LINEture cryptosystem is built on linear matrix algebra and does not rely on a computationally hard problem. High security is achieved through the appropriate selection of matrix transformation dimensions. Matrix computations potentially offer low operational costs for signature generation and verification.

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arXiv2026

Security Parameter Analysis of the LINEture Post-Quantum Digital Signature Scheme

This paper presents a comprehensive cryptographic analysis of the security parameters of the LINEture post-quantum digital signature scheme, which is constructed using matrix algebra over elementary abelian 2-groups. We investigate the influence of three principal parameters. First, the word size m (exhibiting quadratic impact), the second is a vector dimension l, and the third is a number of submatrices in the session key q (exhibiting linear impact) on cryptographic strength. Our analysis reveals a dualistic nature of the parameter l. According to the previous analysis, it does not affect resistance to guessing attacks. A deeper examination of the verification mechanism demonstrates that l establishes a kind of verification barrier of l times m bits. We establish the threshold relationship l less q minus 1 times m, below which parameter l becomes security-critical. The optimal selection rule l near q minus 1 times m is proposed for maximum cryptographic efficiency. Comparative analysis with NIST PQC standards and practical parameter recommendations are provided.

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arXiv2025

LINE: Public-key encryption

We propose a public key encryption cryptosystem based on solutions of linear equation systems with predefinition of input parameters through shared secret computation for factorizable substitutions. The existence of multiple equivalent solutions for an underdetermined system of linear equations determines the impossibility of its resolution by a cryptanalyst in polynomial time. The completion of input parameters of the equation system is implemented through secret homomorphic matrix transformation for substitutions factorized over the basis of a vector space of dimension m over the field F2. Encryption is implemented through computation of substitutions that are one-way functions on an elementary abelian 2-group of order 2"m. Decryption is implemented through completion of input parameters of the equation system. Homomorphic transformations are constructed based on matrix computations. Matrix computations enable the implementation of high security and low computational overhead for homomorphic transformations.

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arXiv2025

Secured Encryption scheme based on the Ree groups

An improved design of a cryptosystem based on small Ree groups is proposed. We have changed the encryption algorithm and propose to use a logarithmic signature for the entire Ree group. This approach improves security against sequential key recovery attacks. Hence, the complexity of the key recovery attack will be defined by a brute-force attack over the entire group. In this paper, we have proved that to construct secure cryptosystems with group computations over a small finite field, it is needed to use a 3-parametric small Ree group.

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arXiv2025

MST3 Encryption improvement with three-parameter group of Hermitian function field

This scholarly work presents an advanced cryptographic framework utilizing automorphism groups as the foundational structure for encryption scheme implementation. The proposed methodology employs a three-parameter group construction, distinguished by its application of logarithmic signatures positioned outside the group's center, a significant departure from conventional approaches. A key innovation in this implementation is utilizing the Hermitian function field as the underlying mathematical framework. This particular function field provides enhanced structural properties that strengthen the cryptographic protocol when integrated with the three-parameter group architecture. The encryption mechanism features phased key de-encapsulation from ciphertext, representing a substantial advantage over alternative implementations. This sequential extraction process introduces additional computational complexity for potential adversaries while maintaining efficient legitimate decryption. A notable characteristic of this cryptosystem is the direct correlation between the underlying group's mathematical strength and both the attack complexity and message size parameters. This relationship enables precise security-efficiency calibration based on specific implementation requirements and threat models. The application of automorphism groups with logarithmic signatures positioned outside the center represents a significant advancement in non-traditional cryptographic designs, particularly relevant in the context of post-quantum cryptographic resilience.

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arXiv2025

$\mathcal{PT}$-symmetric mapping of three states and its implementation on a cloud quantum processor

$\mathcal{PT}$-symmetric systems have garnered significant attention due to their unconventional properties. Despite the growing interest, there remains an ongoing debate about whether these systems outperform their Hermitian counterparts in practical applications, and if so, by what metrics this performance should be measured. We developed $\mathcal{PT}$-symmetric approach for mapping $N = 3$ pure qubit states to address this, implemented it using the dilation method, and demonstrated it on a superconducting quantum processor from the IBM Quantum Experience. For the first time, we derived exact expressions for the population of the post-selected $\mathcal{PT}$-symmetric subspace for both $N = 2$ and $N = 3$ states. When applied to the discrimination of $N = 2$ pure states, our algorithm provides an equivalent result to the conventional unambiguous quantum state discrimination. For $N = 3$ states, our approach introduces novel capabilities not available in traditional Hermitian systems, enabling the transformation of an arbitrary set of three pure quantum states into another, at the cost of introducing an inconclusive outcome. Our algorithm has the same error rate for the attack on the three-state QKD protocol as the conventional minimum error, maximum confidence, and maximum mutual information strategies. For post-selected quantum metrology, our results provide precise conditions where $\mathcal{PT}$-symmetric quantum sensors outperform their Hermitian counterparts in terms of information-cost rate. Combined with punctuated unstructured quantum database search, our method significantly reduces the qubit readout requirements at the cost of adding an ancilla, while maintaining the same average number of oracle calls as the original punctuated Grover's algorithm. Our work opens new pathways for applying $\mathcal{PT}$ symmetry in quantum communications, computing, and cryptography.

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arXiv2025

Advanced MST3 Encryption scheme based on generalized Suzuki 2-groups

This article presents a method for enhancing the encryption algorithm in the MST3 cryptosystem for generalized Suzuki 2-groups. The conventional MST cryptosystem based on Suzuki groups utilizes logarithmic signatures (LS) restricted to the center of the group, resulting in an expansive array of logarithmic signatures. We propose an encryption scheme based on multi-parameter non-commutative groups, specifically selecting multi-parameter generalized Suzuki 2-groups as the group construction framework. In our approach, the logarithmic signature extends across the entire group, with cipher security dependent on the group order. This design enables the development of encryption optimized for implementation efficiency determined by logarithmic signature size while maintaining robust security through appropriate key sizes and the finite field of group representation. The primary innovation in our encryption implementation lies in the sequential de-encapsulation of keys from ciphertext using logarithmic signatures and associated keys. The security evaluation of the cipher relies on attack complexity analysis, which is quantified through comprehensive key enumeration methodologies.

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arXiv2025

Improved MST3 Encryption scheme based on small Ree groups

This article presents an encryption scheme based on the small Ree groups. We propose utilizing the small Ree group structure to enhance the overall security parameters of the encryption scheme. By extending the logarithmic signature to encompass the entire group and modifying the encryption algorithm, we have developed robust protection against sequential key recovery attacks.

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arXiv2025

Cryptographic Strengthening of MST3 cryptosystem via Automorphism Group of Suzuki Function Fields

The article describes a new implementation of MST3 cryptosystems based on the automorphism group of the Suzuki function field. The main difference in the presented implementation is to use the logarithmic signature for encryption not only in the center of the group, as in the well-known implementation of MST3 for Suzuki groups but also for coordinates outside the center of the group. The present implementation of a cryptosystem has higher reliability. The complexity of cryptanalysis and the size of the message for encryption squared is higher than that of the MST3 cryptosystem in the Suzuki group.

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arXiv2025

Encryption scheme based on Automorphism Group of Hermitian Function Field with Homomorphic Encryption

This article proposes a comprehensive approach to implementing encryption schemes based on the automorphism group of the Hermitian function field. We utilize a three-parameter group with logarithmic representations outside the group's center. In this work, we enhance the Hermitian function field-based encryption scheme with homomorphic encryption capabilities, which constitutes a significant advantage of our implementation. Both the attack complexity and the encrypted message size are directly correlated with the order of the group.

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arXiv2024

SIGNLINE: Digital signature scheme based on linear equations cryptosystem

The paper explores a novel cryptosystem for digital signatures based on linear equa-tions for logarithmic signatures. A logarithmic signature serves as a fundamental cryptographic primitive, characterized by properties such as nonlinearity, non-commutability, unidirectionality, and key-dependent factorability. The proposed cryptosystem ensures the secrecy of logarithmic signatures through its foundation in linear equations. Quantum security is achieved by eliminating any possible mapping between the input and output of the logarithmic signature, thereby rendering Grover's quantum attack ineffective. The public key sizes for the NIST security levels of 128, 192, and 256 bits are 1, 1.5, and 2 KB, respectively. The algorithm demonstrates scalability concerning computational costs, memory usage, and hardware limitations without compromising security. Its primary operation involves bitwise XOR over logarithmic arrays of 8, 16, 32, and 64 bits.

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