Abstract. We show how to extend hash-tree based data signatures to server-assisted personal digital signature schemes. The new signature scheme does not use trapdoor functions and is based solely on cryptographic hash functions and is thereby, considering the current state of knowledge, resistant to quantum computational attacks. In the new scheme, we combine hash-tree data signature (timestamping) solutions with hash sequence authentication mechanisms. We show how to implement such a scheme in practice. 1
Abstract. We show how to extend hash-tree based data signatures to server-assisted personal digital signature schemes. The new signature scheme does not use trapdoor functions and is based solely on cryptographic hash functions and is thereby, considering the current state of knowledge, resistant to quantum computational attacks. In the new scheme, we combine hash-tree data signature (timestamping) solutions with hash sequence authentication mechanisms. We show how to implement such a scheme in practice. 1
Quantum computing presents a significant threat to traditional cryptographic protocols, particularly those relying on the hardness of factoring large integers and computing discrete logarithms, as quantum algorithms can solve these problems in polynomial time. With the advent of quantum computers capable of breaking current cryptographic schemes, the need for quantum-resistant cryptographic mechanisms has become increasingly urgent. In this paper, we focused on authentication, a critical security property, and reviewed various classical cryptographic techniques to this aim and their potential to resist quantum attacks. We present a (non-exhaustive) overview of the state of the art in quantum-resistant authentication, particularly through symmetric cryptography, digital signatures, and hardware-based approaches such as physical unclonable functions (PUFs). By offering a clear and focused analysis, we used this survey to bridge the gap between diverse academic communities and provide a foundation for future research in post-quantum authentication.
As a standard digital signature may be verified by anybody, it is unsuitable for personal or economically sensitive applications. The chameleon signature system was presented by Krawczyk and Rabin as a solution to this problem. It is based on a hash then sign model. The chameleon hash function enables the trapdoor information holder to compute a message digest collision. The holder of a chameleon signature is the recipient of a chameleon signature. He could compute collision on the hash value using the trapdoor information. This keeps the recipient from disclosing his conviction to a third party and ensures the privacy of the signature. The majority of the extant chameleon signature methods are built on the computationally infeasible number theory problems, like integer factorization and discrete log. Unfortunately, the construction of quantum computers would be rendered insecure to those schemes. This creates a solid requirement for construct chameleon signatures for the quantum world. Hence, this paper proposes a novel quantum secure chameleon signature scheme based on hash functions. As a hash-based cryptosystem is an essential candidate of a post-quantum cryptosystem, the proposed hash-based chameleon signature scheme would be a promising alternative to the number of theoretic-based methods. Furthermore, the proposed method is key exposure-free and satisfies the security requirements such as semantic security, non-transferability, and unforgeability.
In the era of active information technologies and device development, the emergence of portable and general-purpose quantum computers is only a matter of time. And although the benefit of their many times greater efficiency, compared to ordinary bit computers, will be obvious, at the same time, they will bring many vulnerabilities to modern algorithms of cryptography and cybersecurity. To prevent this from happening, society has already started researching post-quantum protocols to replace modern ones. Digital signature protocols were no exception. Thus, one of the approaches was constructing post-quantum digital signature protocols based on hash functions. The first representatives were schemes of one-time signatures based on hash functions, which were protected from the capabilities of quantum computers but had the obvious disadvantage of one-time use. The most famous is the so-called Lamport one-time signature. However, this disadvantage of one-time use has been solved by proposing different schemes of multi-time digital signatures based on the creation and use of many one-time signatures. Thus, chain-based and tree-based schemes of multi-time signatures were proposed. This work is devoted to the implementation and comparison of various multi-time signature schemes. During the research, theoretical estimates of memory usage and time required for the operations of various schemes were given. Further implementation of these schemes and final measurements showed the correspondence of theoretical estimates with empirical results and clearly demonstrated the advantages and disadvantages of different schemes. Thus, tree-based schemes showed the best performance, especially those where the tree is built sequentially. However, in certain cases, it makes sense to use a tree with full-depth construction. Due to the relative novelty and small amount of research in this field, multi-time digital signatures have much room for further research, for example, considering N-ary trees and comparing them with binary ones.
Digital signatures are unsuitable for specific applications that are sensitive on a personal or commercial level because they are universally verifiable. Jakobsson et al. proposed the Designated Verifier Signature (DVS) system, which only allows the intended verifier to validate a message’s signature. It prohibits the disclosure of a conviction to a third party. This functionality is useful in applications that require both authenticity and signer privacy, such as electronic voting and tender calls. The vast majority of current DVS schemes are based on difficult number theory problems such as integer factorization or discrete log problems over various groups. The development of a large-scale quantum computer would render these schemes unsafe. As a result, it is critical to develop quantum-resistant DVS methods. In both quantum and classical computers, signatures based on one-way functions are more efficient and secure. They have several advantages over digital signatures based on trapdoor functions. As a result, hash-based signatures are now considered viable alternatives to number-theoretic signatures. Existing hash-based signatures, on the other hand, are easily verifiable by anyone. As a result, they do not protect the signer’s identity. In addition, they are one-time signatures. This paper presents a hash-based multi-time designated verifier signature scheme that ensures signer anonymity. The unforgeability of the signature scheme is also tested in the random oracle model under chosen message attack. The properties such as non-transferability and non-delegatability are investigated.
The rapid development of quantum computing poses challenges to the foundations of traditional cryptography. The threats are significant in terms of both asymmetric cryptography (which exposes schemes like RSA and ECC to efficient attacks) and symmetric cryptography, where key sizes must be increased to mitigate these threats. In this paper, we review the evolution of hash-based digital signatures, from early one-time signatures to modern stateless schemes, with an emphasis on their security properties, efficiency, and practical constraints. Moreover, we propose a simple comparative metric that reflects structural symmetry across key parameters such as key size, signature size, and computational cost, enabling a visual clustering of the schemes. We give particular attention to recent developments such as Verkle trees, which preserve symmetric design principles while improving scalability and proof compactness. The study highlights ongoing tradeoffs between stateful and stateless designs and argues for the continued relevance of symmetric cryptographic constructions in building secure, efficient post-quantum systems.
Communication and networked systems rely heavily on cryptographic digital signatures to ensure message authenticity, integrity, and non-repudiation. However, rapid advancements in quantum computing and artificial intelligence (AI) have expanded the attack surface, posing significant threats to conventional public-key schemes such as RSA, DSA, and ECDSA. Quantum algorithms undermine their underlying hardness assumptions, while AI-driven techniques enable traffic analysis, side-channel inference, and behavioral pattern recognition. This review presents a structured analytical assessment of post-quantum signature schemes and privacy-preserving authentication mechanisms to address these dual threats. It evaluates lattice-based, hash-based, and zero-knowledge proof-based signatures, as well as anonymity-enhancing schemes such as ring and group signatures. A unified analytical framework is introduced to map cryptographic schemes to quantum and AI-assisted threat models, based on parameters such as security strength, anonymity, efficiency, and applicability. The analysis shows that lattice- and hash-based schemes provide strong quantum resistance, while privacy-preserving mechanisms enhance anonymity but introduce performance trade-offs. It also identifies a gap in integrating post-quantum cryptography with AI-resilient privacy mechanisms. The findings highlight the need for unified, future-ready cryptographic designs.