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.
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 this work, we propose a generalization of the concept of chameleon hash first described in [Krawczyk and Rabin 1998], which we call preimage chameleon hash. While in the conventional chameleon hash, the trapdoor allows a user to compute second preimages, in this generalization, it is possible to compute first preimages. We show how to adapt the post-quantum chameleon hash from [Cash et al. 2010] to a preimage chameleon hash and use this modified construction to build a new signature scheme based on [Mohassel 2011]. A preimage chameleon hash allows the signer to encode in its signature chosen information to be checked during verification. We prove our signature scheme to be strongly unforgeable under a chosen message attack (SUF-CMA).
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.
Hash functions play a fundamental role in cryptography, offering one-way and collision-resistant properties essential for digital security. Chameleon hashing, an extension of traditional hash functions, allows controlled collision generation using a private trapdoor, enabling various cryptographic applications such as online/offline digital signatures and commitment schemes. However, existing identity-based chameleon hash (IBCH) functions largely rely on number-theoretic assumptions, which are vulnerable to quantum attacks. To address this issue, we propose a novel IBCH function built upon post-quantum lattice-based cryptography. Specifically, our construction leverages the Short Integer Solution (SIS) problem to achieve quantum-resistant security guarantees. The proposed scheme enables identitybased key management, allowing users to generate hash values using public identity information while preserving the trapdoorcontrolled collision property. We rigorously analyze the security of our scheme, demonstrating its resistance against quantum adversaries under standard lattice assumptions. Furthermore, we compare our construction with existing functions in terms of computational efficiency and security, showing that our approach provides a feasible and secure alternative for post-quantum applications.
Signature schemes, proposed in 1976 by Diffie and Hellman, have become ubiquitous across modern communications. They allow for the exchange of messages from one sender to multiple recipients, with the guarantees that messages cannot be forged or tampered with and that messages also can be forwarded from one recipient to another without compromising their validity. Signatures are different from, but no less important than encryption, which ensures the privacy of a message. Commonly used signature protocols—signatures based on the Rivest–Adleman–Shamir (RSA) algorithm, the digital signature algorithm (DSA), and the elliptic curve digital signature algorithm (ECDSA)—are only computationally secure, similar to public key encryption methods. In fact, since these rely on the difficulty of finding discrete logarithms or factoring large primes, it is known that they will become completely insecure with the emergence of quantum computers. We may therefore see a shift towards signature protocols that will remain secure even in a post-quantum world. Ideally, such schemes would provide unconditional or information-theoretic security. In this paper, we aim to provide an accessible and comprehensive review of existing unconditionally securesecure signature schemes for signing classical messages, with a focus on unconditionally secure quantum signature schemes.
Traditional digital signatures are often publicly verifiable, and in certain applications with privacy preservation requirements, the signer does not want the sensitive information it signed to be redelivered by a dishonest verifier.Aiming at the problem that traditional chameleon signatures (CS) cannot resist quantum computer attacks, this paper proposes a lattice-based authentication CS scheme.Based on the analysis of the lattice difficulty problem and the security vulnerability of the CS scheme, it is pointed out that it does not satisfy the third-party unforgeability and the signer rejectability, and a new lattice-based identity CS scheme is established, which is verified under the stochastic predicate machine model, and the storage and transmission efficiency of the scheme is analyzed.The results show that the newly designed identity-based CS scheme on the lattice can effectively resist quantum computer attacks, can sign messages of arbitrary length, and possesses more lightweight storage and transmission efficiency.The optimized chameleon signature scheme has better security and also provides a new solution for digital signatures to resist quantum computer attacks.
The use of public key cryptosystems range from securely encrypting emails and files to creating digital signatures for non-repudiation. The security of public key cryptosystems is based on computationally "unsolvable" complex mathematical problems. This tends to change with the introduction of quantum computers that undoubtedly pose a threat to the current schemes. In response to that extensive research has been conducted that resulted in several cryptosystems that are believed to be quantum resistant. This thesis presents a concise overview of multiple hash-based signature schemes and provides a comparative description and analysis of them. The comparisons are based on different signature scheme properties, such as key sizes, signature sizes and security level provided. The proposed quantum resistant schemes are also compared to the standard schemes used today, such as RSA and ECDSA.