Chameleon Signatures Research Articles

Tightly-Secure Two-Tier Signatures on Code-Based Digital Signatures with Chameleon Hash Functions

In the current landscape where quantum algorithms pose a significant threat to conventional digital signature algorithms, code-based digital signature algorithms have emerged as the primary focus of ongoing research in post-quantum cryptography. Digital signatures play a pivotal role in ensuring non-repudiation and authentication, making them an indispensable cryptographic technique. The vulnerability of most digital signature algorithms to quantum attacks have prompted a significant surge in research on code-based digital signature algorithms, which have emerged as a prominent field within post-quantum cryptography. There are generally three distinct approaches to constructing code-based digital signature algorithms: (1) Developing an algorithm that follows the inverse process of the code-based public-key encryption algorithm; (2) Utilizing zero-knowledge identification algorithms in conjunction with the Fiat–Shamir paradigm to formulate a signature algorithm; (3) Constructing a specialized subset of the syndrome space as the foundation for the digital signature algorithm. Chameleon Signature is a non-interactive signature that operates on the hash and signature paradigm, exhibiting comparable efficiency to conventional schemes. Its distinct advantage lies in the fact that the owner of the public key does not necessarily require access to the corresponding secret key within the Chameleon hash algorithm. Notably, Chameleon signatures possess an inherent characteristic of non-transferability, with their validity ascertainable solely by designated recipients. This paper introduces the first Chameleon hash function based on both KKS and HFE schemes, showcasing its superiority over traditional schemes through rank metrics and big fields for enhanced security. The deployment of Chameleon hash functions within hash-and-sign signature schemes introduces a nuanced layer of security and verification flexibility. This study elucidates the implications of integrating Chameleon hash functions into the recipient’s public key infrastructure, highlighting the dual capability it affords authorized parties for secure and adaptable verification processes, alongside mechanisms for the detection of unauthorized alterations.

Privacy-Preserving Medical Data-Sharing System with Symmetric Encryption Based on Blockchain

Nowadays, data between hospitals are usually not interoperable, which brings great inconvenience to medical data sharing and patients’ medical treatment. In addition, patients do not want their medical data to be leaked during the sharing process. Researchers have employed blockchain to build data-sharing systems to address these issues. However, current systems do not restrict the power of participants, nor do they prevent visitors from sharing the obtained data to unauthorized parties. To address these issues, we propose a private data-sharing system with symmetric encryption for the medical industry that implements power restriction and access control, and prevents the leakage of private data. To be specific, firstly, symmetric encryption algorithm is utilized to encrypt medical data to protect the privacy of data owner. Secondly, our proposed system is built on a new blockchain framework, in which only visitors with permission can access the medical data. Thirdly, we employ chameleon signature to prevent visitors from sharing data with other parties without permission. Finally, we make the power of participants in the system revocable to prevent them from abusing their power. Our proposed system has been proven to be secure through security analysis and can protect the privacy of patients. In addition, the experimental results show that our system has excellent performance in terms of time overhead compared to other systems.

A Secure Authentication Framework to Guarantee the Traceability of Avatars in Metaverse

Metaverse is a vast virtual environment parallel to the physical world in which users enjoy a variety of services acting as an avatar. To build a secure living habitat, it’s vital to ensure the virtual-physical traceability that tracking a malicious player in the physical world via his avatars in virtual space. In this paper, we propose a two-factor authentication framework based on biometric-based authentication and chameleon signature. First, aiming at disguise in virtual space, we design an avatar’s two-factor identity model to ensure the verifiability of avatar’s virtual identity and physical identity. Second, facing at authentication efficiency and keys holding cost, we propose a chameleon collision signature algorithm to efficiently ensure that the avatar’s virtual identity is associated with its physical identity. Finally, aiming at impersonation in the physical world, we design two decentralized authentication protocols based on the avatar’s identity model and the chameleon collision signature to achieve real-time authentication on the avatar’s identity. Security analysis indicates that the proposed authentication framework guarantees the consistency and traceability of the avatar’s identity. Simulation experiments show that the framework not only completes the decentralized authentication between avatars but also achieves virtual-physical tracking.

A Multisignature-Based Secure and OBU-Friendly Emergency Reporting Scheme in VANET

Acting as an important part of Internet of Things (IoTs), vehicular ad-hoc network (VANET) has attracted considerable attention in recent years, where the emergency reporting system is a significant branch and can improve road safety and optimize traffic management. In an emergency reporting system, the authenticity of the emergency messages needs to be ensured carefully since malicious entities may report fake emergency messages to seek personal profit. However, most existing emergency reporting schemes are not efficient enough for secure reporting, given the limited resources of onboard units (OBUs). In this work, we propose a new emergency reporting architecture based on multisignature, where the computation and communication overhead of road-side units (RSUs) is greatly reduced, as the signatures sent to the RSUs have been aggregated. Then, we transform a chameleon signature into a multisignature and propose a secure and OBU-friendly emergency reporting scheme (SOERS) under our architecture. The proposed scheme only requires one hash, two multiplication, and two addition operations to generate a signature for each OBU. Moreover, batch verification of multisignatures further improves the efficiency. Security analysis shows that our scheme is secure against the vehicles-collusion attack and the rogue-key attack, which is a severe issue in multisignature. Finally, performance evaluation shows that our scheme is an efficient solution for emergency reporting.

A Hash-Based Quantum-Resistant Chameleon Signature Scheme.

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.

FASE: Fine-Grained Accountable and Space-Efficient Access Control for Multimedia Content With In-Network Caching

To reduce the duplicated traffic and improve the performance of distributing massive volumes of multimedia contents, in-network caching has been proposed recently. However, as in-network content caching can be directly utilized to respond users’ requests, multimedia content retrieval is beyond content providers’ control and makes it hard for them to implement access control and service accounting. In this paper, we propose a Fine-grained Accountable and Space-Efficient access control scheme, called FASE, for multimedia content distribution. FASE allows content providers to be fully offline while making the best of in-network caching. In FASE, the attribute-based encryption at multimedia content provider side and access policy based authentication at the edge router side jointly ensure secure fine-grained access control. Our scheme is efficient in both space and time. By designing one time chameleon signature (OTCS), users can keep anonymous during the authentication, and their privileges can be conveniently revoked when needed. Besides, secure service accounting is implemented by letting edge routers collect service credentials generated during users’ request process. Through formal security analysis, we prove the security of our scheme. Simulation results demonstrate that our scheme is efficient with acceptable overhead.

Security Analysis and Improvement of a Redactable Consortium Blockchain for Industrial Internet-of-Things

Abstract A redactable consortium blockchain (RCB) can build a trust layer for industrial internet of things (IIoT) so as to enable IIoT to resist certain powerful attacks resulting in improper block content. The redactability is particularly important for blockchains applied in IIoT with valuable or sensitive activities such as financial IoT or energy-trading IoT. Huang et al. proposed a threshold chameleon hash (TCH) scheme and then constructed an accountable-and-sanitizable chameleon signature scheme based on TCH. These two primitives are further used as fundamental modules to build an RCB, which empowers IIoT devices to operate the blockchain in a controllable way. However, our paper shows that Huang et al.’s RCB suffers from a security problem that weakens the crucial redactability. Specifically, we find out that if a transaction in a given block is legally redacted by all authorized sensors who collectively hold the private redacting key, anyone (without any private information) can further redact this redacted transaction and delete any transaction within this redacted block and, meanwhile, any sensor user with a private signing (not redacting) key can insert a forged transaction into this redacted block. We further address this threat by replacing the TCH module in Huang et al.’s RCB with our designed TCH.

Quantum resistant key-exposure free chameleon hash and applications in redactable blockchain

Blockchain technologies have attracted a large amount of attention recently, with immutability as a basic property. However, it is often desired to allow editing a transaction or a block in a controlled way. Chameleon hash function, with enhanced collision-resistance property, has recently found to be an important tool to construct redactable blockchain. This means that the traditional key-exposure free (double-trapdoor) constructions are unsuitable for the applications here. Although single-trapdoor key-exposure free chameleon hash functions naturally satisfy enhanced collision-resistance, they are very rare, and none is based on quantum-resistant assumptions.In this paper, we propose two single-trapdoor key-exposure free chameleon hash functions based on lattice, without/with lattice trapdoors respectively, and show their applications in redactable blockchain. Our constructions do not need heavy cryptographic tools, such as encryption and NIZK, therefore are more compact and computational efficient than schemes following Ateniese et al.’s generic transformation framework of PKE+NIZK. Moreover, we introduce two mechanisms in order to prevent the misuse of redaction functionality in blockchain. We present a fully distributed key management mechanism for the first scheme, and solve the redaction-misuse problem which remains in blockchains using Ateniese et al.’s generic framework. We also suggest the voting strategy when applying our second scheme. Finally, we show how to efficiently integrate our chameleon hash with any blockchain technologies, with only minor changes to the current blockchains in use. For extend interests, our proposed chameleon hash functions are also suitable for constructing quantum-resistant chameleon signatures and off-line/on-line signatures.

A Quantum Resistant Chameleon Hashing and Signature Scheme

ABSTRACTChameleon signatures introduced by Krawczyk and Rabin are based on well-established hash-and-sign paradigm. It is a non-interactive signature scheme that simultaneously provides the properties of non-transferability and non-repudiation. The chameleon hash function is a trapdoor one-way function which prevents everyone except the holder of the trapdoor information from computing collision on a message digest. The chameleon signature scheme achieves non-transferability as the recipient of the signature is the holder of the trapdoor information. He could be able to compute collision on the hash value and hence no third party could be able to identify the real signer. In the initial constructions of chameleon signature schemes, the occurrences of collisions expose the secret key of the recipient. This strongly prevents the recipient to compute hash collisions, partially undermining the concept of non-transferability. Hence it is important to overcome this key exposure problem, and its aligned problems of key revocation and key redistribution. Also the existing chameleon signature schemes are based on the hard problems in number theory such as integer factorization or the discrete log problem over various groups. The construction of a large-scale quantum computer would render insecurity to these schemes. Hence as recommended by NISTIR 8105, we propose a quantum resistant chameleon hashing and signature scheme based on hard problems in coding theory. The scheme also satisfies the security properties of chameleon signature, such as collision resistance, semantic security, key exposure freeness, non-transferability and unforgeability. As code-based cryptosystem is an important candidate of postquantum cryptosystem, the proposed code-based chameleon signature scheme would be a promising alternative to the number theoretic based schemes. In addition, we also propose a method to transform the code-based chameleon hashing scheme into an ordinary signature scheme and prove its unforgeability in the random oracle model.

DNS/DANE Collision-Based Distributed and Dynamic Authentication for Microservices in IoT †.

IoT devices provide real-time data to a rich ecosystem of services and applications. The volume of data and the involved subscribe/notify signaling will likely become a challenge also for access and core networks. To alleviate the core of the network, other technologies like fog computing can be used. On the security side, designers of IoT low-cost devices and applications often reuse old versions of development frameworks and software components that contain vulnerabilities. Many server applications today are designed using microservice architectures where components are easier to update. Thus, IoT can benefit from deploying microservices in the fog as it offers the required flexibility for the main players of ubiquitous computing: nomadic users. In such deployments, IoT devices need the dynamic instantiation of microservices. IoT microservices require certificates so they can be accessed securely. Thus, every microservice instance may require a newly-created domain name and a certificate. The DNS-based Authentication of Named Entities (DANE) extension to Domain Name System Security Extensions (DNSSEC) allows linking a certificate to a given domain name. Thus, the combination of DNSSEC and DANE provides microservices’ clients with secure information regarding the domain name, IP address, and server certificate of a given microservice. However, IoT microservices may be short-lived since devices can move from one local fog to another, forcing DNSSEC servers to sign zones whenever new changes occur. Considering DNSSEC and DANE were designed to cope with static services, coping with IoT dynamic microservice instantiation can throttle the scalability in the fog. To overcome this limitation, this article proposes a solution that modifies the DNSSEC/DANE signature mechanism using chameleon signatures and defining a new soft delegation scheme. Chameleon signatures are signatures computed over a chameleon hash, which have a property: a secret trapdoor function can be used to compute collisions to the hash. Since the hash is maintained, the signature does not have to be computed again. In the soft delegation schema, DNS servers obtain a trapdoor that allows performing changes in a constrained zone without affecting normal DNS operation. In this way, a server can receive this soft delegation and modify the DNS zone to cope with frequent changes such as microservice dynamic instantiation. Changes in the soft delegated zone are much faster and do not require the intervention of the DNS primary servers of the zone.

Building Redactable Consortium Blockchain for Industrial Internet-of-Things

Applying consortium blockchain as a trust layer for heterogeneous industrial Internet-of-Things devices is cost-effective. However, with an increase in computing power, some powerful attacks (e.g., the 51% attack) are inevitable and will cause severe consequences. Recent studies also confirm that anonymity and immutability of blockchain have been abused to facilitate black market trades, etc. To operate controllable blockchain for IIoT devices, it is necessary to rewrite blockchain history back to a normal state once the chain is breached. Ateniese et al. proposed redactable blockchain by using chameleon hash (CH) to replace traditional hash function, it allows blockchain history to be written when needed (EuroSP (2) update the signatures accordingly to authenticate the redacted contents; (3) satisfy the low-computing need of the individual IIoT device. In this paper, we overcome the above issues by proposing the first threshold chameleon hash (TCH) and accountable-and-sanitizable chameleon signature (ASCS) schemes. Based on them, we build a redactable consortium blockchain which is efficient for IIoT devices to operate. It allows a group of authorized sensors to write and rewrite blockchain without causing any hard forks. Basically, TCH is the first TCH and ASCS is a public-key signature supporting file-level and block-level modifications of signatures without impairing authentications. Additionally, ASCS achieves accountability to avoid abuse of redaction. While security analysis validates our proposals, the simulation results show that redaction is acceptably efficient if it is executed at a small scale or if we adopt a coarse-grained redaction while sacrificing some securities.

Improved generic construction of chameleon hash to group elements

ABSTRACTChameleon hash functions are trapdoor one-way functions with many applications as, for example, off-line/on-line signatures and chameleon signatures. Chameleon signatures are useful to protect privacy of signatures in some business systems where signatures are not allowed to be verified universally, and off-line/on-line signatures are particularly suitable for systems with limited computing resources on-line, but enough computation power off-line, such as in smart card applications. Previous research focused on concrete constructions based on different assumptions, as well as schemes without the key-exposure problem. The main contribution of this paper is a generic construction method of structure-preserving chameleon hash from quasi-adaptive noninteractive zero-knowledge (QANIZK) and two concrete constructions from adaptive sound and simulation sound QANIZK for witness sampleable (WS) distributions proposed by Kiltz and Wee in Eurocrypt 2015, with/without key-exposure respectively. Compared with the constructions from linearly homomorphic structure-preserving signature (LHSPS), our constructions improve the efficiency, the assumptions, as well as the security guarantees.

ID-BASED CHAMELEON HASHING AND CHAMELEON SIGNATURE BASED ON GQ SCHEME

In this manuscript, we propose key-exposure free chameleon hash and chameleon signature scheme in the framework of Guillou-Quisquater (GQ) scheme (9). This scheme provides more flexible construction of efficient key- exposure free chameleon hash and signature scheme. Moreover, one benefit of consequential the chameleon signature scheme is that the property of message hiding or message realization can be achieved without obstacle by the signer, i.e., the signer can efficiently prove which message was the original one if he desires. The proposed scheme presented in this article improve and extend the corresponding schemes of others several authors. It is also implemented in Mathematica 7.0.

English

English

New Identity-based Key-exposure Free Chameleon Hash from Bilinear Pairings

Chameleon signatures are based on the well established hash-and-sign paradigm, where a chameleon hash function is used to compute the cryptographic message digest. Chameleon signatures simultaneously provide the properties of non-repudiation and non-transferability for the signed message. However, the initial constructions of chameleon signatures suffer from the problem of key exposure of chameleon hashing. Recently, some specific constructions of key-exposure free chameleon hashing are presented in the setting of certificate-based systems, but few works are done in identity-based systems. In this paper, we first analyse the hierarchical identity-based chameleon hash (HIBCH) and key-exposure free identity-based chameleon hash schemes (IBCH) proposed by Bao et al. in 2011 and then propose two improved schemes from bilinear pairings, with the idea of hierarchical key distribution. Moreover, we analyse the security and efficiency of our proposed schemes.

Efficient Design of Certificateless Chameleon Signature from Bilinear Pairing

Certificateless public key cryptography (CL-PKC), does not require the use of the certificate to guarantee the authenticity of public keys. It does rely upon the use of a trusted third party (TTP), who is in possession of a master key. CL-PKC does not suffer from the key escrow property. Thus, CL-PKC can be seen as a model for the use in public key cryptography. In this paper, we proposed a new certificateless Chameleon signature scheme based on bilinear pairings. The proposed scheme is more efficient than AL-Riyami and Pateson [10] schemes. And our scheme is un-forgeable under the hardness assumption of the q-strong Diffie-Hellman problem and Computational Diffie-Hellman problem.

Identity-based chameleon hashing and signatures without key exposure

The notion of chameleon hash function without key exposure plays an important role in designing secure chameleon signatures. However, all of the existing key-exposure free chameleon hash schemes are presented in the setting of certificate-based systems. In 2004, Ateniese and de Medeiros questioned whether there is an efficient construction for identity-based chameleon hashing without key exposure.In this paper, we propose the first identity-based chameleon hash scheme without key exposure based on the three-trapdoor mechanism, which provides an affirmative answer to the open problem. Moreover, we use the proposed chameleon hash scheme to design an identity-based chameleon signature scheme, which achieves all the desired security properties.

A Characterization of Chameleon Hash Functions and New, Efficient Designs

This paper shows that chameleon hash functions and Sigma protocols are equivalent. We provide a transform of any suitable Sigma protocol to a chameleon hash function, and also show that any chameleon hash function is the result of applying our transform to some suitable Sigma protocol. This enables us to unify previous designs of chameleon hash functions, seeing them all as emanating from a common paradigm, and also obtain new designs that are more efficient than previous ones. In particular, via a modified version of the Fiat–Shamir protocol, we obtain the fastest known chameleon hash function with a proof of security based on the standard factoring assumption. The increasing number of applications of chameleon hash functions, including on-line/off-line signing, chameleon signatures, designated-verifier signatures and conversion from weakly-secure to fully-secure signatures, make our work of contemporary interest.

Discrete logarithm based chameleon hashing and signatures without key exposure

Chameleon signatures simultaneously provide the properties of non-repudiation and non-transferability for the signed message. However, the initial constructions of chameleon signatures suffer from the key exposure problem of chameleon hashing. This creates a strong disincentive for the recipient to compute hash collisions, partially undermining the concept of non-transferability. Recently, some constructions of discrete logarithm based chameleon hashing and signatures without key exposure are presented, while in the setting of gap Diffie–Hellman groups with pairings. In this paper, we propose the first key-exposure free chameleon hash and signature scheme based on discrete logarithm systems, without using the gap Diffie–Hellman groups. This provides more flexible constructions of efficient key-exposure free chameleon hash and signature schemes. Moreover, one distinguishing advantage of the resulting chameleon signature scheme is that the property of “message hiding” or “message recovery” can be achieved freely by the signer, i.e., the signer can efficiently prove which message was the original one if he desires.

Designated-Verifier Chameleon Proxy Signature

With the development of computer technology, the requirement of the methods to verify the authenticity, the validity, and the integrity of information is becoming much bigger. For this purpose, many methods have been generated, such as digital signature, digital watermarking, steganography, and so on. Digital signature is a hot topic in cryptography and it plays a very important role in many fields. A normal digital signature allows a signer to generate a signature of the message with his secret key and the generated signature can be verified by anyone with the signer's public key. Chameleon signature is a non-interactive signature based on the well-established hash-and-sign paradigm, in which the receiver cannot convince the third party of the identity of the signer. Designated-verifier signature is a very useful tool for protecting the privacy of the valid verifier. Motivated by above statements, we construct a new chameleon hash scheme and construct a new DVICPS scheme. Our chameleon hash scheme satisfies all the properties of the normal chameleon hash function. In our hash function the owner of a public key does not need to retrieve the associated secret key. We prove that our new chameleon hash scheme satisfies all the attributes defined in [1] and our chameleon hash scheme is secure assuming Weak Computational Diffie-Hellman (WCDH) assumption is difficult. And we show our chameleon hash scheme is secure based on the difficulty of solving WCDHP assumption. Moreover, we use the proposed chameleon hash function to design a designated-verifier ID-based chameleon proxy signature (DVICPS) scheme. Furthermore, we analyze the security of our DVICPS scheme and prove that our DVICPS scheme is secure in the random oracle model. In our signature scheme, only the receiver who owns the corresponding secret key can verify the validity of the signature which efficiently protects the benefit of the verifier. We also prove that our signature scheme is secure in random oracle model. The success probability of forging our DVICPS scheme is equivalent to solving Computational Diffie-Hellman Problem (CDHP). Thus, our DVICPS scheme is secure and efficient.