Existential Unforgeability Research Articles

Dynamic-FROST: Schnorr threshold signatures with a flexible committee

Abstract Threshold signatures enable any subgroup of predefined cardinality t t out of a committee of n n participants to generate a valid, aggregated signature. Although several ( t , n ) \left(t,n) -threshold signature schemes exist, most of them assume that the threshold t t and the set of participants do not change over time. Practical applications of threshold signatures might benefit from the possibility of updating the threshold or the committee of participants. Examples of such applications are consensus algorithms and blockchain wallets. In this article, we present Dynamic-FROST (D-FROST) that combines FROST, a Schnorr threshold signature scheme, with CHURP, a dynamic proactive secret sharing scheme. The resulting protocol is the first Schnorr threshold signature scheme that accommodates changes in both the committee and the threshold value without relying on a trusted third party. Besides detailing the protocol, we present a proof of its security: as the original signing scheme, D-FROST preserves the property of existential unforgeability under chosen-message attack.

Efficient Threshold Attribute-Based Signature Scheme for Unmanned Aerial Vehicle (UAV) Networks

Unmanned aerial vehicles (UAVs) are highly versatile and cost-effective, making them an attractive option for various applications. In UAV networks, it is essential to implement a digital signature scheme to ensure the integrity and authentication of commands sent to UAVs. Moreover, this digital signature scheme not only maintains the real-time performance of UAVs while executing commands but also protects the identity privacy of the signer. To meet these needs, we propose an efficient threshold attribute-based proxy signature (t-ABPS) scheme that integrates a threshold predicate specifically designed for UAV networks. The formal security proof for the t-ABPS scheme demonstrates its existential unforgeability under selective-attribute and chosen-message attacks (EUF-sA-CMA) in the random oracle model. This scheme also ensures the identity privacy of the signer. Furthermore, we evaluate the computational costs and communication costs associated with the proposed scheme. Our analysis indicates that the t-ABPS scheme is more computationally efficient than other existing attribute-based proxy signature schemes, but it has higher communication costs.

An Efficient Lattice‐Based Heterogeneous Signcryption Scheme for VANETs

ABSTRACTNowadays, vehicular ad‐hoc networks (VANETs) offer increased convenience to drivers and enable intelligent traffic management. However, the public wireless transmission channel in VANETs brings challenges related to security vulnerabilities and privacy leakage, in addition, vehicles produced by different manufacturers may use different cryptosystems such as certificateless cryptosystems (CLCs) and identity‐based cryptosystems (IBC). To address privacy leakage during cross‐cryptosystem communication in VANETs, we propose a lattice‐based heterogeneous signcryption scheme named LHS‐C2I. The scheme facilitates secure multi‐cryptosystem bidirectional communication as CLC‐based vehicles to IBC‐based vehicles and IBC‐based vehicles to CLC‐based vehicles. The confidentiality and authenticity of LHS‐C2I help to prevent the users from privacy leakage during cross‐cryptosystem communication and to authenticate the message integrity and the sender's identity legitimacy. The proposed scheme is proven to achieve Indistinguishability under Chosen Ciphertext Attack (IND‐CCA2) and Existential Unforgeability against Adaptive Chosen Messages Attack (EUF‐CMA) within the random oracle model. Performance analysis demonstrates that LHS‐C2I outperforms existing schemes in terms of computational overhead, communication overhead, and overall security features. It is particularly well‐suited for scenarios requiring secure communication across different cryptosystems in VANETs.

Existential unforgeability in quantum authentication from quantum physical unclonable functions based on random von Neumann measurement

Physical unclonable functions (PUFs) leverage inherent, nonclonable physical randomness to generate unique input-output pairs, serving as secure fingerprints for cryptographic protocols like authentication. Quantum PUFs (QPUFs) extend this concept by using quantum states as input-output pairs, offering advantages over classical PUFs, such as challenge reusability via public channels and eliminating the need for trusted parties due to the no-cloning theorem. Recent work introduced a generalized mathematical framework for QPUFs. It was shown that random unitary QPUFs cannot achieve existential unforgeability against quantum polynomial time (QPT) adversaries. Security was possible only with additional uniform randomness. To avoid the cost of external randomness, we propose a novel measurement-based scheme. Here, the randomness naturally arises from quantum measurements. Additionally, we introduce a second model where the QPUF functions as a nonunitary quantum channel, which guarantees existential unforgeability. These are the first models in the literature to demonstrate a high level of provable security. Finally, we show that the quantum phase estimation (QPE) protocol, applied to a Haar random unitary, serves as an approximate implementation of the second type of QPUF by approximating a von Neumann measurement on the unitary's eigenbasis. Published by the American Physical Society 2024

Enhancing Efficiency in Trustless Cryptography: An Optimized SM9-Based Distributed Key Generation Scheme.

Intelligent systems are those in which behavior is determined by environmental inputs, and actions are taken to maximize the probability of achieving specific goals. Intelligent systems are widely applied across various fields, particularly in distributed intelligent systems. At the same time, due to the extensive interaction with user data, intelligent systems face significant challenges regarding security. This study proposes an optimized distributed key generation (DKG) scheme for identity-based cryptography (IBC) using the SM9 standard. Our scheme introduces a (t, n)-threshold system that functions without a trusted center, addressing the vulnerability of single points of failure in conventional key generation centers (KGCs). We reduce communication and computational demands by refining the Paillier share transformation protocol, ensuring efficient, centerless operations. The scheme's security, validated in the existential unforgeability against adaptive chosen identity attacks (EUF-CIA) model, demonstrates its practical applicability and enhanced security for distributed intelligent systems.

Privacy enhanced secure compact attribute-based signature from MQ problem for monotone span program

Privacy enhanced secure compact attribute-based signature from MQ problem for monotone span program

LB-CLAS: Lattice-based conditional privacy-preserving certificateless aggregate signature scheme for VANET

LB-CLAS: Lattice-based conditional privacy-preserving certificateless aggregate signature scheme for VANET

Efficient Authentication Steps for Vehicle Transmission in Ad-Hoc Networks

Vehicular ad-hoc networks (VANETs) are underactive development, thanks in part to recent advances in wireless communication and networking technologies. The most fundamental part of VANET is to enable message authentications between vehicles and roadside units. Message authentication using proxy vehicles has been proposed to reduce the computational overhead of roadside units significantly. In this message authentication scheme, a proxy vehicle that verifies multiple messages at the same time improves roadside units’ efficiency. In this paper first, we show that the only proxy-based authentication scheme (PBAS) presented for this goal by Liu et al. cannot guarantee message authenticity and also it is not resistant to impersonation and modification attacks and false acceptance of batched invalid signatures. Next, we propose a new identity-based message authentication scheme using proxy vehicles (ID-MAP). Then guarantee that it can satisfy the message authentication requirements, existential unforgeability of underlying signatures against adaptability chosen message, and identity attack is proved under the Elliptic Curve discrete logarithm problem (ECDLP) in the random oracle model. It should be highlighted that ID MAP not only is more efficient than PBAS since it is pairing-free and identity based and also it does not use map-to-point hash functions, also, it satisfies the security and privacy requirements of VANETs. Furthermore, analysis shows that the required time to verify 3000 messages in ID-MAP is reduced by 76% compared to that PBAS.

Comment on “An efficient identity-based signature scheme with provable security”

Comment on “An efficient identity-based signature scheme with provable security”

Enhancing Security in Smart Renewable Energy Grids Through Proxy Signcryption Approach

The rapid development of smart renewable energy grids (SREGs) has resulted in a vast amount of data that requires efficient access control and secure mechanisms for sharing energy records among stakeholders. This paper proposes a novel approach called the identity‐based proxy signcryption‐based scheme for SREGs (ID‐PSC‐SREGs), which ensures the secure sharing of energy records in SREGs. The ID‐PSC‐SREG scheme integrates the benefits of signature and encryption techniques, merging them into a unified algorithm and providing a comprehensive solution for the confidentiality and authenticity of energy records. Extensive security analysis demonstrates that the scheme achieves provable security against adaptive chosen ciphertext attacks (IND‐ID‐PSC‐SREG‐CCA2) and existential unforgeability against adaptive chosen message attacks (EUF‐ID‐PSC‐SREG‐CMAs) under the decisional Diffie–Hellman problem. In order to further ascertain the security of the ID‐PSC‐SREG scheme, formal verification utilizing the automated validation of internet security protocols and applications (AVISPAs) is performed. The results confirm the scheme’s safety under the On‐the‐Fly Model‐Checker (OFMC) and Constraint Logic‐based Attack Searcher (CL‐AtSe).

A lightweight attribute-based signcryption scheme based on cloud-fog assisted in smart healthcare.

In the environment of big data of the Internet of Things, smart healthcare is developed in combination with cloud computing. However, with the generation of massive data in smart healthcare systems and the need for real-time data processing, traditional cloud computing is no longer suitable for resources-constrained devices in the Internet of Things. In order to address this issue, we combine the advantages of fog computing and propose a cloud-fog assisted attribute-based signcryption for smart healthcare. In the constructed "cloud-fog-terminal" three-layer model, before the patient (data owner)signcryption, it first offloads some heavy computation burden to fog nodes and the doctor (data user) also outsources some complicated operations to fog nodes before unsigncryption by providing a blinded private key, which greatly reduces the calculation overhead of resource-constrained devices of patient and doctor, improves the calculation efficiency. Thus it implements a lightweight signcryption algorithm. Security analysis confirms that the proposed scheme achieves indistinguishability under chosen ciphertext attack and existential unforgeability under chosen message attack if the computational bilinear Diffie-Hellman problem and the decisional bilinear Diffie-Hellman problem holds. Furthermore, performance analysis demonstrates that our new scheme has less computational overhead for both doctors and patients, so it offers higher computational efficiency and is well-suited for application scenarios of smart healthcare.

Practical NTRU Signcryption in the Standard Model.

Based on the NTRU trapdoor used in NIST's Falcon, a signcryption scheme following the sign-then-encrypt paradigm is constructed. The existing partitioning technique based on Waters hash over the lattice can not complete the security reduction in the standard model for the signature part due to the "partiality" of the pre-image generated with the NTRU trapdoor. To address this, a variant of Waters hash over small integers is proposed and, the probability of the successful reduction is analyzed. The resulting signcryption achieves existential unforgeability under the adaptive chosen-message attacks. By utilizing the uniqueness of the secret and the noise in an NTRU instance, the tag used in encryption is eliminated. Furthermore, a method to construct tamper-sensitive lattice public key encryption is proposed. This approach implants the ciphertext-sensitive information into the lattice public key encryption and binds it to the encrypted information. The malleability to the public key ciphertext triggers the change of the message-signature pair so that the IND-CCA2 security of the entire ciphertext can be guaranteed by the signature for the message. Thanks to the rational design and the efficiency of the NTRU trapdoor, the computational overhead of the proposed scheme is reduced significantly compared to the existing lattice-based signcryption scheme, reaching orders of magnitude improvement in efficiency. The experiment shows that the proposed scheme is efficient.

Provably secure multi-signature scheme based on the standard SM2 signature scheme

Provably secure multi-signature scheme based on the standard SM2 signature scheme

An Efficient Certificateless Signature Scheme With Provably Security and Its Applications

The Internet of Things (IoT) is helpful in making people's life more convenient and efficient. To ensure that the nodes within IoT can interact securely, a certificateless signature (CLS) can be used to protect message authentication in the IoT. Recently, some concrete constructions of CLS schemes have been proposed in the literature, but through our analyses, we demonstrate that some existing CLS schemes cannot keep their claimed security because of various security flaws. For example, a valid signature can be forged by any Type I adversary by replacing the corresponding user's public key. In this article, we describe the security flaws that need to be addressed and introduce a novel CLS scheme without using bilinear mapping. The existential unforgeability in our proposed scheme can be proved based on the hardness of the elliptic curve discrete logarithm problem in the random oracle model. The comparison with existing CLS schemes shows that our scheme not only enjoys more security features but also is more efficient in computation. Moreover, we introduce an identity authentication protocol as the application of our proposed CLS scheme, which achieves mutual authentication and anonymity in communications.

Attribute-Based Proxy Signature Scheme Supporting Flexible Threshold Predicate for UAV Networks

Unmanned aerial vehicle (UAV) is an attractive application because of its flexibility and economy. It may use a digital signature scheme to protect commands sent to UAVs. Moreover, the digital signature scheme should guarantee the real-time performance of UAVs executing commands and protect the signer’s privacy. Therefore, we proposed an attribute-based proxy signature (ABPS) scheme supporting flexible threshold predicate for UAV networks and proved its security. It has existential unforgeability under selective-predicate and chosen message attacks (EUF-sP-CMA) and can protect the signer’s privacy. We analyzed its computation costs based on experimental data and communication costs. The analysis results indicate that our ABPS scheme has less computation costs than other ABPS schemes and is at the same level as other ABPS schemes on communication costs.

Lattice-Based Threshold Signcryption for Blockchain Oracle Data Transmission

Threshold signature can solve the problems of high cost and network congestion during the execution of smart contracts. However, the information transmitted in public links is vulnerable to eavesdropping, tampering and other network attacks, it is essential to ensure the confidentiality and integrity during data transmission. However, traditional threshold signcryption is not suitable for blockchain setting and cannot withstand the quantum computing attacks. In view of these reasons, one lattice-based threshold signcryption for blockchain oracle data transmission (BCODT-LTSC) is devised in this article. BCODT-LTSC satisfies the existential unforgeability, confidentiality and threshold characteristic; it has very low computation cost and is suitable for the application in blockchain scenario.

Revocable Signature Scheme with Implicit and Explicit Certificates.

This paper addresses the certificate revocation problem and proposes the first revocable pairing-based signature scheme with implicit and explicit certificates (IE-RCBS-kCAA). We should no longer discuss whether to revoke certificates but how to do it effectively, ensuring both the scalability of the revocation operation and the non-repudiation of the signature in the short or long term. Under the computational difficulty assumptions of the modified collusion attack algorithm with k traitors (k-mCAA) and discrete logarithm (DL) problems, we demonstrate that our scheme is secure against existential unforgeability under chosen message attacks (EUF-IERCBS-kCAA-CMA) in a random oracle model. The proposed solution is scaled and allows the use of many trusted status authorities that issue explicit short-term certificates confirming the validity of explicit long-term certificates. Furthermore, we demonstrate that our signature scheme has a short-term non-repudiation property for the shell validity model.

TFS-ABS: Traceable and Forward-Secure Attribute-Based Signature Scheme With Constant-Size

Attribute-based signature (ABS) is a versatile and useful cryptogrammic technology. In an ABS scheme, every signer is distributed a signing secret key in term of her/his attributes, and endorses a message in relation to some signing policy fulfilled by the signer's attributes. The verifier checks that the signature is indeed endorsed by the signer whose attributes match with the signing policy. However, existing ABS schemes suffer from the issue of abusing signature and key exposure. To address the above issues, we provide a traceable and forward-secure attribute-based signature (TFS-ABS) scheme with constant-size supporting flexible threshold predicates. Furthermore, we prove that the presented TFS-ABS scheme is existential unforgeability against selective predicate attack under the standard model. We reduce the security for the provided scheme to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$q$</tex-math></inline-formula> -Diffie-Hellman exponentiation assumption. The designed scheme can be used to alleviate the damage induced by key exposure and traces the real identity of signer by attribute authority (AA) when the signer occurs abusing behavior. Furthermore, the signature size in presented scheme keeps constant and is independent of the number of attributes. Experimental evaluations exhibit that the presented TFS-ABS scheme is efficient in term of the communication and computation overhead.

Blockchain-assisted certificateless signcryption for vehicle-to-vehicle communication in VANETs

Blockchain-assisted certificateless signcryption for vehicle-to-vehicle communication in VANETs

EBiBa: A Post-Quantum Hash-Based Signature With Small Signature Size in the Continuous Communication of Large-Scale Data

Abstract We present eBiBa (enhanced BiBa), a hash-based signature scheme with the smallest possible signature size, while ensuring high feasibility and security in a specific application model. Our scheme is tailored to address the communication requirement of a large-scale public data stream continuously disseminated between two participants while ensuring data source and data integrity authentication. To achieve these goals, firstly, we optimized the classical hash tree mode into a hybrid mode to efficiently perform public key authentication and eliminate the need for an authenticated channel to transmit large amounts of data, unlike the initial BiBa-based broadcast authentication protocol. Secondly, we employed a specific tweakable hash chain function to digest a batch of messages, reducing the required conditions for post-quantum existential unforgeability under adaptive chosen message attack (EUCMA) of eBiBa to a second-pre-image-resistance-like property instead of collision resistance. This results in reduced pre-computation in both key and signature generations. Thirdly, we utilized a forward-secure pseudorandom function to achieve forward-secure of the proposed scheme. Finally, we minimize the signature size through a series of procedures. Firstly, we select BiBa few-time signature as the underlying signature scheme since it is currently the few-time hash-based signature with the smallest signature size that we are aware of; in addition, the hybrid approach we employed can also significantly reduce the signature size compared to using a hash tree solely; for the hash tree structure, we design a specific authentication path in combination with the related communication model to further minimize the signature size; finally, we optimize the authentication approach to achieve the minimum signature size in a single transmission. Our construction minimizes the signature size in the aforementioned model, achieving a compression rate of 0.017 to 0.828 based on distinct values of parameters, as compared to XMSS-256. We also demonstrated that eBiBa can achieve post-quantum forward-secure and EUCMA security.