Linkable Ring Signature Scheme Research Articles

Linkable ring signature scheme with stronger security guarantees

Ring signatures enable a user to sign messages on behalf of an arbitrary set of users, called the ring. The signer-anonymity property guarantees that the signature does not reveal which member of the ring signed the message. The notion of linkable ring signatures (LRS) is an extension of the concept of ring signatures such that there is a public way of determining whether two signatures have been produced by the same signer. However, the existing LRS schemes may not be competent in some scenarios since they exhibit a gap to bridge as reflected on the security guarantees such as the absence of quantum-resistance, inadequate security notions, and a reliance on the random oracle heuristic.In this paper, we present a framework for LRS that provides stronger security guarantees. We instantiate the framework from standard lattice assumptions and prove the security in the standard model. Furthermore, we implement our scheme and conduct experimental evaluations, which demonstrate that the performances are practical for typical settings.

Quantum-Secure Hybrid Blockchain System for DID-Based Verifiable Random Function with NTRU Linkable Ring Signature

In this study, we present a secure smart contract-based Verifiable Random Function (VRF) model, addressing the shortcomings of existing systems. As quantum computing emerges, conventional public key cryptography faces potential vulnerabilities. To enhance our VRF’s robustness, we employ post-quantum Ring-LWE encryption for generating pseudorandom sequences and a NTRU lattice-based linkable ring signature scheme. Given the computational intensity of this approach and associated on-chain gas costs, we propose a hybrid architecture of VRF system where both on-chain and off-chain can communicate in a scalable and secure way. Our decentralized VRF employs multi-party computation (MPC) with blockchain-based decentralized identifiers (DID), ensuring the collective efforts of enhanced randomness and security. We show the security and privacy advantages of our proposed VRF model with the approximated estimation of overall temporal and spatial complexities. We also evaluate our VRF MPC model’s entropy and outline its Solidity smart contract integration. This research also provides a method to produce and verify the VRF output’s proof, optimal for scenarios necessitating randomness and validation. Lastly, using NIST SP800-22 test suite for randomness, we demonstrate the commendable result with a 97.73% overall pass rate on 11 standard tests and 0.5459 of average 𝑝-value for the total 176 tests.

New trend for LWE application in different computer science fields

Problems of large keys in the on-lattice ring signature link due to reduce to the lattice, based on the problem of fault-tolerant learning on the ring (RLWE), according to "Homomorphic Commitment→∑-Protocol→Fiat-Shamir Transformation" reconstructs a linkable ring signature scheme on a lattice. First construct a base “Homomorphic commitment scheme” on polynomial ring of RLWE difficult, and use the Fiat-Shamir transformation method. The method converts the ∑-protocol into a linkable ring signature scheme, and suggests linkable ring signature scheme model. It is resistant to quantum computer attacks. compared with the previous linkable ring signature schemes on lattices, proposed methods with high computational, simple and less time frame because the ring elements in the scheme are taken from small polynomials which represents as case of application in computer science.

An Efficient Multilayered Linkable Ring Signature Scheme With Logarithmic Size for Anonymous Payment in Vehicle-to-Grid Networks

Vehicle-to-Grid (V2G) networks are emerging as an outstanding technique for alleviating energy and environmental concerns. Whereas, malicious attackers thirst for private information from frequent electricity/service exchanges between electric vehicles (EVs) and smart grids (SG) in V2G networks. Several attempts have been made to use ring signatures to achieve privacy-preserving payment and ensure reliable services in V2G. Nevertheless, most of the existing ring signature-based payment proposals may still have numerous limitations in the V2G paradigm due to their heavy signature size. To address the aforementioned problem, we propose Emularis, an efficient multilayered linkable ring signature scheme with a logarithmic size. Specifically, we implement an anonymous payment scheme for V2G using Emularis. We then prove that Emularis guarantees security and privacy requirements through rigorous security analysis. Furthermore, our scheme significantly outperforms existing schemes in terms of communication and computation costs. Extensive experimental results indicate that our scheme is suitable for deployment in V2G security-related applications.

Supersingular Isogeny-based Ring Signature

The increasing demand for secure and anonymous transactions raises the popularity of ring signatures, which is a digital signature scheme that allows identifying a group of possible signers without revealing the identity of the actual signer. This paper presents efficient supersingular isogeny-based ring signature and linkable ring signature schemes that will find potential applications in post-quantum technologies. We develop the ring signature scheme by applying the Fiat-Shamir transform on the sigma protocol for a ring which we obtain from the supersingular isogeny-based interactive zero-knowledge identification scheme by adopting the scheme for a ring. We also extend our ring signature protocol with an additional parameter, i.e., a tag that provides to detect if a signer issues two signatures concerning the same ring by preserving anonymity and linkable anonymity. The signature size of our ring signature protocols increases logarithmically in the size of the ring thanks to the Merkle trees. We show the security proofs and efficiency analyses of the protocols offered. Moreover, we provide the implementation results of the supersingular isogeny-based ring signature, which offers small signature sizes for NIST post-quantum security levels.

On The Impossibility of Providing Strong Anonymity in Blockchains via Linkable Ring Signatures

<p>Anonymity is a necessary property for a ring signature scheme and also its variant such as linkable ring signature and traceable ring signature schemes, which are especially useful in blockchains. Intuitively, those variants were designed for detecting or seeking the dishonest signatory, however, at the cost of reducing the anonymity of a traditional ring signature. As a result, while various constructions of strongly anonymous ring signatures were well-known, a linkable ring signature scheme with the same property was an open problem for a long time. In this work, we launched a so-called denying attack to show the gap between an arbitrary ring signature and linkable ring signature transparently, which further confirmed the widely believed impossibility in building a linkable ring signature with both strong anonymity and strong linkability. For a concrete instance, we also applied this attack to the scheme in IEEE TKDE, which to the best of our knowledge is the unique linkable ring signature both with strong anonymity and strong linkability so far. The concrete attack is easily launched in blockchain so that it shows the impossibility of providing strong anonymity via linkable ring signature for blockchain applications, since strong likability is indispensable.</p> <p> </p>

A Novel Linkable Ring Signature on Ideal Lattices

In this paper, a novel linkable ring signature scheme is constructed. The hash value of the public key in the ring and the signer's private key are based on random numbers. This setting makes it unnecessary to set the linkable label separately for our constructed scheme. When judging the linkability, it is necessary to determine whether the number of the intersections of the two sets reaches the threshold related to the number of the ring members. In addition, under the random oracle model, the unforgeability is reduced to the SVPγ problem. The anonymity is proved based on the definition of statistical distance and its properties.

AQRS: Anti-quantum ring signature scheme for secure epidemic control with blockchain

Epidemics, such as Corona Virus Disease 2019 (COVID-19), have serious consequences globally, of which the most effective way to control the infection is contact tracing. Nowadays, research related to privacy-preserving epidemic infection control has been conducted, nevertheless, current researchers do not regard the authenticity of records and infection facts as well as poor traceability. Moreover, with the emergence of quantum computing, there is a bottleneck in upholding privacy, security and efficiency. Our paper proposes a privacy-preserving epidemic infection control scheme through lattice-based linkable ring signature in blockchain, called AQRS. Firstly, our scheme adopts a blockchain with three ledgers to store information in a distributed manner, which offers transparency and immunity from the Single Point of Failure (SPoF) and Denial of Service (DoS) attacks. Moreover, we design a lattice-based linkable ring signature scheme to secure privacy-preserving of epidemic infection control. Significantly, we are the first to introduce the lattice-based linkable ring signature into privacy preserving in epidemic control scenario. Security analysis indicates that our scheme ensures unconditional users anonymity, record unforgeability, signature linkability, link non-slanderability and contact traceability. Finally, the comprehensive performance evaluation demonstrates that our scheme has an efficient time-consuming, storage consumption and system communication overhead and is practical for epidemic and future pandemic privacy-preserving.

Stateless forward-secure key-insulated linkable ring signature scheme in ID-based setting

Forward-security and key-insulation have been the mainstream antidotes to the key exposure problem in conventional and ring signatures primarily in the setting of public key infrastructure. However, all extant schemes require keeping state of time periods. Moreover, time-bound keys are stored for retrieval during key update and more importantly signature-related dispute resolution which may extend beyond stipulated time periods. Spurred on by the gravity of key exposure in the setting of identity-based cryptography, we introduce a stateless forward-secure key-insulated linkable ring signature accomplished partly with on-demand ephemeral secret keys consequently eliminating the need for state-keeping and long-term storage. We prove security of our construction in the Random Oracle Model based on intractable problems of Computational Diffie–Hellman (CDH) and Discrete Logarithm (DL). Subsequently, we present evaluation results from a comparative analysis of extant identity-based linkable ring signature schemes to attest to the uniqueness, convenience and efficiency of our scheme which incidentally compared to state-of-the-art achieves a running time of 22.113ms faster at verification phase making it the fastest compared to extant schemes aside the statelessness and constant linkability attributes.

Efficient Linkable Ring Signature Scheme over NTRU Lattice with Unconditional Anonymity.

In cloud and edge computing, senders of data often want to be anonymous, while recipients of data always expect that the data come from a reliable sender and they are not redundant. Linkable ring signature (LRS) can not only protect the anonymity of the signer, but also detect whether two different signatures are signed by the same signer. Today, most lattice-based LRS schemes only satisfy computational anonymity. To the best of our knowledge, only the lattice-based LRS scheme proposed by Torres et al. can achieve unconditional anonymity. But the efficiency of signature generation and verification of the scheme is very low, and the signature length is also relatively long. With the preimage sampling, trapdoor generation, and rejection sampling algorithms, this study proposed an efficient LRS scheme with unconditional anonymity based on the e-NTRU problem under the random oracle model. We implemented our scheme and Torres et al.'s scheme, as well as other four efficient lattice-based LRS schemes. It is shown that under the same security level, compared with Torres et al.'s scheme, the signature generation time, signature verification time, and signature size of our scheme are reduced by about 94.52%, 97.18%, and 58.03%, respectively.

A Hybrid Design of Linkable Ring Signature Scheme with Stealth Addresses

Blockchain is a transformational technology which affects finance, Internet, and politics. However, many privacy protection problems for blockchain are waiting to be solved. In this study, we propose a novel linkable ring signature scheme with stealth addresses, which enables the payer and payee of the transaction to be anonymous and unlinkable in the cryptocurrency. The scheme is combined with an elliptic curve discrete logarithm (ECD logarithm)-based key encapsulation mechanism (KEM) stage and a lattice-based signature stage. The master public key and master secret key are much smaller compared with the previous scheme. Complete secure proof of the scheme is also presented in this study.

Linkable Ring Signature Scheme Using Biometric Cryptosystem and NIZK and Its Application

Biometric encryption, especially based on fingerprint, plays an important role in privacy protection and identity authentication. In this paper, we construct a privacy-preserving linkable ring signature scheme. In our scheme, we utilize a fuzzy symmetric encryption scheme called symmetric keyring encryption (SKE) to hide the secret key and use non-interactive zero-knowledge (NIZK) protocol to ensure that we do not leak any information about the message. Unlike the blind signature, we use NIZK protocol to cancel the interaction between the signer (the prover) and the verifier. The security proof shows that our scheme is secure under the random oracle model. Finally, we implement it on a personal computer and analyze the performance of the constructed scheme in practical terms. Based on the constructed scheme and demo, we give an anonymous cryptocurrency transaction model as well as mobile demonstration.

Identity-Based Linkable Ring Signature on NTRU Lattice

Although most existing linkable ring signature schemes on lattice can effectively resist quantum attacks, they still have the disadvantages of excessive time and storage overhead. This paper constructs an identity-based linkable ring signature (LRS) scheme over NTRU lattice by employing the technologies of trapdoor generation and rejection sampling. The security of this scheme relies on the small integer solution (SIS) problem on NTRU lattice. We prove that this scheme has unconditional anonymity, unforgeability, and linkability under the random oracle model (ROM). Through the performance analysis, this scheme has a shorter size of public/private keys, and when the number of ring members is small (such as N ≤ 8 ), this scheme has a shorter signature size compared with other existing latest lattice-based LRS schemes. The computational efficiency of signature has also been further improved since it only involves multiplication in the polynomial ring and modular operations of small integers. Finally, we implemented our scheme and other similar schemes, and it is shown that the time for the signature generation and verification of this scheme decreases roughly by 44.951% and 33.503%, respectively.

An efficient lattice-based linkable ring signature scheme with scalability to multiple layer

In this paper, we propose a novel lattice-based linkable ring signature scheme based on the Borromean ring signature. In our scheme, to avoid the extra overhead caused by reject sampling that used in the existing schemes, we use an exact indistinguishable distribution to replace it. Using our method, signature will be successfully generated without repeating, so the size of the signature can be reduced. Furthermore, our scheme can be extended to multiple layers easily. We also propose a lattice-based multilayer linkable ring signature scheme which can be use for transactions with multiple inputs. Then, we prove that our scheme has unforgeability, anonymity, linkability and non-slanderability that a linkable ring signature scheme should have. Efficiency analysis shows that our scheme has a smaller signature size under the same security conditions.

Polymerized RingCT: An Efficient Linkable Ring Signature for Ring Confidential Transactions in Blockchain

In this work, we study and refer the privacy protection protocol used in the blockchain, in particular, the Ring Confidential Transaction protocol in current popular anonymous cryptocurrency Monero. Based on our observations on the underlying linkable ring signature and homomorphic commitment schemes, we design a new efficient RingCT protocol for protecting user’s transaction information. Our scheme is built on the Schnorr ring signature, the well-known Pedersen commitment and signature of knowledge. We show that the signature algorithm used in our scheme satisfies the security requirements under random oracle model and adaptive chosen message attack. Moreover, compared with other ring confidential transactions protocols, our scheme can significantly save the cost of operation and interaction linearly under multi-account operation, that is, unlike other schemes, the cost of its underlying signature algorithm doesn't grow linearly as the spender’s accounts grow.

On Design of Single-Layer and Multilayer Code-Based Linkable Ring Signatures

In this paper, we present an effective code-based linkable ring signature scheme based on Borromean ring signature. The security of the scheme is based on the hardness of Syndrome Decoding problem, General Syndrome Decoding problem and Codeword Finding problem. We prove that our scheme has all the properties that a linkable ring signature scheme should have: unforgeability, anonymity, linkability and non-slanderability. Efficiency analysis shows that our scheme has a smaller signature size than the existing scheme under the same security conditions. Furthermore, this signature scheme can be easily extended to multiple layers. That is, code-based multilayer linkable ring signature scheme can be obtained and used for transactions with multiple inputs.

Certificateless Linkable Ring Signature Scheme

Ring signature is an anonymous signature that both authenticates the message and protects the identity information of the signer. It is suitable for scenarios such as anonymous network access, online auctions, etc. However, there is a problem in a regular ring signature scheme. The signer can generate multiple different signatures for the same message without being discovered by the verifier. This will of course cause some confusion. Linkable ring signature (LRS) resolves the problem. The verifier can determine if multiple signatures were generated by the same signer, but he cannot determine the actual signer’s identity. In this paper, we first proposed the system model and security requirements for certificateless linked ring signature (CL-LRS). Then, we constructed a concrete CL-LRS scheme and gave the security proofs. Finally, we compared the efficiency of our scheme with several other LRS schemes. Our scheme does not use pairing operation and is more suitable for the computation-constrained environment.

Identity-Based Linkable Ring Signature Scheme

A ring signature is an anonymous signature that implements both the authentication of the message and the anonymity of the signer. In a “normal” ring signature scheme, the same signer can generate multiple ring signatures, but the verifier cannot find this fact. Linkable ring signature (LRS) solves the problem. In the setting, the identity of the signer is still anonymous, and if the same signer generates multiple ring signatures, the verifier can confirm the fact. Linkable ring signatures are applied to some actual scenarios, such as e-cash, e-voting and ad-hoc network authentication. In this paper, we presented a new identity-based linkable ring signature scheme that avoids certificate management. We then gave the security proofs in the random oracle model (ROM) and compared the efficiency of it with the previous schemes. The new scheme requires only 7 pairing operations in signing and verifying. It is the most efficient linkable ring signature in the identity-based setting.

Forward-Secure Linkable Ring Signatures from Bilinear Maps

We present the first linkable ring signature scheme with both unconditional anonymity and forward-secure key update: a powerful tool which has direct applications in elegantly addressing a number of simultaneous constraints in remote electronic voting. We propose a comprehensive security model, and construct a scheme based on the hardness of finding discrete logarithms, and (for forward security) inverting bilinear or multilinear maps of moderate degree to match the time granularity of forward security. We prove efficient security reductions—which, of independent interest, apply to, and are much tighter than, linkable ring signatures without forward security, thereby vastly improving the provable security of these legacy schemes. If efficient multilinear maps should ever admit a secure realisation, our contribution would elegantly address a number of problems heretofore unsolved in the important application of (multi-election) practical Internet voting. Even if multilinear maps are never obtained, our minimal two-epoch construction instantiated from bilinear maps can be combinatorially boosted to synthesise a polynomial time granularity, which would be sufficient for Internet voting and more.

Linkable Ring Signature with Unconditional Anonymity

In this paper, we construct a linkable ring signature scheme with unconditional anonymity. It has been regarded as an open problem in [22] since 2004 for the construction of an unconditional anonymous linkable ring signature scheme. We are the first to solve this open problem by giving a concrete instantiation, which is proven secure in the random oracle model. Our construction is even more efficient than other schemes that can only provide computational anonymity. Simultaneously, our scheme can act as an counterexample to show that [19, Theorem 1] is not always true, which stated that linkable ring signature scheme cannot provide strong anonymity. Yet we prove that our scheme can achieve strong anonymity (under one of the interpretations).