In cryptography, a ring signature is anonymous as it hides the signer’s identity among other users. When generating the signature, the users are arranged as a ring. Compared with group signatures, a ring signature scheme needs no group manager or special setup and supports flexibility of group choice. However, the anonymity provided by ring signatures can be used to conceal a malicious signer and put other ring members under suspicion. At the other extreme, it does not allow the actual signer to prove their identity and gain recognition for their actions. A deniable ring signature is designed to overcome these disadvantages. It can initially protect the signer, but if necessary, it enables other ring members to deny their involvement, and allows the real signer to prove who made the signed action. Many real-world applications can benefit from such signatures. Inspired by the requirement for them to remain viable in the post-quantum age, this work proposes a new non-interactive deniable ring signature scheme based on lattice assumptions. Our scheme is proved to be anonymous, traceable and non-frameable under quantum attacks.
In cryptography, a ring signature is anonymous as it hides the signer’s identity among other users. When generating the signature, the users are arranged as a ring. Compared with group signatures, a ring signature scheme needs no group manager or special setup and supports flexibility of group choice. However, the anonymity provided by ring signatures can be used to conceal a malicious signer and put other ring members under suspicion. At the other extreme, it does not allow the actual signer to prove their identity and gain recognition for their actions. A deniable ring signature is designed to overcome these disadvantages. It can initially protect the signer, but if necessary, it enables other ring members to deny their involvement, and allows the real signer to prove who made the signed action. Many real-world applications can benefit from such signatures. Inspired by the requirement for them to remain viable in the post-quantum age, this work proposes a new non-interactive deniable ring signature scheme based on lattice assumptions. Our scheme is proved to be anonymous, traceable and non-frameable under quantum attacks.
A ring signature (RS) scheme enables a group member to sign messages on behalf of its group without revealing the definite signer identify, but this also leads to the abuse of anonymity by malicious signers, which can be prevented by traceable ring signatures (TRS). Up until that point, traceable ring signatures have been secure based on the difficult problem of number-theoretic (discrete logarithms or RSA), but since the advent of quantum computers, traditional traceable ring signatures may no longer be secure. Thus Feng proposed a lattice based TRS, which are resistant to attacks by quantum computers. However, that works did not tackle the certificate management problem. To close this gap, a quantum-resistant certificateless TRS scheme was proposed in the study. To the best of our knowledge, this is the first lattice based certificateless TRS. In detail, a specific TRS scheme was combined with the lattice-based certificateless signature technology to solve the certificate management problem while avoid key escrow problem. Additionally, a better zero-knowledge protocol is used to improve the computational efficiency of the scheme, and by reducing the soundness error of the zero-knowledge protocol, the number of runs of the zero-knowledge protocol is reduced, so that the communication overhead of the scheme is reduced. Under random oracle model, the proposed scheme satisfies tag-linkability, anonymity, exculpability and is secure based on the SIS problem and the DLWE problem. In conclusion, the proposed scheme is more practical and promising in e-voting.
Ring signatures, a novel cryptographic primitive, were introduced by Rivest, Shamir, and Tauman at ASIACRYPT 2001. It allows a member of a group to sign a message on behalf of an ad-hoc group of users, known as a ring, without revealing its identity. Ring signatures, initially introduced for applications such as whistle-blowing and confidential disclosures, have since gained significant relevance and widespread adoption across various domains, including blockchain technologies, ad-hoc networks, anonymous transactions, location-based services, cloud computing platforms, and outsourced computation. However, traditional ring signatures are vulnerable if the signers’ keys are compromised. To resolve this vulnerability, Liu and Wong introduced the notion of forward-secure ring signatures at IJNS 2008. Forward-security ensures that even if a signer’s secret key is compromised, signatures generated in prior time periods remain secure. It significantly reduces the damage caused by secret key exposure, making it crucial for long-term security in applications such as whistle-blowing or anonymous authentication. However, most existing forward-secure ring signature schemes are based on number-theoretic assumptions, making them vulnerable to quantum adversaries. Yu and Wang proposed a quantum-safe forward-secure ring signature scheme at ICICS 2023, and Yu et al. further extended this work in Computer Networks (2025), retaining the same ring signature scheme with forward security. But the scheme suffers from large signatures that grow linearly with the ring size. In this paper, we propose a lattice-based forward-secure ring signature scheme in the quantum random oracle model ( QROM ) that simultaneously achieves security against quantum adversaries and compact signature size. Notably, the signature size is logarithmic in the number of members in the ring, enabling significantly better scalability compared to prior constructions.
Among post-quantum alternatives, latticebased cryptography is the most promising one, due to its simple operations, reduction from aver-age-case to worstcase hardness, and supporting of rich functionalities. Ring signature enables a user to sign anonymously on behalf of an adaptively chosen group, and has multiple applications in anonymous e-voting, anonymous authentication, whistle blowing etc. However, most lattice-based ring signature schemes were constructed in the random oracle model from lattice basis delegation and they suffer large verification key sizes as a common disadvantage. This work proposes an efficient ring signature scheme from lattice basis delegation without random oracle based on the extended split-SIS problem, whose security is approximately as hard as the worst-case SIVP problem. Our scheme is proved to be anonymous and existentially unforgeable under latticebased assumptions. Finally, the verification key size is significantly reduced to a small constant, instead of increasing linearly with the number of ring members.
In quantum cryptography research area, quantum digital signature is an important research field. To provide a better privacy for users in constructing quantum digital signature, the stronger anonymity of quantum digital signatures is required. Quantum ring signature scheme focuses on anonymity in certain scenarios. Using quantum ring signature scheme, the quantum message signer hides his identity into a group. At the same time, there is no need for any centralized organization when the user uses the quantum ring signature scheme. The group used to hide the signer identity can be immediately selected by the signer himself, and no collaboration between users.Since the quantum finite automaton signature scheme is very efficient quantum digital signature scheme, based on it, we propose a new quantum ring signature scheme. We also showed that the new scheme we proposed is of feasibility, correctness, anonymity, and unforgeability. And furthermore, the new scheme can be implemented only by logical operations, so it is easy to implement.
Anonymous authentication schemes such as group signatures and anonymous credentials are important privacy-protecting tools in electronic communications. The only currently known scheme based on assumptions that resist quantum attacks is the group signature scheme by Gordon et al. (ASIACRYPT 2010). We present a generalization of group signatures called anonymous attribute tokens where users are issued attribute-containing credentials that they can use to anonymously sign messages and generate tokens revealing only a subset of their attributes. We present two lattice-based constructions of this new primitive, one with and one without opening capabilities for the group manager. The latter construction directly yields as a special case the first lattice-based group signature scheme offering full anonymity (in the random-oracle model), as opposed to the practically less relevant notion of chosen-plaintext anonymity offered by the scheme of Gordon et al. We also extend our scheme to protect users from framing attacks by the group manager, where the latter creates tokens or signatures in the name of honest users. Our constructions involve new lattice-based tools for aggregating signatures and verifiable CCA2-secure encryption.
Anonymous credential schemes are a key application in modern cryptography. Recent research has advanced these schemes by incorporating issuer-hiding capabilities, which prevent the disclosure of the credential issuer’s identity. While several issuer-hiding anonymous credential schemes exist, none offer resilience against quantum computing adversaries. To address this gap, we propose a post-quantum issuer-hiding anonymous credential scheme, building on the recent work known as ring referral (S&P ’25), which allows anonymous signatures from third-party signers. Ring referral is an integration of ring signature and anonymous credential schemes, enabling issuer-hiding anonymous credentials. In this paper, we present an efficient lattice-based ring referral scheme, which supports quantum-resistant security. Our scheme extends a recent lattice-based credential scheme (CCS ’24) via LNP proof system (CRYPTO ’22).