Anonymous veto networks (AV-nets), originally proposed by Hao and Zielinski (2006), are particularly lightweight protocols for evaluating a veto function in a peer-to-peer network such that anonymity of all protocol participants is preserved.Prior to this work, anonymity in all AV-nets from the literature relied on the decisional Diffie-Hellman (DDH) assumption and can thus be broken by (scalable) quantum computers.In order to defend against this threat, we propose two practical and completely lattice-based AV-nets.The first one is secure against passive and the second one is secure against active adversaries.We prove that anonymity of our AV-nets reduces to the ring learning with errors (RLWE) assumption.As such, our AV-nets are the first ones with post-quantum anonymity.We also provide performance benchmarks to demonstrate their practicality.
Anonymous veto networks (AV-nets), originally proposed by Hao and Zielinski (2006), are particularly lightweight protocols for evaluating a veto function in a peer-to-peer network such that anonymity of all protocol participants is preserved.Prior to this work, anonymity in all AV-nets from the literature relied on the decisional Diffie-Hellman (DDH) assumption and can thus be broken by (scalable) quantum computers.In order to defend against this threat, we propose two practical and completely lattice-based AV-nets.The first one is secure against passive and the second one is secure against active adversaries.We prove that anonymity of our AV-nets reduces to the ring learning with errors (RLWE) assumption.As such, our AV-nets are the first ones with post-quantum anonymity.We also provide performance benchmarks to demonstrate their practicality.
Quantum Anonymous Veto (QAV) protocols enable secure and anonymous decision-making by allowing participants to detect the presence of a veto without revealing individual choices. While existing QAV schemes offer strong theoretical guarantees, they face significant limitations in practical implementation due to resource requirements, scalability issues, and the need for multipartite entanglement. In this work, we propose a novel deterministic QAV protocol that leverages only bipartite entanglement in the form of Bell states and achieves conclusive veto detection in a single round. Our approach eliminates the need for multi-qubit entangled states and iterative rounds, thereby significantly reducing experimental overhead and enhancing scalability. The protocol preserves critical properties such as voter anonymity, correctness, and verifiability, making it well-suited for implementation on near-term quantum devices. Furthermore, we outline a practical photonic realization based on polarization-path encoding and discrete-time quantum walks, demonstrating its feasibility within current quantum optical platforms. This work contributes a resource-efficient and experimentally viable alternative to existing QAV schemes, advancing the prospects of secure quantum decision-making in distributed systems.
The onion routing (OR) network Tor provides anonymity to its users by routing their encrypted traf-fic through three proxies (or nodes). The key cryptographic challenge, here, is to establish symmetric session keys using a secure key exchange between the anonymous users and the selected nodes. The Tor network currently employs a one-way authenticated key exchange (1W-AKE) protocol ntor for this purpose. Nevertheless, ntor as well as other known 1W-AKE protocols rely solely on some classical Diffie-Hellman (DH) type assumptions for their (forward) security, and thus privacy of today’s anony-mous communication cannot be ensured once quantum computers arrive. In this paper, we demonstrate utility of quantum-secure lattice-based cryptography towards solving this problem for onion routing. In particular, we present a novel hybrid 1W-AKE protocol (HybridOR) that is secure under the lattice-based ring learning with error (ring-LWE) assumption as well as the gap DH assumption. Due to its hybrid design, HybridOR is not only resilient against quantum attacks but also allows the OR nodes to use the current DH public keys and subsequently requires no modification to the current Tor public key infrastructure. Moreover, thanks to the recent progress in lattice-based cryp-tography in the form of efficient ring-based constructions, our protocol is also computationally more efficient than the currently employed 1W-AKE protocol ntor, and it only introduces small and manage-able communication overhead to the Tor protocol.
Objective: To design a secure and efficient three-party post-quantum authenticated key agreement (AKE) protocol that ensures mutual authentication, user anonymity, and forward secrecy, while resisting both classical and quantum adversaries. Methods: The proposed protocol is constructed using the Ring Learning with Errors (Ring-LWE) assumption, which is widely regarded as quantum-resistant. The scheme enables two users to establish a shared session key through a trusted server over an insecure channel. Cryptographic hash functions, lattice-based operations, and masking techniques are employed to achieve authentication, anonymity, and key confidentiality. Formal correctness proofs, informal security analysis, and comparative performance evaluations are conducted to validate the protocol. Findings: The study describes qualitative benefits like "outperforms current protocols" but lacks specific metrics, such as exact computation costs (e.g., 4913 ns total execution) or communication rounds, and "reduces user-side cost to 2438 ns vs. 5395 ns in Islam et al.". Also, substantially more efficient than pairing- or chaotic-map-based protocols, which incur costs exceeding 12000 ns. Communication overhead is reduced by limiting the exchange to two RLWE-based messages and one server response, avoiding expensive bilinear pairing or biometric hash transmissions. These results demonstrate that the proposed scheme provides stronger security guarantees at a lower computational and communication cost, making it suitable for resource-constrained mobile and IoT environments. Novelty: Unlike existing approaches, the proposed protocol simultaneously guarantees user anonymity, forward secrecy, and quantum resistance in a three-party setting based on Ring-LWE. It overcomes known vulnerabilities in prior schemes and achieves improved efficiency without compromising security, making it a practical and robust solution for post-quantum secure communications. Keywords: Key Establishment, Authentication, Ring Learning with Errors, Anonymous Key Exchange, Post Quantum Forward Secrecy
Anonymous Veto (AV) and Dining cryptographers (DC) are two basic primitives for the cryptographic problems where the main aim is to hide the identity of the senders of the messages. These can be achieved by classical methods where the security is based either on computational hardness or on shared private keys. In this regard, we present a secure quantum protocol for both DC and AV by exploiting the GHZ correlations. We first solve a generalized version of the DC problem with the help of multiparty GHZ state. This allow us to provide a secure quantum protocol for the AV. Securities for both the protocols rely on some novel and fundamental features of GHZ correlations related to quantum nonlocality.
Authentication on the Internet usually has the drawback of leaking the identity of the users, or at least allowing to trace them from a server to another. Anonymous credentials overcome this issue, by allowing users to reveal the attributes necessary for the authentication, without revealing any other information (in particular not their identity). In this article, we provide a generic framework to construct anonymous credential schemes and use it to give a concrete construction of post-quantum (lattice-based) anonymous credential protocol. Our protocol thus allows for long-term security even when one considers the emergence of quantum computers able to break widely used traditional computational assumptions, such as RSA, the discrete logarithm or Diffie-Hellman. We also give a concrete implementation of our protocol, which is only one order of magnitude slower and bandwidth consuming than previous anonymous credentials that are not post-quantum.
Full-duplex communication is a transformative technology in next-generation networks, enabling simultaneous transmission and reception for both high efficiency and low latency. In this paper, we integratefull duplexitywith QAC, developing a quantum dimension of full-duplex anonymity to address the stringent demands for communication efficiency, security, and privacy in emerging networks. Specifically, we design two full-duplex (FD-QAC) protocols for the bidirectional, secure, and anonymous exchange of classical information with the help of a server. The first FD-QAC protocol, tailored for ring-type quantum networks, ensures that even an adversary with full network access cannot determine communicating identities—achievingperfect untraceability. The second FD-QAC protocol, designed for star-type quantum networks, improves scalability, security, and resilience against dishonest participant attacks. We provide the anonymity analysis demonstrating the robustness of these QAC protocols against external adversaries and malicious participants in adversarial quantum networks. Furthermore, we evaluate the error performance of the protocols in noisy quantum networks, illustrating that this quantum full-duplex anonymity is both reliable and scalable.