In user–server authentication environments, persistent server-side verification tables, such as password verifiers, shared authentication records, or per-user secret tables, may become a critical point of failure once leaked. To address this problem in the post-quantum setting, this paper proposes an ML-DSA-specific verification-table-free authenticated key agreement (AKA) scheme based on the NIST-standardized Module-Lattice-Based Digital Signature Algorithm (ML-DSA). The main contribution is a protocol-level use of the signer-recoverable masking vector in ML-DSA as an on-demand reconstruction mechanism for user-related authentication material. This enables the server to reconstruct the required user-related authentication material from its own signature and long-term secret key. This architecture reduces the exposure associated with centralized verification-table leakage, but it should be understood as a storage-relocation tradeoff rather than a storage-free design, because each user must retain the issued signature and the corresponding hash-derived authentication value. By combining the recovered value with identity information through a quantum-resistant one-way hash function, the server can authenticate the user and establish a session key. Its security is analyzed within a Canetti–Krawczyk-style adversarial model and further discussed in the random-oracle setting through a sequence-of-games argument. The analysis supports session-key indistinguishability under the stated freshness and exposure assumptions, while explicitly excluding full forward secrecy under compromise of the server’s long-term ML-DSA secret key. In addition, an operation-level comparison is provided to clarify computational, storage, and communication tradeoffs relative to representative post-quantum AKA schemes. Since the present work does not include implementation-level benchmarking, the performance discussion should be interpreted as analytical rather than empirical validation. The proposed scheme is therefore most suitable for account-login-oriented applications in which reducing centralized verification-table leakage is a primary design objective and where user-side credential storage can be securely managed.
In user–server authentication environments, persistent server-side verification tables, such as password verifiers, shared authentication records, or per-user secret tables, may become a critical point of failure once leaked. To address this problem in the post-quantum setting, this paper proposes an ML-DSA-specific verification-table-free authenticated key agreement (AKA) scheme based on the NIST-standardized Module-Lattice-Based Digital Signature Algorithm (ML-DSA). The main contribution is a protocol-level use of the signer-recoverable masking vector in ML-DSA as an on-demand reconstruction mechanism for user-related authentication material. This enables the server to reconstruct the required user-related authentication material from its own signature and long-term secret key. This architecture reduces the exposure associated with centralized verification-table leakage, but it should be understood as a storage-relocation tradeoff rather than a storage-free design, because each user must retain the issued signature and the corresponding hash-derived authentication value. By combining the recovered value with identity information through a quantum-resistant one-way hash function, the server can authenticate the user and establish a session key. Its security is analyzed within a Canetti–Krawczyk-style adversarial model and further discussed in the random-oracle setting through a sequence-of-games argument. The analysis supports session-key indistinguishability under the stated freshness and exposure assumptions, while explicitly excluding full forward secrecy under compromise of the server’s long-term ML-DSA secret key. In addition, an operation-level comparison is provided to clarify computational, storage, and communication tradeoffs relative to representative post-quantum AKA schemes. Since the present work does not include implementation-level benchmarking, the performance discussion should be interpreted as analytical rather than empirical validation. The proposed scheme is therefore most suitable for account-login-oriented applications in which reducing centralized verification-table leakage is a primary design objective and where user-side credential storage can be securely managed.
Modern instant messaging systems require end-to-end (E2E) security guarantees while operating over server-mediated infrastructures that cannot be fully trusted. At the same time, the impending transition to post-quantum cryptography raises nontrivial challenges for the design of secure messaging protocols that preserve these guarantees. In this work, we present the design of a post-quantum end-to-end secure protocol for instant messaging applications under an untrusted relay model. The proposed construction relies on lattice-based primitives standardized by NIST, namely ML-KEM for key establishment and ML-DSA for authentication, and follows a Double-KEM pattern combined with explicit context binding to derive an E2E session key known only to the communicating clients. The server acts solely as an authenticated relay and never gains access to plaintext messages or session keys. In addition to the protocol design, we complement the protocol description with an automated symbolic verification using ProVerif, establishing injective mutual authentication and session-key secrecy under a Dolev–Yao adversary model. Finally, we characterize the computational cost of different authentication and verification policies and evaluate the performance of the handshake on heterogeneous cloud-based architectures. The results provide practical insight into the feasibility of deploying post-quantum end-to-end secure protocols within existing instant messaging infrastructures.
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
Introduction Session establishment, the process by which two parties authenticate each other and derive a shared secret key, forms the foundation for secure digital communication. Quantum computers threaten this foundation by breaking classical public-key primitives such as RSA and elliptic-curve Diffie–Hellman (ECDH), thereby enabling harvest-now–decrypt-later (HNDL) attacks that endanger long-term confidentiality. Methods This paper presents the design, implementation, and evaluation of an authenticated, quantum-resistant session protocol that replaces these vulnerable mechanisms with their post-quantum counterparts. The proposed protocol integrates ML-KEM-1024 (FIPS 203; CRYSTALS, Kyber) for ephemeral key exchange, ML-DSA-65 (FIPS 204; CRYSTALS, Dilithium) for endpoint authentication, and AES-256-GCM for symmetric protection. A transcript-bound HKDF–SHA3-256 key schedule and a 96-bit GCM nonce construction with conservative rekey limits are used to ensure forward secrecy, downgrade resistance, and message integrity. A Python/C prototype (PQClean ML-KEM-1024 with PyCryptodome AES-256-GCM) was benchmarked over 1,000 iterations on commodity hardware. Results The results show that sub-millisecond cryptographic overhead ML-KEM-1024 matches the performance of X25519 while vastly outperforming RSA-3072 in secure session establishment, and symmetric encryption remains cost effective. Nonces are unique 96-bit values, never reused across directions or beyond 2³² records, following NIST SP 800-38D; when nonce-misuse resistance is required, AES-256-GCM-SIV (RFC 8452) is supported as a drop-in alternative. Empirical tests under both local and WAN-emulated ( ≈ 40 ms RTT) network conditions confirm that the additional post-quantum cost maintains the handshake cryptographic latency in the 0.50–0.70 ms range. Discussion These results demonstrate that fully authenticated, forward-secure, quantum-resistant session negotiation is practical for real-world deployments.
Abstract The authenticated key agreement (AKA) method used in the Internet of Things (IoT) provides identity authentication and agreed symmetric keys to encrypt large amounts of communication messages for devices and servers. With the development of the quantum computing techniques and corresponding algroithms, classical authenticated key agreement methods based on public key, such as RSA and ECC become vulnerable. Many scholars have proposed lattice-based authenticated key agreement schemes to achieve post-quantum security and address this issue. However, these scheme's security models (such as BR, CK, and ROR) only can capture limited types of adversary attacks and require many communication rounds. To this end, we propose a lower communication rounds lattice-based anonymous authenticated key agreement (LA-AKA) protocol under the seCK model, which can capture a wider range of adversary attacks. The LA-AKA scheme utilizes an identity-based public key system for key agreement, and this system avoids complex resource consumption caused by certificate verification. During the identity authentication and key agreement phase, the communication entities do not need to transmit static public keys; they only need to engage in two communication rounds to generate the session key. Furthermore, the LA-AKA scheme can resist signal leakage attacks caused by key reuse in the ring learning with errors (RLWE) security assumption. The LA-AKA scheme provides higher security, as security analysis proves. The performance evaluation shows that as the number of devices and servers in the system increases, the computational advantage of the LA-AKA scheme in the broadcast channel becomes more significant.
The transition to post-quantum cryptography is reshaping the Secure Shell (SSH) protocol for remote administration. Post-quantum key exchange has been deployed in OpenSSH and is being standardized, while SSH authentication largely remains a signature-replacement effort. This path preserves the familiar public-key credential model, but inherits the size and computation overhead of post-quantum signatures, which can increase latency, traffic, and server-side load. KEM-based authentication offers a natural alternative to this signature-centric path, and SSH makes this especially attractive at the user-authentication layer, which is method-extensible, separated from transport-layer key exchange and host-key authentication, and already protected by the established channel. We present a drop-in KEM-based user-authentication method for SSH that replaces client public-key signatures with a session-bound challenge-response proof. The method fits into SSH's existing user-authentication framework, preserving the public-key credential model and enabling incremental deployment alongside existing methods. We provide a reduction-based security argument in the post-quantum ACCE framework, implement the design in OpenSSH using liboqs, and evaluate it under representative RTTs, TCP initial-window settings, and post-quantum migration configurations. Our results show that KEM-based authentication is competitive with compact signature-based authentication under representative network settings, while reducing median handshake latency by up to about 10% against large-signature hybrid baselines. The advantages are clearer when post-quantum signatures stress transmission or computation: median latency under small TCP initial windows falls by up to 7.3% versus ML-DSA and 17.9% versus SLH-DSA, while server-side online cryptographic cost is 59.1% lower than that for ML-DSA in the same NIST category.
To meet the requirement of doctors’ comprehensive diagnosis and treatment across multiple servers in smart healthcare, and to address the lack of efficient switching mechanisms in existing post-quantum authentication schemes, a post-quantum password authentication and fast-switching key agreement protocol for multi-server smart healthcare environments was proposed. With ML-KEM as the core cryptographic primitive, a mechanism combining initial authentication and fast switching authentication was designed. In the initial authentication phase, full authentication was performed, and a master session key and a service session key were established. During multi-server access, fast switching authentication was performed, and a new service session key was independently negotiated with the target server. In terms of security, the session key semantic security of the proposed protocol was proved under the ROR model, and resistance to common attacks was analyzed. In terms of performance, when a user continuously accessed five servers, compared with the repeated full-authentication approach in Wen’s and Chen’s post-quantum schemes, the proposed protocol reduced the cumulative computational overhead by more than 70.34% and the cumulative communication overhead by more than 27.53%. The performance gap increases as the number of servers grows, which shows that the proposed protocol has significant efficiency advantages and good scalability in large-scale deployment scenarios.