Quantum-Resistant Authentication Protocol

Updated 2 December 2025

Quantum-resistant authentication protocols are mechanisms that leverage post-quantum cryptography and quantum communication to secure authentication even against large-scale quantum attacks.
They minimize reliance on pre-shared secrets by employing quantum-safe public-key infrastructures and innovative integration with quantum key distribution for forward secrecy.
These protocols achieve rapid, sub-millisecond handshakes and robust protection against replay, impersonation, and man-in-the-middle attacks through advanced design and efficient key management.

A quantum-resistant authentication protocol is an authentication mechanism designed to remain secure even if adversaries possess large-scale quantum computational resources. Such protocols must neutralize quantum attacks, notably those exploiting Shor’s or Grover’s algorithms, and achieve authentication guarantees over insecure networks against quantum polynomial-time (QPT) adversaries. The field encompasses both cryptographically rigorous classical protocols—mainly based on post-quantum cryptography (PQC), e.g., lattice-based digital signatures and key encapsulation mechanisms—and protocols leveraging quantum communication or entanglement. A recurring theme is the synergy between quantum key distribution (QKD), which provides information-theoretic key secrecy, and PQC primitives used for classical channel authentication. A notable structural innovation is the minimization of pre-shared secrets, either by using quantum-safe public-key infrastructures (PKI) or quantum hardware-based authentication. The protocols underpinning quantum-resistant authentication operate under short-term security assumptions for the authenticating primitive, ultimately achieving long-term quantum-resistant confidentiality and integrity for distributed keys and payloads (Wang et al., 2022).

1. Core Principles and Security Models

Quantum-resistant authentication protocols must achieve message integrity, authenticity, unforgeability, and resistance to replay, impersonation, reflection, man-in-the-middle (MitM), and offline guessing attacks, even under the assumption that adversaries wield quantum computation (Wang et al., 2022, Liu-Jun et al., 2020, Kumar et al., 25 Nov 2025). Security reductions base unforgeability on the hardness of quantum-resistant problems such as Learning With Errors (LWE), Short Integer Solution (SIS), or QMA-complete problems (e.g., Quantum Marginal Consistency), and/or rely on inherent quantum physical properties—no-cloning, measurement disturbance, and entanglement monogamy (Liu et al., 20 Jun 2025, Goswami et al., 15 Apr 2025). Authentication is formalized using simulation-based, real/ideal security paradigms, quantifying adversary advantage via existential unforgeability under chosen-message or chosen-plaintext attacks (EUF-CMA/EUF-qCMA, CPA). Tag generation leverages either information-theoretic universal hashing (Wegman–Carter MAC), PQC digital signatures (e.g., Dilithium, Aigis-Sig, ML-DSA), quantum state encodings (BB84-style), or quantum pseudorandom unitaries (Garg et al., 2016, Haug et al., 1 Jan 2025).

2. PQC-Based Authentication Mechanisms

The vast majority of practical quantum-resistant authentication protocols are built on lattice-based signature and KEM schemes standardized by NIST (e.g., Dilithium, Kyber) and module-lattice constructions (ML-DSA, ML-KEM). Their principal advantage is non-reliance on pre-shared symmetric keys, eliminating the $O(n^2)$ key provisioning overhead in large QKD networks. Instead, a single $O(n)$ certificate per user suffices with PKI (Wang et al., 2022, Liu-Jun et al., 2020). PQC signatures satisfy unforgeability against quantum attacks by relying on the computational hardness of LWE, SIS, or structured module/SIS problems. Protocols instantiate authentication tags via direct signing of cryptographic digests (e.g., $Tag = \mathrm{Sign}_{S}(H(\mathrm{MSG}))$ ) and certificate verification. PQC KEMs are used for secure key distribution or message encapsulation, with forward secrecy and resistance to replay attacks ensured by ephemeral key mixes and privacy amplification. Protocols generally assume PQC only needs to be unbroken for a short window (e.g., $T \approx 1$ s, the duration of each QKD round), since leakage is eliminated in subsequent privacy amplification (Wang et al., 2022).

3. Quantum-Authenticated Protocols and Hybrid Schemes

Quantum communication can enhance classical authentication or act as a primitive for authentication. BB84-style quantum channels can encode authentication tags, providing partial or full information-theoretic secrecy of keys and/or tags (0806.1231). More advanced constructions leverage entanglement, local indistinguishability, and physical unclonable functions (PUFs). Offline protocols require pre-shared Bell pairs and weak PUFs; authentication is achieved by matching classical outcomes of basis measurements on shared entangled states, and security relies on local indistinguishability and monogamy of entanglement (exponential soundness: attack success probability $2^{-m}$ per round for $m$ -bit PUF outputs) (Goswami et al., 15 Apr 2025). Online protocols (using HEPUF modules) replace Bell pair pre-distribution with quantum state generation at the prover, operating with minimal classical communication and quantum resource overhead. All these quantum-enhanced mechanisms fundamentally resist quantum attacks by leveraging physical principles, not merely computational hardness.

Hybrid classical/quantum approaches (defense-in-depth) combine QKD for post-compromise key confidentiality and PQC signatures (e.g., Dilithium) for entity authentication at initial setup or per message, ensuring resilience even against future breakthroughs in lattice cryptanalysis (Prisco, 2023, Wang, 5 Mar 2025).

4. Replay, Impersonation, and Forward Secrecy

Replay resistance in quantum-resistant authentication is achieved via fresh nonces, challenge–response flows, ephemeral key exchange, and privacy amplification. Lattice-based signatures and ephemeral key encapsulation tightly bind each authentication session to one-time-use randomness so that replayed digests or tags fail subsequent key or message verification with overwhelming probability ( $2^{-k}$ for $k$ -bit key material) (Wang et al., 2022). Compromising long-term keys post-authentication, or breaking PQC algorithms years later, does not retroactively compromise QKD-derived keys or session tokens; privacy amplification or ephemeral encapsulation ensures perfect forward secrecy (Wang et al., 2022, Riva-Cambrin et al., 22 May 2025, Ko et al., 5 Feb 2025).

Protocols such as those for RFID mutual authentication use fresh ISIS commitments, one-way hash checks, and ephemeral randomness per run, attaining replay-immunity and unforgeability even on dual-insecure channels (Kumar et al., 25 Nov 2025).

5. Key Management, Scalability, and PKI

Classical pre-shared symmetric schemes scale poorly, requiring manual distribution of $O(n^2)$ keys for $n$ -user QKD networks and imposing high logistics and trust burdens (face-to-face, trusted relay topologies) (Wang et al., 2022, Liu-Jun et al., 2020). Quantum-resistant authentication based on PQC and PKI achieves $O(n)$ storage and on-demand extensibility: new users simply obtain a digital certificate from the CA, instantly joining the network without further secret-sharing. PKI-based PQC signatures (Aigis-Sig, Dilithium) are compatible with X.509-style certificates; a single CA becomes the only trusted anchor. In lattice-based token protocols, device public keys and permissions are embedded in lightweight transparent tokens or certificates, and minimal server-side state is needed (e.g., hash of token and preview proposal) (Riva-Cambrin et al., 22 May 2025).

Entanglement-enabled authentication with PUFs requires storage and distribution of Bell pair banks and classical CRP tables, but exploits the inherent scalability of entanglement distribution platforms (e.g., photonics-on-chip) (Goswami et al., 15 Apr 2025).

6. Performance and Implementation Considerations

Quantum-resistant authentication protocols vary in resource demands:

PQC signature schemes: 2–3 kB signature size, 1 ms signing/verification time per message on commodity CPUs (Wang et al., 2022, Riva-Cambrin et al., 22 May 2025).
PQC KEM encapsulation/decapsulation: 1–1.5 ms per operation, ciphertexts of 1–2 kB, compatible with constrained IoT devices (Riva-Cambrin et al., 22 May 2025, Ko et al., 5 Feb 2025).
Tokenized protocols deliver 74 B session tokens; only the initial authentication or re-authentication incurs PQC cost, subsequent payloads use symmetric MAC/encryption (Riva-Cambrin et al., 22 May 2025).
Quantum-enhanced (BB84) authentication incurs $k$ single-qubit measurements and transmission for a $k$ -bit tag, negligible for most practical $k$ (0806.1231).
Entanglement-enabled protocols require sources capable of producing $m$ Bell pairs per round, electro-optic modulators, and limited quantum buffering (offline schemes avoid active quantum channel use during authentication) (Goswami et al., 15 Apr 2025).
Ironwood MKAAP achieves shared secrets in 30–200 ms on IoT-class MCUs and outperforms ECC key agreement for equivalent parameter settings (Anshel et al., 2017).

Parameter settings for 128–256-bit quantum security and recommended primitives (Dilithium2, Kyber512, SHA-256) are documented for various platforms (Wang et al., 2022, Riva-Cambrin et al., 22 May 2025, Kumar et al., 25 Nov 2025). Latency is generally sub-millisecond for full handshakes, meeting wireless tactile Internet requirements (URLLC) (Ahmed et al., 5 Nov 2025). Communication overhead remains sub-kilobyte per session in most designs.

7. Research Directions, Limitations, and Open Questions

Current quantum-resistant authentication is shaped by the following fundamental challenges and open research directions:

Integration of PQC key management with QKD stacks, requiring robust firmware upgradeability for evolving PQC algorithm standards (Wang et al., 2022).
Trade-offs in quantum hardware deployment, especially for quantum-enhanced protocols (cost, entanglement distribution, photonics integration) (Goswami et al., 15 Apr 2025, Ahmed et al., 5 Nov 2025).
Key recycling, composability, and leakage minimization: proof frameworks confirm total key-independence for accepted quantum authentication runs, supporting unlimited key re-use when acceptance is conditioned (Garg et al., 2016).
Extension to multi-party or identity-based settings, composable frameworks for key and tag generation, and adaptive security proofs (Haug et al., 1 Jan 2025).
Standardization and interoperability challenges across vendors, with calls for NIST/NSA-led working groups to formalize QKD and PQC authentication (Prisco, 2023).
Comparative security evaluation against quantum adversaries in constrained applications (RFID, vehicular networks, cloud services) (Kumar et al., 25 Nov 2025, Ahmed et al., 5 Nov 2025, Riva-Cambrin et al., 22 May 2025).

The field constantly evolves with new quantum hardness assumptions (e.g., QMA-complete, PRU-based, physically unclonable), expanding beyond lattice cryptography and universal hashing toward quantum-native primitives with direct hardware or tomography-based verification (Liu et al., 20 Jun 2025, Haug et al., 1 Jan 2025). The design principle remains: combine quantum information-theoretic security with robust, scalable, and extensible authentication via PQC or quantum/physical primitives to outlast both known and anticipated quantum attacks.