ABSTRACT Quantum identity authentication (QIA) can provide quantum‐interface evidence for quantum secure communication, but its interaction with public transcript handling remains insufficiently characterized. This work analyzes a raw‐feedback QIA interface based on BB84 states and operating over an authenticated classical channel, where transcript integrity is protected but receiver feedback is public. First, we establish a no‐feedback benchmark: direct impersonation reduces to binary discrimination of value‐conditioned BB84 mixed states, for which unambiguous state discrimination is impossible and maximum‐confidence discrimination gives no forced‐response advantage over minimum‐error discrimination. Second, we identify a transcript‐conditioned leakage mechanism: when an adversary retains a quantum auxiliary system, public raw feedback can condition that system into a pure‐state discrimination instance for basis‐selection information. We quantify this leakage using guessing probability, conditional min‐entropy, accessible information, and an information‐disturbance tradeoff. Third, we separate leakage from exploitation: the leakage becomes an impersonation advantage only under implementation deviations such as key‐block reuse, weak session binding, abort‐handling failure, or overly permissive thresholds. These results yield conservative authentication‐length and threshold conditions for noisy and lossy optical implementations.
ABSTRACT Quantum identity authentication (QIA) can provide quantum‐interface evidence for quantum secure communication, but its interaction with public transcript handling remains insufficiently characterized. This work analyzes a raw‐feedback QIA interface based on BB84 states and operating over an authenticated classical channel, where transcript integrity is protected but receiver feedback is public. First, we establish a no‐feedback benchmark: direct impersonation reduces to binary discrimination of value‐conditioned BB84 mixed states, for which unambiguous state discrimination is impossible and maximum‐confidence discrimination gives no forced‐response advantage over minimum‐error discrimination. Second, we identify a transcript‐conditioned leakage mechanism: when an adversary retains a quantum auxiliary system, public raw feedback can condition that system into a pure‐state discrimination instance for basis‐selection information. We quantify this leakage using guessing probability, conditional min‐entropy, accessible information, and an information‐disturbance tradeoff. Third, we separate leakage from exploitation: the leakage becomes an impersonation advantage only under implementation deviations such as key‐block reuse, weak session binding, abort‐handling failure, or overly permissive thresholds. These results yield conservative authentication‐length and threshold conditions for noisy and lossy optical implementations.
Authentication in quantum-aware communication settings requires mechanisms that verify user legitimacy while also assessing whether the communication channel exhibits excessive disturbance. This paper presents QIAP, a stateful hybrid framework that combines classical commitment-based challenge-response authentication with BB84-based quantum-channel monitoring. QIAP uses a dual-branch verification structure inspired by rectilinear and diagonal basis selection. In the rectilinear branch, the prover opens a hash-based commitment and the verifier checks consistency with the registered round token. In the diagonal branch, the prover returns an HMAC tag bound to the verifier nonce, round identifier, and submitted commitment without disclosing the round-specific sub-secret. Under the stated hash, HMAC, freshness, secure-registration, protected-storage, and high-entropy-secret assumptions, QIAP provides computational resistance to the modeled wrong-secret and replay attempts and protects the long-term master secret from direct recovery. After successful authentication, the BB84 module estimates the quantum bit error rate (QBER) and aborts the session when the measured value reaches or exceeds the configured threshold. In the reported simulation, no successful authentication was observed among 1,000 tested wrong-secret attempts per branch. The baseline and full intercept-resend conditions produced mean QBER values of approximately 0.02 and 0.25, respectively. The classical authentication stage required approximately 0.6 ms, and the implemented authentication messages required approximately 113 bytes per round. These results indicate that QIAP can provide a lightweight hybrid framework for combining secret-based identity verification with QBER-based channel-disturbance assessment under the stated threat model.
An information-theoretic analysis of secure authentication based on Quantum Physically Unclonable Functions (QPUF) is presented in this paper. The proposed model employs a secret key generated through QPUF to authenticate pre-enrolled user and device identities while maintaining secrecy and limiting privacy leakage. We analyze the system's robustness against an active adversary who exploits publicly available data to impersonate legitimate users with fraudulent inputs. Our analysis focuses on characterizing the capacity region of the adversary's false acceptance exponent alongside the privacy leakage under reliability conditions. We further demonstrate that the achievable capacity region in the quantum domain surpasses that of classical systems. Additionally, we derive an optimal trade-off among the false acceptance exponent, public storage rate, and privacy leakage rate, offering key insights into the system's asymptotic performance.
Unconditional security in Quantum Key Distribution (QKD) relies on authenticating the identities of users involved in key distribution. While classical identity authentication schemes were initially utilized in QKD implementations, concerns regarding their vulnerability have prompted the exploration of Quantum Identity Authentication (QIA) protocols. In this study, we introduce a new protocol for QIA, derived from the concept of controlled secure direct quantum communication. Our proposed scheme facilitates simultaneous authentication between two users, Alice and Bob, leveraging Bell states with the assistance of a third party, Charlie. Through rigorous security analysis, we demonstrate that the proposed protocol withstands various known attacks, including impersonation, intercept and resend and impersonated fraudulent attacks. Additionally, we establish the relevance of the proposed protocol by comparing it with the existing protocols of similar type.
The quantum Internet promises to revolutionize computing, communications, sensing, and security by leveraging quantum entanglement. In this context, quantum repeaters play a crucial role by performing entanglement swapping to extend entanglement across distant nodes. However, malicious repeaters can retain entangled pairs, enabling man-in-the-middle attacks that compromise security. Quantum Identity Authentication (QIA) protocols aim to mitigate this threat by verifying the legitimacy of communicating parties. However, existing QIA protocols rely on unrealistic assumptions, such as noise-free environments or static noise profiles, that do not reflect the nature of real-world quantum networks. Such noise can cause benign sessions to be flagged as attacks or allow attacks to go undetected. To address these limitations, we propose a machine learning-enhanced QIA framework designed for noisy quantum environments. The protocol performs random authentications during communication sessions using parameters derived from a shared secret key. These parameters determine the preparation and measurement of authentication qubits, known only to legitimate users. A trained machine learning model analyzes physical-layer information (e.g., entanglement fidelity, routing path) and protocol-level data (e.g., basis selection, encoding bit, and measurement outcomes) to detect malicious behavior under fluctuating noise conditions. We evaluate several attack detection models and identify XGBoost as the most effective, achieving 97.18% accuracy and an F1-score of 0.96. The proposed XGBoost-enhanced QIA protocol detects attacks within the first authentication round, achieving a 100% detection and a 1.7% false alarm rate. This reflects a 16.1% improvement in detection rate and a 92.5% reduction in false alarms compared to the entanglement-based QIA benchmark.
Quantum key distribution (QKD) is a method that enables secure communication between two parties by applying the ideas of quantum physics. By minimizing information leakage that can happen during the key generation process, privacy amplification is a technique used to improve the security of QKD. The technique involves processing the raw key obtained from QKD through a randomization procedure to remove any residual information that may have been leaked during the quantum transmission. While privacy amplification can significantly improve the security of QKD, the effectiveness of the technique is limited by the quality of the initial raw key. The BB84 QKD protocol has been improved with the proposed En-BB84 protocol, which includes built-in authentication and integrity checks. The En-BB84 protocol ensures secure distribution of secret keys and protects against tampering by attackers. Key distillation and error correction techniques are employed to extract a shorter, more secure shared secret key and correct errors introduced during qubit transmission. The protocol utilizes a four-state QKD approach, expanding on the traditional two-state scheme of BB84. A simulation of the En-BB84 protocol is demonstrated using a quantum circuit implemented with Qiskit in Python. The circuit employs various gates and operations, including Hadamard, CX, controlled swap, and RZ gates, to achieve encoding and error correction. Furthermore, we have designed a better protocol with improved error rates by incorporating improvisations on the BB84 protocol. Experimental results indicate the successful integration of the B92 error correction scheme into the modified BB84 protocol, enhancing the security and performance of QKD systems.
Quantum Key Distribution (QKD) is increasingly recognized as a robust solution to the vulnerabilities posed by quantum computing to classical encryption systems. This paper presents a comprehensive investigation of the BB84 protocol, the foundational QKD scheme, through simulated quantum communication using IBM’s Qiskit framework. The study models quantum key exchange under both ideal and adversarial conditions, including channel noise and intercept-resend attacks. The Quantum Bit Error Rate (QBER) was measured as a function of noise intensity and eavesdropping, confirming that QBER increases predictably in compromised channels. A threshold of 11% QBER was used to determine the viability of secure key generation. Final key retention rates were analyzed across multiple channel scenarios, revealing BB84’s sensitivity to both photon loss and adversarial interference.\n\nSecurity vulnerabilities such as photon-number-splitting and detector blinding were assessed, and countermeasures including decoy-state protocols and authenticated classical channels were proposed. Four key performance graphs were generated to visualize system behavior under realistic operational conditions. The results support BB84’s theoretical advantage in ensuring information-theoretic security while acknowledging real-world limitations in transmission range and hardware reliability. The paper concludes by addressing future improvements in QKD systems, including satellite-based distribution, quantum repeaters, and device-independent implementations. Through simulation-driven analysis, this study validates BB84 as a practical defense against quantum-enabled attacks and underscores the need for continued development and standardization in post-quantum cryptographic infrastructure.