Key agreement protocols based on neural synchronization with Tree Parity Machines (TPMs) offer promising security advantages: they do not rely on trapdoor functions, making them resistant to quantum attacks, and they avoid the need for specialized hardware required by quantum-based schemes. Nevertheless, these protocols face a significant vulnerability: the large number of public message exchanges required for synchronization increases the risk that an attacker, acting as a Man-in-the-Middle, can successfully synchronize their own TPMs with those of the legitimate parties and ultimately recover the shared key. Motivated by the need to reduce this risk, we propose a novel probabilistic protocol that enables two parties to securely estimate the size of the shared key during intermediate steps, without revealing any key material. This estimation allows the protocol to terminate as soon as sufficient key material has been established, thereby reducing the number of synchronization rounds and limiting the opportunity for an attacker to synchronize. We integrate our estimation mechanism into a neural key agreement protocol and evaluate its performance and security, demonstrating improved efficiency and enhanced resistance to attacks compared to existing approaches.
Key agreement protocols based on neural synchronization with Tree Parity Machines (TPMs) offer promising security advantages: they do not rely on trapdoor functions, making them resistant to quantum attacks, and they avoid the need for specialized hardware required by quantum-based schemes. Nevertheless, these protocols face a significant vulnerability: the large number of public message exchanges required for synchronization increases the risk that an attacker, acting as a Man-in-the-Middle, can successfully synchronize their own TPMs with those of the legitimate parties and ultimately recover the shared key. Motivated by the need to reduce this risk, we propose a novel probabilistic protocol that enables two parties to securely estimate the size of the shared key during intermediate steps, without revealing any key material. This estimation allows the protocol to terminate as soon as sufficient key material has been established, thereby reducing the number of synchronization rounds and limiting the opportunity for an attacker to synchronize. We integrate our estimation mechanism into a neural key agreement protocol and evaluate its performance and security, demonstrating improved efficiency and enhanced resistance to attacks compared to existing approaches.
Key agreement in open networks must not only resist quantum computing threats but also establish keys and authenticate counterparties without explicitly revealing identities. Existing solutions often rely on additional certificates or explicit signature-based authentication or require multiple rounds of interaction and complex state management, thereby imposing burdens on deployment and scalability. To address this, we propose a key agreement protocol based on a post-quantum identity-matching scheme, which unifies identity binding, implicit authentication, and session key establishment into a single key agreement process. Specifically, the initiator generates a ciphertext based on the peer’s identity and embeds session-related information within it, enabling the recipient to verify the peer’s identity and confirm the consistency of the key while decrypting and recovering the shared material. Additionally, bidirectional confirmation messages are used to eliminate negotiation deviations such as the sharing of unknown keys. Furthermore, a version control mechanism is introduced as a synchronization tag for key evolution, allowing the session key to be naturally updated within a predetermined time window. Concurrently, a revocation list maintained by a blockchain is established, enabling distributed verification and auditing of revocation status. This supports key update and revocation management without increasing the number of negotiation rounds. Performance evaluations and security analyses indicate that the protocol incurs a single-end computational overhead of less than 100 μs and a communication overhead of approximately 17.1 KB, trading moderate performance overhead for strong security semantics.
The article discusses a key reconciliation protocol for quantum key distribution (QKD) systems based on Tree Parity Machines (TPM). The idea of transforming key material into neural network weights is presented. Two experiments were conducted to study how the number of synchronization iterations and the amount of leaked information depend on the quantum bit error rate (QBER) and the range of neural network weights. The results show a direct relationship between the average number of synchronization iterations and QBER, an increase in iterations when the weight range is expanded, and a reduction in leaked information as the weight range increases. Based on these results, conclusions are drawn regarding the applicability of the protocol and the prospects for further research on neural cryptographic methods in the context of key reconciliation.
This paper presents a novel approach to enhancing the security of error correction in quantum key distribution by introducing randomization into the update rule of Tree Parity Machines. Two dynamic update algorithms—dynamic_rows and dynamic_matrix—are proposed and tested. These algorithms select the update rule quasi-randomly based on the input vector, reducing the effectiveness of synchronization-based attacks. A series of simulations were conducted to evaluate the security implications under various configurations, including different values of K, N, and L parameters of neural networks. The results demonstrate that the proposed dynamic algorithms can significantly reduce the attacker’s synchronization success rate without requiring additional communication overhead. Both proposed solutions outperformed hebbian, an update rule-based synchronization method utilizing the percentage of attackers synchronization. It has also been shown that when the attacker chooses their update rule randomly, the dynamic approaches work better compared to random walk rule-based synchronization, and that in most cases it is more profitable to use dynamic update rules when an attacker is using random walk. This study contributes to improving QKD’s robustness by introducing adaptive neural-based error correction mechanisms.
This paper proposes a novel distributed key agreement protocol leveraging the unique properties of quantum entanglement. The core concept involves two parties sharing a pre-established entangled state, performing correlated measurements, and directly using the measurement outcomes to generate a shared secret key. This eliminates the need for classical communication channels, significantly enhancing security by mitigating the risk of eavesdropping during key transmission and reducing latency associated with classical message exchange. The protocol addresses key challenges in entanglement-based systems, namely maintaining entanglement fidelity and ensuring synchronized measurement processing. We outline the theoretical framework, detailing the mathematical formulation of the key generation process and highlighting the critical aspects of entanglement distribution and measurement protocols. This approach represents a fundamental shift in distributed key agreement, moving towards inherently secure and efficient quantum communication systems.
Quantum-safe public key exchange protocols face significant challenges in hardware- and software-based approaches. Quantum key distribution, which relies on specialized quantum hardware, presents a significant barrier to widespread adoption due to its high cost and limited scalability. Conversely, software-based solutions using post-quantum algorithms introduce complications, such as increased resource demands and larger cipher-texts. Furthermore, the security of these post-quantum algorithms remains relatively untested, which has led to the emerging trend of hybrid deployment, combining clas-sical and quantum-resistant techniques to hedge against potential vulnerabilities. Recently, Arqit proposed a quantum-secure symmet-ric key agreement (SKA) protocol, claiming that it is lightweight and scalable [1] to address these problems. However, their proprietary solution is not available for independent analysis. To evaluate the performance and scalability of quantum-secure SKA techniques, we develop variations of the SKA protocol using open-source and accessible components in this work. To analyze quantum-secure SKA scheme, we imple-mented an SKA technique that involves a hybrid mech-anism, leveraging secret strings distributed through a combination of existing classical and quantum public key pairs during the initial key exchange. We analyze our scheme and demonstrate that it incurs minimal performance overhead, with only 99ms for purely quantum SKA and 199ms for the hybrid version, compared to the classical SKA protocol. We also show that our scheme remains robust under various network conditions, including delays, packet losses, and bandwidth variations, maintaining small and consistent overheads. We also show that this solution is scalable, with an overhead of only one second for every additional five concurrent users. This performance improves significantly with increased computational resources-achieving a 50-60% improvement when scaling from two to four CPUs. Additionally, our security evaluations confirm that the protocol provides consistent and sufficient randomness throughout the key agreement process, ensuring quantum-resistance at every stage.
Abstract The semi-quantum key agreement (SQKA) protocol enables classical participants to complete key agreement with limited quantum capabilities. The previous semi-quantum key agreement protocols required the classical party to have the ability to measure qubits, and share a key before the protocol began. This paper proposes a SQKA protocol that allows semi-quantum participants to use single photons for key negotiation with the help of a semi-honest third party (TP). Unlike previous approaches, this protocol further reduces the quantum capability requirements for participants and eliminates the need for prior key sharing. Furthermore, through security analysis and multi-party expansion, the protocol can resist external attacks such as the intercept-resend attack, measure-resend attack, entangle-measure attack. Additionally, it can be applied to scenarios involving different numbers of participants.