In recent years, noticeable progress has been made in the development of quantum equipment, reflected through the number of successful demonstrations of Quantum Key Distribution (QKD) technology. Although they showcase the great achievements of QKD, many practical difficulties still need to be resolved. Inspired by the significant similarity between mobile ad-hoc networks and QKD technology, we propose a novel quality of service (QoS) model including new metrics for determining the states of public and quantum channels as well as a comprehensive metric of the QKD link. We also propose a novel routing protocol to achieve high-level scalability and minimize consumption of cryptographic keys. Given the limited mobility of nodes in QKD networks, our routing protocol uses the geographical distance and calculated link states to determine the optimal route. It also benefits from a caching mechanism and detection of returning loops to provide effective forwarding while minimizing key consumption and achieving the desired utilization of network links. Simulation results are presented to demonstrate the validity and accuracy of the proposed solutions.

Intensive work on quantum computing has increased interest in quantum cryptography in recent years. Although this technique is characterized by a very high level of security, there are still challenges that limit the widespread use of quantum key distribution. One of the most important problems remains secure and effective mechanisms for the key distillation process. This article presents a new idea for a key reconciliation method in quantum cryptography. This proposal assumes the use of mutual synchronization of artificial neural networks to correct errors occurring during transmission in the quantum channel. Users can build neural networks based on their own string of bits. The typical value of the quantum bit error rate does not exceed a few percent; therefore, the strings are similar and also users’ neural networks are very similar at the beginning of the learning process. It has been shown that the synchronization process in the new solution is much faster than in the analogous scenario used in neural cryptography. This feature significantly increases the level of security because a potential eavesdropper cannot effectively synchronize their own artificial neural networks in order to obtain information about the key. Therefore, the key reconciliation based on the new idea can be a secure and efficient solution.

In the face of advancing quantum computing capabilities posing significant threats to current cryptographic protocols, the need for post-quantum cryptography has become increasingly urgent. This paper presents a comprehensive analysis of the performance of various post-quantum cryptographic algorithms specifically applied to digital signatures. It focuses on the implementation and performance analysis of selected algorithms, including CRYSTALS-Dilithium, Falcon, and SPHINCS+, using the liboqs library. Performance tests reveal insights into key pair generation, file signing, and signature verification processes. Comparative tests with the well-known and popular RSA algorithm highlight the trade-offs between security and time efficiency. The results can help to select secure and efficient ciphers for specific 5G/6G services.

The advent of quantum computing presents a significant threat to the security of asymmetric cryptographic algorithms, necessitating the adoption of new cryptographic mechanisms resilient to quantum-based attacks. This need is particularly critical for applications that rely exclusively on public-key cryptography, such as digital signatures. This paper presents a comprehensive analysis of the performance of various post-quantum cryptographic algorithms, focusing specifically on NIST-standardized digital signature algorithms—SPHINCS+ and Dilithium—and their practical implementations. The study evaluates these algorithms across different programming languages to identify optimal environments for diverse applications. Comparative analyses with the widely used RSA algorithm reveal that the computational cost of adopting post-quantum cryptographic systems is relatively low. Notably, some post-quantum algorithms demonstrate performance advantages over classical RSA in specific scenarios.

This paper describes a new concept of security measurement in quantum cryptography (QC). The most popular quantum key distribution protocol BB84 and the key distillation process are briefly introduced first. Next, a new concept of entropy of security in QC is proposed, and a unique measure of security is defined. Using this quantitative approach to security, it is possible to manage security and personalize services based on QC. Two different security levels are defined: the basic security level and the advanced security level. This differentiation of security enables us to choose the appropriate security level for specific end-users' requirements and needs. The last section presents the results of simulation experiments which verified the proposed solution.

Neural cryptography is the application of artificial neural networks (ANNs) in the subject of cryptography. The functionality of this solution is based on a tree parity machine (TPM). It uses ANNs to perform secure key exchange between network entities. This brief proposes improvements to the synchronization of two TPMs. The improvement is based on learning ANN using input vectors that have a wider range of values than binary ones. As a result, the duration of the synchronization process is reduced. Therefore, TPMs achieve common weights in a shorter time due to the reduction of necessary bit exchanges. This approach improves the security of neural cryptography.