Quantum-secure Group-based Communication with Post-quantum Cryptography

Quantum computing threatens traditional cryptographic methods, particularly attacks posed by the execution of the Shor's and Grover's quantum algorithms. These algorithms have the capability of solving the hard mathematical problem on which the current cryptography are based on. This has magnified the imperative need for quantum-resistant security solutions, which brought post-quantum cryptography (PQC) and quantum-key-distribution (QKD), two technologies resistant to the quantum threat. PQC is a set of cryptographic algorithms designed to secure digital communication and data against potential attacks by quantum computers, using mathematical problems that are believed to be too difficult even for quantum computers to solve. PQC is especially attractive due to their capability of being implemented in the current electronic technology. Group-based secure communication is relevant for many emerging applications. Group-based communication, traditionally dependent on classical cryptographic techniques susceptible to quantum threats, necessitates an urgent transition to make it quantum-secure. This thesis presents two innovative schemes geared towards achieving quantum-secure group-based communication based on post-quantum cryptography: a contributory model (PQC GAKE) and a distributed model (PQC SLIMCAST). Both protocols take advantage of PQC algorithms, notably those recognized in the NIST standardization process, to ensure data transmission across multiple nodes that meets rigorous standards of confidentiality, integrity, and authenticity. These schemes predominantly employ PQC Key-Encapsulation-Mechanism (KEM) algorithms for key generation and PQC signature (SIG) algorithms for authentication, subsequently enabling the group key derivation or distribution (GKD) process via key-compiler or key-wrapping techniques. The research methodology covers a software simulation model that allows for up to 300 nodes, integrates PQC algorithm implementations, and utilizes a dedicated virtual benchmarking environment. Findings show that the contributory protocol PQC GAKE surpasses our distributed protocol PQC SLIMCAST in group key distribution (GKD), particularly with large node counts, but faces prolonged rekeying durations. Furthermore, it was found that the quantum-secure group-based communication is efficient. The impact of PQC KEM and SIG on the performance of GKD, such as time to distribute key to every node, is found to be minimal.