МЕТОДИ ЗАБЕЗПЕЧЕННЯ КВАНТОВО-АДАПТИВНОЇ БЕЗПЕКИ ГІБРИДНИХ КРИПТОГРАФІЧНИХ ПРОТОКОЛІВ У МЕРЕЖАХ НОВОГО ПОКОЛІННЯ

This article investigates methods for ensuring the quantum-adaptive security of hybrid cryptographic protocols in next-generation networks. 5G/6G and IoT networks necessitate the integration of classical and post-quantum algorithms. However, standard protocols combining ECDH with CRYSTALS-Kyber or CRYSTALS-Dilithium require formal security assessments. Current approaches primarily consider non-adaptive quantum adversaries, which limits their practical applicability in multi-session and dynamic environments. The paper proposes a model of a quantum-adaptive adversary. This model integrates the adversary's classical and quantum resources, an adaptive attack strategy, and a quantum-accessible oracle. It allows for the formalization of superposition queries and multi-step interactions with the protocol. A mathematical model of a hybrid handshake protocol is introduced, where the session key is formed by combining classical and post-quantum components via a Key Derivation Function. An upper bound for the adversary's advantage is derived, accounting for both the classical and post-quantum components of the protocol. To enhance resilience, three primary methods are proposed. The first is downgrade-resistant fixation of protocol parameters with cryptographic confirmation. The second is dynamic management of key parameters and cryptographic primitives based on an integrated risk function, which accounts for the adversary's quantum resources, network load, and attack activity. The third is compositional protocol verification considering multi-session and multi-level handshake phases, enabling the formalization of composability and the assessment of multi-level resilience. An integral metric of quantum-adaptive resilience is proposed, accounting for security, complexity, and adaptability. The results provide a scientific foundation for “harvest-now, decrypt-later” risk analysis.