Hybrid ECDH–Paillier Key Processing and Session-Oriented Key Management in Asterisk-Based VoIP Networks

The increasing adoption of Voice over IP (VoIP) technologies in enterprise and distributed communication environments underscores the importance of practical approaches to cryptographic key handling and management during session establishment. This paper presents an experimental architecture that combines the Elliptic Curve Diffie–Hellman (ECDH) protocol for key generation, the encryption and decryption of specific ECDH public-key fragments using the Paillier cryptosystem, data verification via a database, and session-specific key management operations. An experimental implementation of this key-handling process based on the ECDH and Paillier protocols was developed using Asterisk, Linphone, Python, and MariaDB. Functional testing confirmed the system’s capability to register SIP clients, perform cryptographic operations, verify decrypted key fragments, and establish voice connections. The complete processing cycle for a single session took approximately 2.5–10 s. Furthermore, a classifier based on the Random Forest algorithm was integrated to assess Quality of Service (QoS) in the VoIP system, utilizing Real-time Transport Protocol (RTP) parameters such as packet loss and jitter. The classifier achieved 100% accuracy on the original test dataset and approximately 99.03% accuracy in the reported noise injection experiment, with an average prediction time of approximately 16.4 ms. These results demonstrate the feasibility of integrating cryptographic key-handling mechanisms and QoS classification within a VoIP network.