QoS evaluation in VoIP software with and without Blowfish encryption module

Voice over Internet Protocol (VoIP) represents considerable cost savings in comparison with traditional phone lines. VoIP, operates in the IP network, therefore it inherits all network security and safety problems. Consequently, implementing VoIP without any security mechanisms produces many risks and it does not provide any guaranty of privacy of information and calls. It is possible to use the encryption in order to secure the calls. However, VoIP is a real time application and using encryption degrades the quality of service (QoS) by increasing the delay and the jitter. In this paper, we propose the use of the Blowfish encryption algorithm to encrypt the audio communication between the VoIP clients as the used algorithm was previously compared to the Advanced Encryption Standard (AES) algorithm, and it was shown that it is faster and it offers a better throughput. In this study, we developed VoIP clients and we performed many experimental tests on these clients with the implemented algorithm in order to provide security without degradation of the quality of calls. The obtained results show an acceptable compromise among all performance parameters and they are considered motivating and very encouraging.