Measuring the effect of AES encryption on VoWLAN QoS

This paper focuses on the quality parameters of Voice over Wireless Local Area Network (VoWLAN) and how they are affected by the addition of end-to-end encryption using Advanced Encryption Standard (AES) of 128-bits and 256-bits block sizes. An experimental setup was made to evaluate mean and maximum delay and jitter, and packet loss. These quality parameters were measured for non-encrypted streams, AES 128-bit encrypted streams, AES 256-bit encrypted streams for the CODECs; G,711, G.729, and G.723.1. The encryption was applied to Real-time Transport Protocol (RTP) payload. The tests showed that encryption affects the delay noticeably for high-bit-rate CODECs, such as G.711. G.729 streams delay was less affected, and the delay of G.723.1 streams was even less affected. Jitter and packet loss were not highly affected by the addition of encryption. The results also showed that 256-bit AES encryption causes less delay despite the fact that it needs longer calculations that the 128-bit AES. This is due to the fact that larger block size causes less number of repetitions to encrypt a complete payload field of an RTP packet. It was also concluded that the use of G.723.1 with AES encryption is more recommended in VoWLAN because it has better quality measures.