When the network is homogeneous, choosing the cipher type for a packet telephony application is simple. It is clear that stream ciphers perform better than block ciphers over landline, circuit-switched networks, since loss is negligible in these networks but corruption is not. Likewise, it is also clear that block ciphers perform better than stream ciphers over landline, packet-switched networks, since corruption is negligible in these networks but loss is not [9]. However, the choice of cipher is not so clear for a heterogeneous internetwork containing a mix of packet and circuit-switched networks. Additionally, this issue becomes even more confounded when heterogeneous internetwork also consists of wireless links. Existing encryption systems will degrade performance in a heterogeneous internetwork because such internetworks have appreciable loss and corruption. Thus, the error properties would degrade the subjective quality of the packet telephony application. In this paper we prese...
Ashraf D. Elbayoumy, Simon J. Shepherd