Uvoip: Cross-layer Optimization of Buffer Operations for Providing Secure Voip Services on Constrained Embedded Devices

In this paper, we present an optimized implementation of secure VoIP protocol stack so that the stack would fit into the memory and computation budget of constrained embedded systems. The novel approach that we take to achieve this is to perform cross-layer optimization of buffers and buffer operations. Buffers and buffer operations are involved in playback, capture, codec transformations, and network I/O. Following this approach, we have implemented VoIP application functions, RTP, and Secure RTP protocols in a tightly integrated and highly optimized manner, on the top of the embedded TCP/IP stack, uIP. We call the protocol stack thus constructed, the uVoIP stack. We have tested the uVoIP stack in GNU/Linux Operating System using tunnel device for sending and receiving raw packets.