Abstract-Session Initiation Protocol (SIP) has emerged as the predominant protocol for setting up, maintaining, and terminating Voice over Internet Protocol (VoIP) sessions. In spite of the security mechanisms that it offers, several attacks are being made on the SIP architecture. In this paper we take a proactive approach and highlight the importance of testing SIP from a security perspective. We first give a brief introduction to some of the most common attacks on SIP. We then describe a framework to effectively test several security aspects of a SIP network and thereby help mitigate such attacks. We also present a genetic algorithm that we developed and used to generate data in our fuzz testing. Finally, we present the results of some tests performed on popular SIP devices using our framework.

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A Sagnac interferometer’s ring structure causes electromagnetic waves traversing it to periodically encounter the same optical elements. Due to this discrete translational symmetry, the frequency spectrum of the clockwise and counter-clockwise modes acquire a band structure with a characteristic band gap. When the interferometer is rotated, an additional non-reciprocal phase shift between the counter propagating modes arises and it results in the loss of time reversal symmetry. While prior understanding of the impact of Sagnac rotation on the band structure exists, the prevalence of topological geometric phase in Sagnac interferometer under rotation has not been prominently discussed. We propose a coupled mode theory with the required time reversal symmetry properties which influences the Berry curvature and we show that it leads to the accumulation of Berry phase with tunable topological charge.