| The public telephone network has been evolving from manually switched wires carrying analog encoded voice of the 19th century to an automatically switched grid of copper-wired, fiber optical and radio linked portions carrying digitally encoded voice and other data. Simultaneously, as our security consciousness increases, so does our desire to keep our conversations private. Applied to the traffic traversing the globe on the public telephone network, privacy requires that the telephone companies provide a service whereby unintended third parties are unable to access other's signals. However, existing design of the public telephone network is susceptible to eavesdropping on its voice stream. Consequently, any wire tapper can listen to supposedly private conversations.; In order to prevent such eavesdropping, this dissertation describes a new voice privacy architecture and its protocols developed to provide end-to-end voice privacy service with telephone and subscriber authentication; the design only requires a slight modification of the existing public telephone network infrastructures. The architecture consists of certificate authorities (CA), authentication centers ( AC) and telephone sets with cryptographic capabilities on top of the existing public telephone network infrastructure. In addition, this dissertation discusses how these entities and necessary signaling mechanisms can be implemented using the transaction capabilities application layer (TCAP) of the signaling system seven (SS7) protocol and the D channel of the digital subscriber line (DSL) connecting the telephone to the SS7 network.; Using OPNet Modeler software and published specifications, the dissertation shows that the connection establishing delay for such voice privacy is approximately 17, 19, and 21 seconds for local/regional, long distance, and international connection, respectively. This delay is due to both subscriber and telephone authentication, and is only four times longer than the typical normal call connection establishing delay. This makes voice privacy service comparable to existing intelligent services provided over public telephones. |
