Transport Security for the next Generation Mobile Terminals

The objective of this thesis is to investigate and compare different possible solutions for achieving secure communications using the mobile terminals for the next generation cellular networks. The trend is that these terminals will become more equivalent to today’s Personal Digital Assistants (PDAs) regarding the possibilities of interaction. Different possibilities for achieving secure communications exist today. Different security protocols works at different layers in the IP-stack. An evaluation of the protocols was therefore done as a part of the thesis. I have investigated how the position of the security protocol in the IP-stack affects the applications that are to use the security protocol. When using cellular networks, such as the GSM network, the latency in the network together with the available bandwidth may impose difficulties in using some security protocols. A high latency, for example, introduces long negotiation and setup times. To investigate the characteristics of using a GSM connection to the Internet, some tests have been carried out. The purposes of the tests were to find out how the setup and negotiation times, and the transfer rates are affected by using a cellular network. The tests I conducted shows that the latency in the GSM network is high, about one second. Therefore, protocols that use few but larger messages are better than protocols that use many small messages.