Institute of Computer Science
Georg-August-Universität Göttingen
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Description
In the current communication infrastructure a variety of services are already based on the Internet Protocol (IP) and effort is taken to put the mobile communication as well into the IP framework. Many of these services like voice over IP or online banking require an increased level of security and privacy, and therefore demanding a wide application of security suits as IPSec. These connections are typically secured by keys derived from a key negotiation process run with the IKEv2 key negotiation protocol. This process is computationally heavy; ideally it should be performed as rarely as possible. The computational complexity could grow to a severe problem in mobile environments where a base station is handling hundreds or thousands of mobile nodes and the gateway fails for any reason. If the gateway fails and recovers later, all IPSec capable devices will try to resume their session immediately by renegotiating keys and potentially overload the gateways resources by doing that in parallel. Furthermore the total number of clients a base station can handle is reduced when sessions to end host fail temporarily due to e.g. communication distortions etc. Every time re-keying is necessary. In this thesis a server side stateless IPSec session resumption approach developed by Sheffer et al. is presented and analysed. The sessions state including the master secret as the source for further keying material is stored in an encrypted ticket which can later be used to quickly resume the session. A formal security analysis based on CSP algebra interpreted with the CasperFDR toolkit was performed and it could be shown that no new security threats are introduced by altering the IKEv2 communication sequence and storing the state inside a ticket. Furthermore, a prototype of the ticket based session resumption was implemented into an existing open source linux IKEv2 daemon and the performance evaluation showed a significant reduction in the session resumption time. Overall, this thesis illustrates the new ticket based session resumption approach, verifies it via a formal security toolkit and proves the significant reduction of the time required to resume a session in a prototype implementation. |
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Requirements
Knowledge of network security protocols and formal verification tools; experience of C/C+ network programming. |
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Links
Completed master thesis can be found here. |
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