Cryptology ePrint Archive: Report 2015/099

Universally Composable Firewall Architectures using Trusted Hardware

Dirk Achenbach and Jörn Müller-Quade and Jochen Rill

Abstract: Network firewalls are a standard security measure in computer networks that connect to the Internet. Often, ready-to-use firewall appliances are trusted to protect the network from malicious Internet traffic. However, because of their black-box nature, no one can be sure of their exact functionality. We address the possibility of actively compromised firewalls. That is, we consider the possibility that a network firewall might collaborate with an outside adversary to attack the network. To alleviate this threat, we suggest composing multiple firewalls from different suppliers to obtain a secure firewall architecture. We rigorously treat the composition of potentially malicious network firewalls in a formal model based on the Universal Composability framework. Our security assumption is trusted hardware. We show that a serial concatenation of firewalls is insecure even when trusted hardware ensures that no new packages are generated by the compromised firewall. Further, we show that the parallel composition of two firewalls is only secure when the order of packets is not considered. We prove that the parallel composition of three firewalls is insecure, unless a modified trusted hardware is used.

Category / Keywords: cryptographic protocols / Formal Models, Universal Composability

Original Publication (in the same form): Cryptography and Information Security in the Balkans Lecture Notes in Computer Science Volume 9024, 2015, pp 57-74

Date: received 10 Feb 2015, last revised 19 Aug 2015

Contact author: dirk achenbach at kit edu

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Version: 20150819:105319 (All versions of this report)

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