DTLS Performance in Duty-Cycled Networks

The Datagram Transport Layer Security (DTLS) protocol is the IETF standard for securing the Internet of Things. The Constrained Application Protocol, ZigBee IP, and Lightweight Machine-to-Machine (LWM2M) mandate its use for securing application traffic. There has been much debate in both the standardization and research communities on the applicability of DTLS to constrained environments. The main concerns are the communication overhead and latency of the DTLS handshake, and the memory footprint of a DTLS implementation. This paper provides a thorough performance evaluation of DTLS in different duty-cycled networks through real-world experimentation, emulation and analysis. In particular, we measure the duration of the DTLS handshake when using three duty cycling link-layer protocols: preamble-sampling, the IEEE 802.15.4 beacon-enabled mode and the IEEE 802.15.4e Time Slotted Channel Hopping mode. The reported results demonstrate surprisingly poor performance of DTLS in radio duty-cycled networks. Because a DTLS client and a server exchange more than 10 signaling packets, the DTLS handshake takes between a handful of seconds and several tens of seconds, with similar results for different duty cycling protocols. Moreover, because of their limited memory, typical constrained nodes can only maintain 3-5 simultaneous DTLS sessions, which highlights the need for using DTLS parsimoniously.Comment: International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC - 2015), IEEE, IEEE, 2015, http://pimrc2015.eee.hku.hk/index.htm

Managing Access Control in Virtual Private Networks

Virtual Private Network technology allows remote network users to benefit from resources on a private network as if their host machines actually resided on the network. However, each resource on a network may also have its own access control policies, which may be completely unrelated to network access. Thus users� access to a network (even by VPN technology) does not guarantee their access to the sought resources. With the introduction of more complicated access privileges, such as delegated access, it is conceivable for a scenario to arise where a user can access a network remotely (because of direct permissions from the network administrator or by delegated permission) but cannot access any resources on the network. There is, therefore, a need for a network access control mechanism that understands the privileges of each remote network user on one hand, and the access control policies of various network resources on the other hand, and so can aid a remote user in accessing these resources based on the user\u27s privileges. This research presents a software solution in the form of a centralized access control framework called an Access Control Service (ACS), that can grant remote users network presence and simultaneously aid them in accessing various network resources with varying access control policies. At the same time, the ACS provides a centralized framework for administrators to manage access to their resources. The ACS achieves these objectives using VPN technology, network address translation and by proxying various authentication protocols on behalf of remote users

Scalable Security Mechanisms for the Internet

The design principle of restricting local autonomy only where necessary for global robustness has led to a scalable Internet. Unfortunately, this scalability and capacity for distributed control has not been achieved in the mechanisms for specifying and enforcing security policies. The STRONGMAN system described in this paper demonstrates three new approaches to providing efficient local policy enforcement complying with global security policies. First is the use of a compliance checker to provide great local autonomy within the constraints of a global security policy. Second is a mechanism to compose policy rules into a coherent enforceable set, e.g., at the boundaries of two locally autonomous application domains. Third is the lazy instantiation of policies to reduce the amount of state enforcement points need to maintain. We demonstrate the use of these approaches in the design, implementation and measurements of a distributed firewall

Separation of SSL protocol phases across process boundaries

Secure Sockets Layer is the de-facto standard used in the industry today for secure communications through web sites. An SSL connection is established by performing a Handshake, which is followed by the Record phase. While the SSL Handshake is computationally intensive and can cause of bottlenecks on an application server, the Record phase can cause similar bottlenecks while encrypting large volumes of data. SSL Accelerators have been used to improve the performance of SSL-based application servers. These devices are expensive, complex to configure and inflexible to customizations. By separating the SSL Handshake and the Record phases into separate software processes, high availability and throughput can be achieved using open-source software and platforms. The delegation of the SSL Record phase to a separate process by transfer of necessary cryptographic information was achieved. Load tests conducted, showed gains with the separation of the Handshake and Record phases at nominal data sizes and the approach provides flexibility for enhancements to be carried out for performance improvements at higher data sizes

Greenpass Client Tools for Delegated Authorization in Wireless Networks

Dartmouth\u27s Greenpass project seeks to provide strong access control to a wireless network while simultaneously providing flexible guest access; to do so, it augments the Wi-Fi Alliance\u27s existing WPA standard, which offers sufficiently strong user authentication and access control, with authorization based on SPKI certificates. SPKI allows certain local users to delegate network access to guests by issuing certificates that state, in essence, he should get access because I said it\u27s okay. The Greenpass RADIUS server described in Kim\u27s thesis [55] performs an authorization check based on such statements so that guests can obtain network access without requiring a busy network administrator to set up new accounts in a centralized database. To our knowledge, Greenpass is the first working delegation-based solution to Wi-Fi access control. My thesis describes the Greenpass client tools, which allow a guest to introduce himself to a delegator and allow the delegator to issue a new SPKI certificate to the guest. The guest does not need custom client software to introduce himself or to connect to the Wi-Fi network. The guest and delegator communicate using a set of Web applications. The guest obtains a temporary key pair and X.509 certificate if needed, then sends his public key value to a Web server we provide. The delegator looks up her guest\u27s public key and runs a Java applet that lets her verify her guests\u27 identity using visual hashing and issue a new SPKI certificate to him. The guest\u27s new certificate chain is stored as an HTTP cookie to enable him to push it to an authorization server at a later time. I also describe how Greenpass can be extended to control access to a virtual private network (VPN) and suggest several interesting future research and development directions that could build on this work.My thesis describes the Greenpass client tools, which allow a guest to introduce himself to a delegator and allow the delegator to issue a new SPKI certificate to the guest. The guest does not need custom client software to introduce himself or to connect to the Wi-Fi network. The guest and delegator communicate using a set of Web applications. The guest obtains a temporary key pair and X.509 certificate if needed, then sends his public key value to a Web server we provide. The delegator looks up her guest\u27s public key and runs a Java applet that lets her verify her guests\u27 identity using visual hashing and issue a new SPKI certificate to him. The guest\u27s new certificate chain is stored as an HTTP cookie to enable him to push it to an authorization server at a later time. I also describe how Greenpass can be extended to control access to a virtual private network (VPN) and suggest several interesting future research and development directions that could build on this work

Survey and Evaluation of Advanced Mobility Management Schemes in the Host Identity Layer

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Dynamic deployment of context-aware access control policies for constrained security devices

Securing the access to a server, guaranteeing a certain level of protection over an encrypted communication channel, executing particular counter measures when attacks are detected are examples of security requirements. Such requirements are identi ed based on organizational purposes and expectations in terms of resource access and availability and also on system vulnerabilities and threats. All these requirements belong to the so-called security policy. Deploying the policy means enforcing, i.e., con guring, those security components and mechanisms so that the system behavior be nally the one speci ed by the policy. The deployment issue becomes more di cult as the growing organizational requirements and expectations generally leave behind the integration of new security functionalities in the information system: the information system will not always embed the necessary security functionalities for the proper deployment of contextual security requirements. To overcome this issue, our solution is based on a central entity approach which takes in charge unmanaged contextual requirements and dynamically redeploys the policy when context changes are detected by this central entity. We also present an improvement over the OrBAC (Organization-Based Access Control) model. Up to now, a controller based on a contextual OrBAC policy is passive, in the sense that it assumes policy evaluation triggered by access requests. Therefore, it does not allow reasoning about policy state evolution when actions occur. The modi cations introduced by our work overcome this limitation and provide a proactive version of the model by integrating concepts from action speci cation languages