A Solution for Wireless Privacy and Payments based on E-cash

The IEEE 802.11 Wireless Local Area Network (WLAN) specifications have been the subject of increased attention due to their rapid commercial adaptation and the introduction of new security and privacy concerns. The IEEE 802.1x standard was introduced in order to overcome the initial security shortcomings of the Wired Equivalent Privacy (WEP) protocol. The IEEE 802.1x standard is an extensible standard that couples 802.11 networks with various authentication services through the incorporation of an Extensible Authentication Protocol (EAP) authentication dialog. The existing implementations of EAP dialogs are based on standard cryptographic solutions for authentication and session key generation but do not, however, provide any form of user anonymity or privacy. Anonymity and privacy are currently of pressing interest, especially in the context of WLANs, which are simultaneously the best medium to provide privacy (there is no physical phone number or connection end-point with a predetermined owner) as well as the most threatening medium to user privacy, as they have the potential of disclosing not only the identity of the user, but also their physical location. At the same time, the potential "perfect hiding" capabilities of WLAN users also highlights the need to control anonymity by introducing more flexible authentication mechanisms. Moreover, payment for wireless services is completely decoupled from the above procedures, raising additional efficiency and privacy concerns. In this work we propose a new EAP authentication dialog based on anonymous electronic cash that provides for privacy, anonymity control, payment acceptance and billing, and authentication. Our solution is based on the notion of "public-key embedding e-cash," an e-cash variant we present and formalize..

Threshold-based intrusion detection in ad hoc networks and secure AODV

Mobile ad hoc networks (MANETs) play an important role in connecting devices in pervasive environments. MANETs provide inexpensive and versatile communication, yet several challenges remain in addressing their security. So far, numerous schemes have been proposed for secure routing and intrusion detection, with only simulations to validate them; little work exists, in implementing such schemes on small handheld devices. In this paper, we present our approach of securing a MANET using a threshold-based intrusion detection system and a secure routing protocol. We present a proof-of-concept implementation of our IDS deployed on handheld devices and in a MANET testbed connected by a secure version of AODV over IPv6 – SecAODV. While the IDS helps detect attacks on data traffic, SecAODV incorporates security features of non-repudiation and authentication, without relying on the availability of a Certificate Authority (CA) or a Key Distribution Center (KDC). We present the design and implementation details of our system, the practical considerations involved, and how these mechanisms can be used to detect and thwart malicious attacks

Detecting and Blocking Unauthorized Access in Wi-Fi Networks

Abstract. Academic and commercial 802.11 hotspots often use an SSLsecured captive portal to authenticate clients. Captive portals provide good usability and interoperability, but poor security. After a captive portal has authenticated a client, session hijacking and freeloading allow attackers to capture or use the client’s session. Freeloading does not require special tools and, surprisingly, is strengthened by the (widely recommended) use of personal firewalls. We propose and evaluate novel defenses against these attacks, session id checking and MAC sequence number tracking, both of which are transparent to clients and do not require changes in client computers. Experiments demonstrate that the proposed defenses are effective against the mentioned attacks and have little overhead.

Recommendations for Mechanical Thrombectomy in Patients with Acute Ischemic Stroke: A Clinical Guide by the Hellenic Stroke Organization

This document presents the consensus recommendations of the Hellenic Stroke Organization which can be of assistance to the treating stroke physicians. © 2017, Springer-Verlag GmbH Germany

Recommendations for Mechanical Thrombectomy in Patients with Acute Ischemic Stroke: A Clinical Guide by the Hellenic Stroke Organization

This document presents the consensus recommendations of the Hellenic Stroke Organization which can be of assistance to the treating stroke physicians. © 2017, Springer-Verlag GmbH Germany