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Sundar, S. Shyam,Bellur, Saraswathi,Oh, Jeeyun,Jia, Haiyan,Kim, Hyang-Sook SAGE Publications 2016 COMMUNICATION RESEARCH - Vol.43 No.5
<P>A critical determinant of message interactivity is the presence of contingency, that is, the messages we receive are contingent upon the messages we send, leading to a threaded loop of interdependent messages. While this “conversational ideal” is easily achieved in face-to-face and computer-mediated communications (CMC), imbuing contingency in human-computer interaction (HCI) is a challenge. We propose two interface features—interaction history and synchronous chat—for increasing perceptions of contingency, and therefore user engagement. We test it with a five-condition, between-participants experiment (<I>N</I> = 110) on a movie search site. Data suggest that interaction history can indeed heighten perceptions of contingency and dialogue, but is perceived as less interactive than chatting. However, the chat function does not appreciably increase perceived contingency or user engagement, both of which are shown to mediate the effects of message interactivity on attitudes toward the site. Theoretical implications for interactivity research and practical implications for interaction design are discussed.</P>
Flexible, Extensible, and Efficient VANET Authentication
Studer, Ahren,Bai, Fan,Bellur, Bhargav,Perrig, Adrian The Korea Institute of Information and Commucation 2009 Journal of communications and networks Vol.11 No.6
Although much research has been conducted in the area of authentication in wireless networks, vehicular ad-hoc networks (VANETs) pose unique challenges, such as real-time constraints, processing limitations, memory constraints, frequently changing senders, requirements for interoperability with existing standards, extensibility and flexibility for future requirements, etc. No currently proposed technique addresses all of the requirements for message and entity authentication in VANETs. After analyzing the requirements for viable VANET message authentication, we propose a modified version of TESLA, TESLA++, which provides the same computationally efficient broadcast authentication as TESLA with reduced memory requirements. To address the range of needs within VANETs we propose a new hybrid authentication mechanism, VANET authentication using signatures and TESLA++ (VAST), that combines the advantages of ECDSA signatures and TESLA++. Elliptic curve digital signature algorithm (ECDSA) signatures provide fast authentication and non-repudiation, but are computationally expensive. TESLA++ prevents memory and computation-based denial of service attacks. We analyze the security of our mechanism and simulate VAST in realistic highway conditions under varying network and vehicular traffic scenarios. Simulation results show that VAST outperforms either signatures or TESLA on its own. Even under heavy loads VAST is able to authenticate 100% of the received messages within 107ms. VANETs use certificates to achieve entity authentication (i.e., validate senders). To reduce certificate bandwidth usage, we use Hu et al.'s strategy of broadcasting certificates at fixed intervals, independent of the arrival of new entities. We propose a new certificate verification strategy that prevents denial of service attacks while requiring zero additional sender overhead. Our analysis shows that these solutions introduce a small delay, but still allow drivers in a worst case scenario over 3 seconds to respond to a dangerous situation.
Flexible, Extensible, and Efficient VANET Authentication
Ahren Studer,Fan Bai,Bhargav Bellur,Adrian Perrig 한국통신학회 2009 Journal of communications and networks Vol.11 No.6
Although much research has been conducted in the area of authentication in wireless networks, vehicular ad-hoc networks (VANETs) pose unique challenges, such as real-time constraints, processing limitations, memory constraints, frequently changing senders, requirements for interoperability with existing standards, extensibility and flexibility for future requirements, etc. No currently proposed technique addresses all of the requirements for message and entity authentication in VANETs. After analyzing the requirements for viable VANET message authentication, we propose a modified version of TESLA, TESLA++, which provides the same computationally efficient broadcast authentication as TESLA with reduced memory requirements. To address the range of needs within VANETs we propose a new hybrid authentication mechanism, VANET authentication using signatures and TESLA++ (VAST), that combines the advantages of ECDSA signatures and TESLA++. Elliptic curve digital signature algorithm (ECDSA) signatures provide fast authentication and non-repudiation, but are computationally expensive. TESLA++ prevents memory and computation-based denial of service attacks. We analyze the security of our mechanism and simulate VAST in realistic highway conditions under varying network and vehicular traffic scenarios. Simulation results show that VAST outperforms either signatures or TESLA on its own. Even under heavy loads VAST is able to authenticate 100% of the received messages within 107ms. VANETs use certificates to achieve entity authentication (i.e., validate senders). To reduce certificate bandwidth usage, we use Hu et al.’s strategy of broadcasting certificates at fixed intervals, independent of the arrival of new entities. We propose a new certificate verification strategy that prevents denial of service attacks while requiring zero additional sender overhead. Our analysis shows that these solutions introduce a small delay, but still allow drivers in a worst case scenario over 3 seconds to respond to a dangerous situation.