Name: Christophe Tartary
Topic: Authentication for Multicast Authentication
Multicast communication enables the distribution of digital content from a single source to a large audience via a public channel such as the Internet. Broadcasting has applications in sensor networks, pay-TV, software updates and military defense systems to name a few. As these applications will distribute private or sensitive information, multicast protocols must provide data origin authentication as well as data confidentiality. In this thesis, we focus our investigations on ensuring authentication of the data source.
Large-scale broadcasts normally do not repeat lost contents since the loss of any piece of data could generate a prohibitive number of redistribution requests at the sender. In addition, the communication channel can be under the control of adversaries performing malicious actions on the data stream. Thus, the security of authentication protocols relies on two aspects: the opponents' computational powers and the network properties. Cryptographic protocols without a security proof cannot be considered as secure in practice as many constructions originally thought secure were successfully broken. Many unconditionally secure schemes were designed. Unfortunately their optimal security is at the cost of a large storage requirement or a one-time use which makes these constructions unsuitable for practical applications. In this work, we assume that the adversaries have polynomially bounded computational powers.
The purpose of this thesis is to design provable secure protocols providing non-repudiation of the origin of a data stream over an unsecured communication channel. We will emphasize that our constructions provide practical solutions to the stream authentication problem, i.e. the requirements of provable security are compatible with the settings of broadcasting.[...]