@phdthesis{Liu2006, author = {Liu, Fuwen}, title = {A security architecture for a peer-to-peer video conference system}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus-445}, school = {BTU Cottbus - Senftenberg}, year = {2006}, abstract = {More and more modern group oriented collaborative applications use the peer-to-peer (P2P) paradigm to be independent of expensive infrastructures as they are, for instance, provided for audio and video conferences by H.323 systems. Decentralized P2P systems better support spontaneity and mobility to set up meetings at varying locations or in ad hoc environments. This is especially advantageous for business communication over the Internet but also for other collaborative applications such as audio/video conferences. Decentralized collaborative P2P solutions require appropriate mechanisms to protect group privacy and data integrity. The broadly available security infrastructures, like virtual private networks (VPN) in the link, network, and transport layer, do not well fulfill the requirements regarding security, efficiency, and flexibility raised by a conferencing system. A dedicated security architecture in the application layer is, therefore, highly desired for protecting a P2P video conference. A centralized client/server based video conference system can be well shielded in a standard manner, whilst there exist no off-the-shelf approaches to specifying how to secure a P2P video conference up to now. This Ph.D. thesis addresses this urgent issue by presenting an effective and flexible security architecture and showing how it can be embedded into a P2P video conferencing system using the BRAVIS system as example. The cornerstone of the security architecture is the decentralized group key management. For this purpose, a new distributed key exchange protocol has been proposed. It is especially well suited for applications in real-time P2P settings for its higher efficiency than existing ones concerning the group key renewal delay. Furthermore, a novel video encryption algorithm has been developed to meet the strict real-time constraints required in a video conference. Its outstanding features include a good balance between security and efficiency, no impairment on video compression efficiency, and readily integration into the existing multimedia systems. These make it more practicable to encrypt video data than existing approaches.}, subject = {Peer-to-Peer-Netz; Videokonferenz; Computersicherheit; Sicherheitsarchitektur; Peer-to-Peer; Videokonferenz; Gruppenschl{\"u}sselverwaltung; Videoverschl{\"u}sselung; Security architecture; Peer-to-Peer; Video conference; Group key management; Video encryption}, language = {en} } @phdthesis{Zuehlke2004, author = {Z{\"u}hlke, Mario}, title = {Verteilt organisierte Mehrteilnehmer-Videokonferenzen f{\"u}r geschlossene Gruppen im Internet}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-000000540}, school = {BTU Cottbus - Senftenberg}, year = {2004}, abstract = {Videokonferenzen gelten als eine popul{\"a}re Anwendung in modernen Netzwerken. Trotz langj{\"a}hriger Erfahrungen geh{\"o}ren sie nicht zu den allt{\"a}glich genutzten Diensten. Videokonferenzdienste im Internet unterst{\"u}tzen meist offene Konferenzgruppen. Jedoch haben die Mehrzahl der allt{\"a}glichen Beratungen einen geschlossenen Charakter. Systeme, die geschlossene Gruppen unterst{\"u}tzen, basieren meist auf spezieller Studiotechnik. Desktop-Systeme lassen nur ein begrenztes Leistungsangebot zu. Besonders beim Aufbau von Mehrteilnehmer-Gruppen ist es schwierig, eine gute Dienstg{\"u}te bereitzustellen. Deshalb haben Systeme f{\"u}r geschlossene Gruppen bisher keine breite Anwendung gefunden. Die vorliegende Arbeit untersucht zwei An{\"a}tze zur Gestaltungsprinzipien von geschlossenen Mehrteilnehmer-Videokonferenzsystemen. Der Erste untersucht den Aufbau von globalen Konferenzen {\"u}ber den Verbund lokaler Systeme. Der Zweite, ein Peer-to-Peer-Konzept, untersucht die Unterst{\"u}tzung von geschlossenen Gruppen im Internet.}, subject = {Videokonferenz; IP; Teilnehmerrechensystem; Unicastingverfahren; {\"U}berlastkontrolle; Dienstg{\"u}te; Peer-to-Peer-Netz; Mehrteilnehmer-Videokonferenz; QoS; Peer-to-Peer; Gruppenkommunikation; Geschlossen Gruppe}, language = {de} }