Applications of Broadcast Encryption Schemes and Related Technical Mechanisms for Digital Rights Management of Multimedia Broadcasts

Solutions to the problem of transmitting data to a group of receivers in a way that only the correct sub-set of all possible receivers can decrypt the data are needed by a number of applications: Pay-TV, rights-controlled media, audio streaming, realtime business data, multicast communication are current examples, but there also off-line applications, particularly with regard to storage media for multimedia content (e. g., CD, DVD). The well-established cryptographic solution to the problem is called Broadcast Encryption and this term was first coined by Fiat and Naor in 1993. In the context of Pay-TV that had become a successful commercial model in the 1980ies a technological approach to the problem was developed and data formats were standardized. The known technical solutions use cryptographic mechanisms but do not apply a fully-fledged broadcast encryption scheme. The umbrella term referring to technologies in this area is Conditional Access Systems (CAS). The more general term Digital Rights Management (DRM) refers to all technological measures that enforce the rights and restrictions on digital content as defined by the content owners (e. g., copy or content protection, usage rights). Broadcast Encryption is the cryptographic tool regarding DRM for stateless receivers of unidirectional communication. In this dissertation we focus on the problem how valuable digital multimedia content can be delivered by a global service while enforcing the digital rights as defined