Encryption of Composite Multimedia Contents for Access Control

Masaaki FUJIYOSHI  Shoko IMAIZUMI  Hitoshi KIYA  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E90-A    No.3    pp.590-596
Publication Date: 2007/03/01
Online ISSN: 1745-1337
DOI: 10.1093/ietfec/e90-a.3.590
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Multimedia and Mobile Signal Processing)
Category: Image
multimedia communication,  access control,  cryptography,  image coding,  Internet,  

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An encryption scheme is proposed that considers hierarchies in media, such as text, images, sound, and so on, in a composite multimedia content to enable versatile access control. In the proposed scheme, a content provider has only one managed key (the master key) for a particular composite multimedia content, and an user who is permitted to access a reserved content entities in the composite content receives only one key that is subordinately generated from the master key. Another key generated from the identical master key is delivered to another user, and this permits the user to access different entities. This scheme introduces a new key concept, namely "unusable key," to keep all entities encrypted in a particular medium and to simultaneously decrypt several entities in other media. The other new key, "numbering key," is also used in this scheme to support simultaneous partial decryption of multiple images that are coded with a scalable coding technology. Simulation results show the effectiveness of the proposed scheme; in particular, the length of the managed master key and that of keys to be delivered to users are small.