Public-key traitor tracing schemes allow for a multitude of non-trusted content providers using the same set of keys, which makes the scheme ``server-side scalable.'' To make such schemes also ``client-side scalable,'' i.e. long lived and usable for a large population of subscribers that changes dynamically over time, it is crucial to implement efficient Add-user and Remove-user operations. Previous work on public-key traitor tracing did not address this dynamic scenario thoroughly, and there is no efficient scalable public key traitor tracing scheme that allows an increasing number of Add-user and Remove-user operations.
To address these issues, we introduce the model of Scalable Public-Key Traitor Tracing, and present the first construction of such a scheme. Our model mandates for deterministic traitor tracing and an unlimited number of efficient Add-user operations and Remove-user operations. A scalable system achieves an unlimited number of revocations while retaining high level of efficiency by dividing the run-time of the system into periods. Each period has a saturation level for the number of revocations. When a period becomes saturated, an _efficient_ New-period operation is issued by the system server that resets the saturation level. We present a formal adversarial model for our system taking into account its periodic structure, and we prove our construction secure, both against adversaries that attempt to cheat the revocation mechanism as well as against adversaries that attempt to cheat the traitor tracing mechanism.
Category / Keywords: cryptographic protocols / Digital Content Distribution, Traitor Tracing, Scalability, Broadcast Encryption, Multicast Publication Info: Extended abstract of this work appears in proceeding of PODC 2004 Date: received 8 Jul 2004, last revised 10 Jul 2004 Contact author: fazio at cs nyu edu Available formats: Postscript (PS) | Compressed Postscript (PS.GZ) | PDF | BibTeX Citation Note: The present version corrects a flaw in the main scheme proposed in the extended abstract. Also, the presentation has been improved, and it now includes a detailed security analysis and proofs of all lemmata. Version: 20040710:114647 (All versions of this report) Discussion forum: Show discussion | Start new discussion