Cryptology ePrint Archive: Report 2015/489

Scalable and private media consumption with Popcorn

Trinabh Gupta and Natacha Crooks and Srinath Setty and Lorenzo Alvisi and Michael Walfish

Abstract: This paper describes the design, implementation, and experimental evaluation of Popcorn, a media content delivery system that comprehensively hides (even from the content distributor) what is consumed but not necessarily who is doing the consumption. The motivation for Popcorn is both principled and pragmatic: we want to provide provable privacy while still respecting the current commercial context. To instantiate Popcorn, we turn to a powerful primitive from cryptography: private information retrieval (PIR). However, the cost and structure of PIR, as it appears in the literature, present major obstacles to using PIR as the foundation for an Internet-scale service. Nevertheless, with careful system design, and by composing a series of novel refinements and optimizations that leverage the properties of PIR protocols as well as the properties of media streaming, we have produced a system that cheaply hides media consumption, scales to the size of Netflix’s library (8,000 movies) and respects current controls on media dissemination. The per-request cost in Popcorn is less than three times the per-request cost in a baseline system that does not provide privacy.

Category / Keywords: applications / private information retrieval, implementation, cryptographic protocol

Date: received 21 May 2015

Contact author: trinabh at cs utexas edu

Available format(s): PDF | BibTeX Citation

Version: 20150522:064607 (All versions of this report)

Short URL: ia.cr/2015/489

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