SPORC: Group collaboration using untrusted cloud resources

Ariel J. Feldman, William P. Zeller, Michael J. Freedman, Edward W. Felten

Research output: Chapter in Book/Report/Conference proceedingConference contribution

34 Scopus citations

Abstract

Cloud-based services are an attractive deployment model for user-facing applications like word processing and calendaring. Unlike desktop applications, cloud services allow multiple users to edit shared state concurrently and in real-time, while being scalable, highly available, and globally accessible. Unfortunately, these benefits come at the cost of fully trusting cloud providers with potentially sensitive and important data. To overcome this strict tradeoff, we present SPORC, a generic framework for building a wide variety of collaborative applications with untrusted servers. In SPORC, a server observes only encrypted data and cannot deviate from correct execution without being detected. SPORC allows concurrent, low-latency editing of shared state, permits disconnected operation, and supports dynamic access control even in the presence of concurrency. We demonstrate SPORC's flexibility through two prototype applications: a causally-consistent key-value store and a browser-based collaborative text editor. Conceptually, SPORC illustrates the complementary benefits of operational transformation (OT) and fork* consistency. The former allows SPORC clients to execute concurrent operations without locking and to resolve any resulting conflicts automatically. The latter prevents a misbehaving server from equivocating about the order of operations unless it is willing to fork clients into disjoint sets. Notably, unlike previous systems, SPORC can automatically recover from such malicious forks by leveraging OT's conflict resolution mechanism.

Original languageEnglish (US)
Title of host publicationProceedings of the 9th USENIX Symposium on Operating Systems Design and Implementation, OSDI 2010
PublisherUSENIX Association
Pages337-350
Number of pages14
ISBN (Electronic)9781931971799
StatePublished - 2019
Event9th USENIX Symposium on Operating Systems Design and Implementation, OSDI 2010 - Vancouver, Canada
Duration: Oct 4 2010Oct 6 2010

Publication series

NameProceedings of the 9th USENIX Symposium on Operating Systems Design and Implementation, OSDI 2010

Conference

Conference9th USENIX Symposium on Operating Systems Design and Implementation, OSDI 2010
CountryCanada
CityVancouver
Period10/4/1010/6/10

All Science Journal Classification (ASJC) codes

  • Information Systems
  • Computer Networks and Communications
  • Hardware and Architecture

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