05/2014

VOL. 57 NO. 05

Practice

Contributed Articles

Review Articles

52

44 The NSA and Snowden:

Securing the All-Seeing Eye How good security at the NSA could have stopped him.

By Bob Toxen

52 A Primer on Provenance

Better understanding data requires tracking its history and context.

By Lucian Carata, Sherif Akoush, Nikilesh Balakrishnan,

Thomas Bytheway, Ripduman Sohan, Margo Seltzer, and Andy Hopper

61 Don’t Settle for Eventual Consistency Stronger properties for low-latency geo-replicated storage.

By Wyatt Lloyd, Michael J. Freedman, Michael Kaminsky, and David G. Andersen

IMAGES BY ANDRIJ BORYS ASSOCIATES; ILLUS TRATION BY EUGENE KOSTSOV

Articles’ development led by queue.acm.org

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98

70 Cloud Security: A Gathering Storm Users’ trust in cloud systems is undermined by the lack of transparency in existing security policies.

By Mihir Nanavati, Patrick Colp, Bill Aiello, and Andrew Warfield

80 Reducing the Software Value Gap How to cope with the growing demand for software solutions at no extra cost.

By Shimeon Pass and Boaz Ronen

88 The Community Source Approach to Software Development and the Kuali Experience Participating educational institutions get a much more cost-effective result compared to the commercial off-the-shelf alternative. By Manlu Liu, Sean Hansen, and Qiang Tu

98 Understanding the Empirical Hardness of NP-Complete Problems Using machine learning to predict algorithm runtime.

By Kevin Leyton-Brown, Holger H. Hoos, Frank Hutter, and Lin Xu

Research Highlights

109 Technical Perspective

The Interplay of Neuroscience and Cryptography

By Ari Juels and Bonnie Wong

110 Neuroscience Meets Cryptography: Crypto Primitives Secure

Against Rubber Hose Attacks

By Hristo Bojinov, Daniel Sanchez, Paul Reber, Dan Boneh, and Patrick Lincoln

About the Cover:

Much has been written about Edward Snowden, the former National Security Agency subcontractor who shot to global notoriety by leaking top-secret data about the agency’s surveillance activities. While media outlets continue to debate why he did it, this month’s cover story (p. 44) traces how he did it, pointing out the glaring weaknesses in

the NSA’s own security practices. Cover illustration by Peter Crowther Associates.