Local differential privacy in decentralized optimization

Privacy concerns with sensitive data are receiving increasing attention. In this thesis, we study local differential privacy (LDP) in interactive decentralized optimization. Comparing to central differential privacy (DP), where a centralized curator maintains the dataset, LDP is a stronger notion yet with industrial adoption, which allows data of an individual to be privatized before sharing. Consequently, more challenges are encountered to build efficient statistical analyzer in LDP setting. Towards practical decentralized optimization in LDP, we extend LDP into a more comprehensive notion which provides both worst and average case privacy guarantees. Accordingly, two approaches to sharpen utility-privacy tradeoff are proposed for the worst and the average, respectively: First, cryptographically incorporated with merely linear secret sharing, we show the privacy guarantee can be improved by a factor of [square root of] N' where N' amongst all N agents are semi-honest. Second, we take Alternating Direction Method of Multipliers (ADMM), and decentralized (stochastic) gradient descent(D(S)GD) as two concrete examples to propose a framework of first-order based optimization with random local aggregators. We prove such local randomization lead to the same utility guarantee but amplify average LDP by a constant, empirically around 30%. Thorough experiments support our theory.

Name thesis:degree_name

Master

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2019

Author dc:creator

• Xiao, Hanshen.

Advisor dc:contributor.advisor

• Srini Devadas.

• Electrical Engineering and Computer Science.

Statement dc:rights

• MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

https://hdl.handle.net/1721.1/124107

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/124107