Jeffrey K. MacKie-Mason

A Social Mechanism for Supporting Home Computer Security (Download full paper)

Rick Wash and Jeffrey K. MacKie-Mason

Published on: October, 2008

Abstract: Hackers have learned to leverage the enormous number of poorly protected home computers by turning them into a large distributed system (known as a botnet), making home computers an important frontier for security research. They present special problems: owners are unophisticated, and usage profiles are varied making onesize-fits-all firewall policies ineffective. We propose a social firewall that collects security decisions and both user and usage characteristics, and provides users with personalized information to assist with allow/deny recommendations. To succeed, a social firewall must deal with at least three user behavior issues: why contribute private information? why make effort to provide quality information? and, how to prevent manipulation by adversaries? We sketch an incentive-centered design approach to each problem. We provide an economic model and some analytic results for a solution to the fundamental problem: why contribute? We show that an excludable public goods mechanism can achieve a better outcome than a system without social motivators.

Using a Minimum Threshold to Motivate Contributions to Social Computing (Download full paper)

MacKie-Mason, Jeffrey K.

Abstract: Social computing systems collect, aggregate, and share usercontributed content, and therefore depend on contributions from users to function properly. However, humans are intelligent beings and cannot be programmed to behave; system designers must provide incentives to encourage users to contribute. We explore the behavioral consequences of one simple incentive mechanism: require users to contribute a minimum amount of information before they are granted access to the system. Users with a high marginal cost of contribution will stop using the system, but users with a moderate marginal cost will increase their contribution, frequently leading to greater benefits for everyone still using the system. Additionally, if contributions are collaborative and build upon each other, then existing contributors are likely to slightly decrease their contributions, leading to a more ’equal’ distribution of contributions. We show that this mechanism often leads to increased contributions, and provide concrete design advice for using this mechanism in social computing systems.