Betrayal, Distrust, and Rationality: Smart Counter-Collusion Contracts for Verifiable Cloud Computing

Cloud computing has become an irreversible trend. Together comes the pressing need for verifiability, to assure the client the correctness of computation outsourced to the cloud. Existing verifiable computation techniques all have a high overhead, thus if being deployed in the clouds, would render cloud computing more expensive than the on-premises counterpart. To achieve verifiability at a reasonable cost, we leverage game theory and propose a smart contract based solution. In a nutshell, a client lets two clouds compute the same task, and uses smart contracts to stimulate tension, betrayal and distrust between the clouds, so that rational clouds will not collude and cheat. In the absence of collusion, verification of correctness can be done easily by crosschecking the results from the two clouds. We provide a formal analysis of the games induced by the contracts, and prove that the contracts will be effective under certain reasonable assumptions. By resorting to game theory and smart contracts, we are able to avoid heavy cryptographic protocols. The client only needs to pay two clouds to compute in the clear, and a small transaction fee to use the smart contracts. We also conducted a feasibility study that involves implementing the contracts in Solidity and running them on the official Ethereum network.Comment: Published in ACM CCS 2017, this is the full version with all appendice

Public Evidence from Secret Ballots

Elections seem simple---aren't they just counting? But they have a unique, challenging combination of security and privacy requirements. The stakes are high; the context is adversarial; the electorate needs to be convinced that the results are correct; and the secrecy of the ballot must be ensured. And they have practical constraints: time is of the essence, and voting systems need to be affordable and maintainable, and usable by voters, election officials, and pollworkers. It is thus not surprising that voting is a rich research area spanning theory, applied cryptography, practical systems analysis, usable security, and statistics. Election integrity involves two key concepts: convincing evidence that outcomes are correct and privacy, which amounts to convincing assurance that there is no evidence about how any given person voted. These are obviously in tension. We examine how current systems walk this tightrope.Comment: To appear in E-Vote-Id '1

An Evaluation of the New York State Workers’ Compensation Pilot Program for Alternative Dispute Resolution

In 1995, the State 0f New York enacted legislation authorizing the establishment of a workers\u27 compensation alternative dispute resolution pilot program for the unionized sector of the construction industry. Collective bargaining agreements could establish an alternative dispute resolution process for resolving claims (including but not limited to mediation and arbitration), use of an agreed managed care organization or list of authorized providers for medical treatment that constitutes the exclusive source of all medical and related treatment, supplemental benefits, return-to-work programs, and vocational rehabilitation programs. The legislation also directed the School ofIndustrial and Labor Relations at Cornell University (ILR) to evaluate compliance with state and federal due process requirements provided in the collective bargaining agreements authorized by this act, and the use, costs and merits of the alternative dispute resolution system established pursuant to this act. In response to this legislative mandate, ILR reviewed the research previously conducted on alternative dispute resolution (ADR), generally, and in workers\u27 compensation. This included examining the purported advantages and disadvantages of ADR, the prevalence of ADR, and published statistical or anecdotal evidence regarding the impact of ADR. ILR created a research design for claimant-level and project-level analyses, and developed data collection instruments for these analyses that included an injured worker survey for ADR claimants and claimants in the traditional (statutory)workers\u27 compensation system, an Ombudsman\u27s log, a manual of data elements pertaining to ADR and comparison group claimants, and interview questions for ADR signatories and other officials. The findings in this report draw upon a comparison of claimant-level, descriptive statistics (averages) for injured workers in the ADR and traditional (statutory) workers\u27 compensation system; the results of more sophisticated, statistical analyses of claimant-level data; and project-level information (including, but not limited to, interviews with ADR signatories and dispute resolution officials)