Reuse It Or Lose It: More Efficient Secure Computation Through Reuse of Encrypted Values

Two-party secure function evaluation (SFE) has become significantly more feasible, even on resource-constrained devices, because of advances in server-aided computation systems. However, there are still bottlenecks, particularly in the input validation stage of a computation. Moreover, SFE research has not yet devoted sufficient attention to the important problem of retaining state after a computation has been performed so that expensive processing does not have to be repeated if a similar computation is done again. This paper presents PartialGC, an SFE system that allows the reuse of encrypted values generated during a garbled-circuit computation. We show that using PartialGC can reduce computation time by as much as 96% and bandwidth by as much as 98% in comparison with previous outsourcing schemes for secure computation. We demonstrate the feasibility of our approach with two sets of experiments, one in which the garbled circuit is evaluated on a mobile device and one in which it is evaluated on a server. We also use PartialGC to build a privacy-preserving "friend finder" application for Android. The reuse of previous inputs to allow stateful evaluation represents a new way of looking at SFE and further reduces computational barriers.Comment: 20 pages, shorter conference version published in Proceedings of the 2014 ACM SIGSAC Conference on Computer and Communications Security, Pages 582-596, ACM New York, NY, US

A Brief Review of Research on Forms of Instruction

In colleges of education, there is very strong support for minimally-guided instruction. This form of teaching is based around being a “guide on the side” as opposed to a “sage on the stage” – in other words, direct instruction of one’s students is seen as ineffective or even harmful, whereas instructional approaches based on encouraging students to teach themselves and construct their own knowledge with the teacher acting solely as a “facilitator” is seen as best practice. Despite the prevalence of this viewpoint amongst most education professors, there is very little evidence for its effectiveness. In fact, minimally-guided instruction can be quite harmful – it tends to widen the achievement gap between white students and students of color, and between high-income students and low-income students. It also leads to lower overall academic achievement and life success when compared with the results of directly instructing one’s students. This project summarizes the extensive research literature from the past several decades regarding which teaching strategies are most and least effective

The Strategic Disclosure of Currency Headwinds and Tailwinds

In this study, I examine whether companies are more likely to disclose revenue growth adjusted to remove the effects of foreign currency fluctuations (constant-currency revenue growth rates) when currency fluctuations decrease revenue growth (i.e., there is a currency headwind) than when currency fluctuations increase revenue growth. Public companies increasingly cite non-GAAP performance metrics when announcing earnings. While regulators see value in non-GAAP reporting, they continue to express concern that it is carried out inconsistently and in a misleading manner. Because the disclosure of constant-currency revenue growth is discretionary, companies have an incentive to strategically disclose it only when it benefits them to do so. I first create a novel proxy for the exchange rate impact on revenue and hand collect data on whether or not companies provide constant-currency revenue growth disclosures in earnings announcements. I find that when a company has a currency headwind, it is 146 percent more likely to disclose constant-currency growth rates. In addition, I examine aspects of the information environment and find some evidence suggesting that the effect decreases when information asymmetry is low

A field evaluation of dust palliatives in West Virginia

It is estimated that a vehicle making a single pass on one mile of untreated, unpaved road every day can generate one ton of dust per year. This dust constitutes fine materials which act as a binder to the larger coarse aggregates within surface gravel. As these fines are removed, the surface deteriorates and expensive aggregate ends up along the roadside in ditches and culverts. The surface continually deteriorates until the road must be reconstructed. Furthermore, airborne dust presents serious safety concerns to traveling motorists and health concerns associated with respiratory illnesses. At the West Virginia Division of Highway\u27s current funding levels it is anticipated that less hot-mix asphalt will be used to pave roadways for the purpose of dust control. If the road is treated with a chemical dust suppressant, however, it can retain a percentage of fines that would otherwise be expelled as dust.;The purpose of this thesis was to evaluate the effectiveness of five commercially available chemical dust palliatives for use on public gravel secondary roads in West Virginia. Dust control products included in this study are a petroleum emulsion with polymer, synthetic organic fluid, calcium chloride, bituminous resin pitch, and lignin sulfonate. Three methods of field testing were used which included a mobile dust sampling device, soil silt fractions, and moisture analyses. Results of field testing indicated that calcium chloride was the most cost-effective material for providing dust control throughout the evaluation period. All but one product provided some measurable degree of dust control at the end of the three-month evaluation period when compared to the four untreated control sections

How to make better mistakes in public policy

We all make mistakes, a tendency which also extends to those who work in public policy. Despite this seemingly universal tendency, we often only hear about successes. Bucking this trend, Kevin Arceneaux and Daniel Butler describe a recent pilot program aimed at boosting civic engagement in a Midwestern town, based on Get Out the Vote literature. Rather than increasing the number of people who volunteered for town committees as intended, the three tactics they tested actually had no effect or reduced the chances that people would volunteer

Continuous Improvements to East Coast Abort Landings for Space Shuttle Aborts

Improvement initiatives in the areas of guidance, flight control, and mission operations provide increased capability for successful East Coast Abort Landings (ECAL). Automating manual crew procedures in the Space Shuttle's onboard guidance allows faster and more precise commanding of flight control parameters needed for successful ECALs. Automation also provides additional capability in areas not possible with manual control. Operational changes in the mission concept allow for the addition of new landing sites and different ascent trajectories that increase the regions of a successful landing. The larger regions of ECAL capability increase the safety of the crew and Orbiter