Improving the round complexity of VSS in point-topoint networks

We revisit the following question: what is the optimal round complexity of verifiable secret sharing (VSS)? We focus here on the case of perfect VSS where the number of corrupted parties t satisfies t < n/3, with n the total number of parties. Work of Gennaro et al. (STOC 2001) and Fitzi et al. (TCC 2006) shows that, assuming a broadcast channel, 3 rounds are necessary and sufficient for efficient VSS. Existing protocols, however, treat the broadcast channel as being available “for free ” and do not attempt to minimize its usage. This approach leads to relatively poor round complexity when such protocols are compiled to run over a point-to-point network. We show here a VSS protocol that is simultaneously optimal in terms of both the number of rounds and the number of invocations of broadcast. Our protocol also satisfies a certain “2-level sharing ” property that makes it useful for constructing protocols for general secure computation.

AERO|ASTRO Architecture: the hybridizing frontier of emergent industries

Architectural designers often need to strike an uneasy balance between idealism and reality. Under most circumstances, architects are restricted by clients, budgets, and available technologies. However, divorced from traditional constraints, visionary concepts of new dwellings, new cities, and new “worlds” will spark greater forms of innovation and drive creativity for future generations. The exploration of new spatial boundaries and conceptual environments for design will irrevocably alter the human experience while adapting new challenging roles for future architects. Architecture can be understood in part as the art of organizing spaces through the manipulation of materials and forms. Designed spaces are arranged to provide unique sensory reactions for their occupants while emotionally and physically orientating them on Earth. As a catalyst towards the awareness of one’s surroundings, architecture has always had to contend with the many limiting factors imposed by the forces on Earth. These include, but are not limited to, gravity and climate. On Earth, structurally sound construction is limited by the forces of gravity as it influences design capabilities by standardizing forms, functions, and structural elements of architectural spaces. New design challenges and opportunities arrive when we look to create structures outside of Earth’s boundaries. This thesis proposes a futuristic model of an efficient and unique passenger transport system that connects Earth-based hybrid air/space ports with an outer space orbital infrastructural hub. This modern intervention will allow for new outer space industries, such as transit, tourism, and hospitality, which will provide unique opportunities for the future of humanity. Additionally, the thesis studies the positive architectural and experiential potentials for the future living occupancy of outer space. In recognizing the financial and logistical limitations of current space constructions, such as the International Space Station, the thesis looks beyond the limitations of current technologies and towards designs that are driven by the fulfillment of human experiences in space. Life in space, the thesis envisions, will spark new human experiences and rituals while necessitating new forms and designs in architecture. Weightlessness and its related spatial disorientations, in addition to the many other unique conditions in this unfamiliar territory, will inspire a new conceptual language for architecture and human cultures. The thesis will demonstrate that spaces designed for extraterrestrial experiences can be innovatively dynamic as they respond to new cultures and activities that evolve as a reaction to extreme conditions. Introducing humans to the environs of orbital space will be the initial stage in a long-term phasing tactic to colonize and commercialize beyond the expanse of Earth, eventually extending humanity to the remote neighbouring planets of the universe

Ambipolar organic field-effect transistors fabricated using a composite of semiconducting polymer and soluble fullerene

Organic field-effect transistors (FETs) with equivalent hole and electron mobilities have been demonstrated. The devices were fabricated using a phase separated mixture of regioregular poly(3-hexylthiophene) and [6,6]-phenyl C-61-butyric acid methyl ester as the active layer and using aluminum (Al) for the source and drain electrodes. Measurements of the source-drain current versus gate voltage gave an electron mobility of mu(e)=2.0x10(-3) cm(2)/V s and hole mobility of mu(h)=1.7x10(-3)cm(2)/V s. The ambipolar FET properties arise from the use of Al electrodes for the source and drain; the contacts between the Al electrodes and the active layer are improved by thermal annealing at elevated temperatures (150 degrees C), thereby enabling balanced injection for both holes and electrons in a single device.open413

On Constructing Universal One-Way Hash Functions from Arbitrary One-Way Functions

A fundamental result in cryptography is that a digital signature scheme can be constructed from an arbitrary one-way function. A proof of this somewhat surprising statement follows from two results: first, Naor and Yung defined the notion of universal one-way hash functions and showed that the existence of such hash functions implies the existence of secure digital signature schemes. Subsequently, Rompel showed that universal one-way hash functions could be constructed from arbitrary one-way functions. Unfortunately, despite the importance of the result, a complete proof of the latter claim has never been published. In fact, a careful reading of Rompel\u27s original conference publication reveals a number of errors in many of his arguments which have (seemingly) never been addressed. We provide here what is --- as far as we know --- the first complete write-up of Rompel\u27s proof that universal one-way hash functions can be constructed from arbitrary one-way functions

Photovoltaic effects on the organic ambipolar field-effect transistors

An organic multifunctional device, which can function as an ambipolar field-effect transistor (FET) and a photovoltaic (PV) cell, has been demonstrated using a phase separated mixture of poly(3-hexylthiophene) and [6,6]-phenyl C-61-butyric acid methyl ester. The gold (Au) electrode used for hole injection in the FET mode (source) acts as the anode in PV cell mode, and the aluminum (Al) electrode for electron injection in the FET mode (drain) acts as the cathode in PV cell mode. The device exhibits clear PV phenomena under illumination at zero gate bias with a power conversion efficiency of 0.6% as well as the properties of an ambipolar FET when the gate bias is applied.open292

An end-to-end hyperspectral scene simulator with alternate adjacency effect models and its comparison with cameoSim

In this research, we developed a new rendering-based end to end Hyperspectral scene simulator CHIMES (Cranfield Hyperspectral Image Modelling and Evaluation System), which generates nadir images of passively illuminated 3-D outdoor scenes in Visible, Near Infrared (NIR) and Short-Wave Infrared (SWIR) regions, ranging from 360 nm to 2520 nm. MODTRAN TM (MODerate resolution TRANsmission), is used to generate the sky-dome environment map which includes sun and sky radiance along with the polarisation effect of the sky due to Rayleigh scattering. Moreover, we perform path tracing and implement ray interaction with medium and volumetric backscattering at rendering time to model the adjacency effect. We propose two variants of adjacency models, the first one incorporates a single spectral albedo as the averaged background of the scene, this model is called the Background One-Spectra Adjacency Effect Model (BOAEM), which is a CameoSim like model created for performance comparison. The second model calculates background albedo from a pixel’s neighbourhood, whose size depends on the air volume between sensor and target, and differential air density up to sensor altitude. Average background reflectance of all neighbourhood pixel is computed at rendering time for estimating the total upwelled scattered radiance, by volumetric scattering. This model is termed the Texture-Spectra Incorporated Adjacency Effect Model (TIAEM). Moreover, for estimating the underlying atmospheric condition MODTRAN is run with varying aerosol optical thickness and its total ground reflected radiance (TGRR) is compared with TGRR of known in-scene material. The Goodness of fit is evaluated in each iteration, and MODTRAN’s output with the best fit is selected. We perform a tri-modal validation of simulators on a real hyperspectral scene by varying atmospheric condition, terrain surface models and proposed variants of adjacency models. We compared results of our model with Lockheed Martin’s well-established scene simulator CameoSim and acquired Ground Truth (GT) by Hyspex cameras. In clear-sky conditions, both models of CHIMES and CameoSim are in close agreement, however, in searched overcast conditions CHIMES BOAEM is shown to perform better than CameoSim in terms of ℓ1 -norm error of the whole scene with respect to GT. TIAEM produces better radiance shape and covariance of background statistics with respect to Ground Truth (GT), which is key to good target detection performance. We also report that the results of CameoSim have a many-fold higher error for the same scene when the flat surface terrain is replaced with a Digital Elevation Model (DEM) based rugged one

Multilayer bipolar field-effect transistors

Field-effect transistors comprising a layer of regioregular poly(3-hexylthiophene) (rr-P3HT) separated from a parallel layer of the soluble fullerene,[6,6]-phenyl C-61-butyric acid methyl ester (PCBM) by a layer of titanium suboxide (TiOx), are fabricated by solution processing. Because the TiOx is an electron transporting material and a hole blocking material, this multilayer architecture operates either in the p-channel mode with holes in the rr-P3HT layer or in the n-channel mode with electrons in the PCBM layer.open201

Improving the Round Complexity of VSS in Point-to-Point Networks

We revisit the following question: what is the optimal round complexity of verifiable secret sharing~(VSS)? We focus here on the case of perfectly-secure VSS where the number of corrupted parties~$t$ satisfies $t < n/3$, with $n$ being the total number of parties. Work of Gennaro et al. (STOC~2001) and Fitzi et al. (TCC~2006) shows that, assuming a broadcast channel, 3~rounds are necessary and sufficient for efficient VSS. The efficient 3-round protocol of Fitzi et al., however, treats the broadcast channel as being available ``for free\u27\u27 and does not attempt to minimize its usage. This approach leads to relatively poor round complexity when protocols are compiled for a point-to-point network. We show here a VSS protocol that is simultaneously optimal in terms of both the number of rounds and the number of invocations of broadcast. Our protocol also has a certain ``2-level sharing\u27\u27 property that makes it useful for constructing protocols for general secure computation