This paper introduces a SNARK called Brakedown. Brakedown targets R1CS, a popular NP-complete problem that generalizes circuit-satisfiability. It is the first built system that provides a linear-time prover, meaning the prover incurs O(N) finite field operations to prove the satisfiability of an N-sized R1CS instance. Brakedown ’s prover is faster, both concretely and asymptotically, than prior SNARK implementations. It does not require a trusted setup and may be post-quantum secure. Furthermore, it is compatible with arbitrary finite fields of sufficient size; this property is new among built proof systems with sublinear proof sizes. To design Brakedown, we observe that recent work of Bootle, Chiesa, and Groth (BCG, TCC 2020) provides a polynomial commitment scheme that, when combined with the linear-time interactive proof system of Spartan (CRYPTO 2020), yields linear-time IOPs and SNARKs for R1CS (a similar theoretical result was previously established by BCG, but our approach is conceptually simpler, and crucial for achieving high-speed SNARKs). A core ingredient in the polynomial commitment scheme that we distill from BCG is a linear-time encodable code. Existing constructions of such codes are believed to be impractical. Nonetheless, we design and engineer a new one that is practical in our context. We also implement a variant of Brakedown that uses Reed-Solomon codes instead of our linear-time encodable codes; we refer to this variant as Shockwave. Shockwave is not a linear-time SNARK, but it provides shorter proofs and lower verification times than Brakedown, and also provides a faster prover than prior plausibly post-quantum SNARKs.

We develop a method to incorporate model uncertainty by model averaging in generalized linear models subject to multiple endogeneity and instrumentation. Our approach builds on a Gibbs sampler for the instrumental variable framework that incorporates model uncertainty in both outcome and instrumentation stages. Direct evaluation of model probabilities is intractable in this setting. However, we show that by nesting model moves inside the Gibbs sampler, a model comparison can be performed via conditional Bayes factors, leading to straightforward calculations. This new Gibbs sampler is slightly more involved than the original algorithm and exhibits no evidence of mixing difficulties. We further show how the same principle may be employed to evaluate the validity of instrumentation choices. We conclude with an empirical marketing study: estimating opening box office by three endogenous regressors (prerelease advertising, opening screens, and production budget).

This paper introduces Brakedown, the first built system that provides linear-time SNARKs for NP, meaning the prover incurs O(N) finite field operations to prove the satisfiability of an N -sized R1CS instance. Brakedown’s prover is faster, both concretely and asymptotically, than prior SNARK implementations. Brakedown does not require a trusted setup and is plausibly post-quantum secure. Furthermore, it is compatible with arbitrary finite fields of sufficient size; this property is new amongst implemented arguments with sublinear proof sizes. To design Brakedown, we observe that recent work of Bootle, Chiesa, and Groth (BCG, TCC 2020) provides a polynomial commitment scheme that, when combined with the linear-time interactive proof system of Spartan (CRYPTO 2020), yields linear-time IOPs and SNARKs for R1CS (a similar theoretical result was previously established by BCG, but our approach is conceptually simpler, and crucial for achieving high-speed SNARKs). A core ingredient in the polynomial commitment scheme that we distill from BCG is a linear-time encodable code. Existing constructions of such codes are believed to be impractical. Nonetheless, we design and engineer a new one that is practical in our context. We also implement a variant of Brakedown that uses Reed-Solomon codes instead of our linear-time encodable codes; we refer to this variant as Shockwave. Shockwave is not a linear-time SNARK, but it provides shorter proofs and lower verification times than Brakedown (it also provides a faster prover than prior plausibly post-quantum SNARKs). As a modest additional contribution, we observe that one can render the aforementioned SNARK zero knowledge and reduce the proof size and verifier time from O( √ N) to polylog(N)—while maintaining a linear-time prover—by outsourcing the verifier’s work via one layer of proof composition with an existing zkSNARK as the “outer” proof system. ∗This manuscript is an update to [LSTW21]. It contains substantial new results and updated presentation, including the design and implementation of a concretely efficient error-correcting code with linear-time encoding, and associated SNARK. 1In the Transformers universe, Brakedown and Shockwave are powerful (and fast) Decepticons.

This paper studies zero-knowledge SNARKs for NP, where the prover incurs O(N) finite field operations to prove the satisfiability of an N -sized R1CS instance. We observe that recent work of Bootle, Chiesa, and Groth (BCG, TCC 20) provides a polynomial commitment scheme that, when combined with the linear-time interactive proof system of Spartan (CRYPTO 20), yields linear-time IOPs and SNARKs for R1CS. Specifically, for security parameter λ, and for an N -sized R1CS instance over a field of size exp(λ) and fixed > 0, the prover incurs O(N) finite field operations to produce a proof of size Oλ(N ) that can be verified in Oλ(N )—after a one-time preprocessing step, which requires O(N) finite field operations. This reestablishes the main result of BCG. Arguably, our approach is conceptually simpler and more direct. Additionally, the polynomial commitment scheme that we distill from BCG is of independent interest; it improves over the prior state of the art by offering the first scheme where the time to commit to an N -sized polynomial is O(N) finite field operations. We further observe that one can render the aforementioned SNARK zero knowledge and reduce the proof size and verifier time to polylogarithmic—while maintaining a linear-time prover—by outsourcing the verifier’s work via one layer of proof composition with an existing zkSNARK as the “outer” proof system. A similar result can be derived from recent work of Bootle, Chiesa, and Liu (ePrint 2020/1527). We implement the aforementioned polynomial commitment scheme with = 1/2 and combine it with Spartan’s interactive proof system to obtain a SNARK for R1CS. We refer to this combination as Cerberus. It uses Reed-Solomon codes in the polynomial commitment scheme, and hence the prover is not asymptotically linear-time. Nonetheless, Cerberus features the fastest known prover (the only exception is Spartan when proving large instances over 256-bit fields), and is plausibly post-quantum secure.

This paper studies zero-knowledge SNARKs for NP, where the prover incurs O ( N ) finite field operations to prove the satisfiability of an N -sized R1CS instance. We observe that recent work of Bootle, Chiesa, and Groth (BCG, TCC 20) provides a polynomial commitment scheme that, when combined with the linear-time interactive proof system of Spartan (CRYPTO 20), yields linear-time SNARKs for R1CS. Specifically, for security parameter λ , and for an N -sized R1CS instance over a field of size exp( λ ) and fixed (cid:15) > 0, the prover incurs O ( N ) finite field operations to produce a proof of size O λ ( N (cid:15) ) that can be verified in O λ ( N (cid:15) )—after a one-time preprocessing step, which requires O ( N ) finite field operations. This reestablishes the main result of BCG. Arguably, our approach is conceptually simpler and more direct. Additionally, the polynomial commitment scheme that we distill from BCG is of independent interest; it improves over the prior state of the art by offering the first scheme where the time to commit and to prove an evaluation of a committed polynomial are both O ( N ) finite field operations for an N -sized polynomial. We further observe that one can render the aforementioned SNARK zero knowledge and reduce the proof size and verifier time to polylogarithmic—while maintaining a linear-time prover—by outsourcing the verifier’s work via one layer of proof composition with an existing zkSNARK as the “outer” proof system. A similar result was recently obtained by Bootle, Chiesa, and Liu (ePrint 2020/1527).

We report results of investigation of the phonon and thermal properties of the exfoliated films of layered single crystals of antiferromagnetic FePS3 and MnPS3 semiconductors. Raman spectroscopy was conducted using three different excitation lasers with wavelengths of 325 nm (UV), 488 nm (blue), and 633 nm (red). UV-Raman spectroscopy reveals spectral features which are not detectable via visible Raman light scattering. The thermal conductivity of FePS3 and MnPS3 thin films was measured by two different techniques: the steady-state Raman optothermal and transient time-resolved magneto-optical Kerr effect. The Raman optothermal measurements provided the orientation-average thermal conductivity of FePS3 to be 1.35 ± 0.32 W m-1 K-1 at room temperature. The transient measurements revealed that the through-plane and in-plane thermal conductivity of FePS3 are 0.85 ± 0.15 and 2.7 ± 0.3 W m-1 K-1, respectively. The films of MnPS3 have higher thermal conductivity of 1.1 ± 0.2 W m-1 K-1 through-plane and 6.3 ± 1.7 W m-1 K-1 in-plane. The data obtained by the two techniques are in agreement and reveal strong thermal anisotropy of the films and the dominance of phonon contribution to heat conduction. The obtained results are important for the interpretation of electric switching experiments with antiferromagnetic materials as well as for the proposed applications of the antiferromagnetic semiconductors in spintronic devices.

We introduce Xiphos and Kopis, new transparent zero-knowledge succinct non-interactive arguments of knowledge (zkSNARKs) for R1CS. They do not require a trusted setup, and their security relies on the standard SXDH problem. They achieve non-interactivity in the random oracle model using the Fiat-Shamir transform. Unlike prior transparent zkSNARKs, which support either a fast prover, short proofs, or quick verification, our work is the first to simultaneously achieve all three properties (both asymptotically and concretely) and in addition an inexpensive setup phase, thereby providing the first quadruple-efficient transparent zkSNARKs (Quarks). Under both schemes, for an R1CS instance of size n and security parameter $\\lambda$, the prover incurs $Oλ(n)\"\u003eO_{\\lambda}(n)$ costs to produce a proof of size $Oλ(n)\"\u003eO_{\\lambda}(\\log{n})$. In Xiphos, verification time is $Oλ(n)\"\u003eO_{\\lambda}(\\log{n})$, and in Kopis it is $Oλ(n)\"\u003eO_{\\lambda}(\\sqrt{n})$. In terms of concrete efficiency, compared to prior state-of-the-art transparent zkSNARKs, Xiphos offers the fastest verification; its proof sizes are competitive with those of SuperSonic [EUROCRYPT 2020], a prior transparent SNARK with the shortest proofs in the literature. Xiphos’s prover is fast: its prover is $\\approx3.85×\"\u003e\\times$ of Spartan [CRYPTO 2020], a prior transparent zkSNARK with the fastest prover in the literature, and is $250\"\u003e 376\\times$ faster than SuperSonic. Kopis, at the cost of increased verification time (which is still concretely faster than SuperSonic), shortens Xiphos’s proof sizes further, thereby producing proofs shorter than SuperSonic. Xiphos and Kopis incur $10\"\u003e10$–$10,000×\"\u003e10,000\\times$ lower preprocessing costs for the verifier in the setup phase depending on the baseline. Finally, a byproduct of Kopis is Lakonia, a NIZK for R1CS with $Oλ(n)\"\u003eO_{\\lambda}(\\log{n})$-sized proofs, which provides an alternative to Bulletproofs [S\u0026P 2018] with over an order of magnitude faster proving and verification times.

This article describes recent progress in realizing verifiable state machines, a primitive that enables untrusted services to provide cryptographic proofs that they operate correctly. Applications of this primitive range from proving the correct operation of distributed and concurrent cloud services to reducing blockchain transaction costs by leveraging inexpensive off-chain computation without trust.

This article describes recent progress in realizing verifiable state machines, a primitive that enables untrusted services to provide cryptographic proofs that they operate correctly. Applications of this primitive range from proving the correct operation of distributed and concurrent cloud services to reducing blockchain transaction costs by leveraging inexpensive off-chain computation without trust.

We describe an optical pump/probe system for sensitive measurements of time-resolved optical measurements of material dynamics. The instrument design is optimized for time-resolved magneto-optic Kerr effect (TR-MOKE) measurements of dynamics in magnetic materials. The system also allows for time-domain thermoreflectance (TDTR) measurements of thermal transport properties and picosecond acoustic measurements of film thickness and/or elastic constants. The system has several advantages over the conventional designs for TR-MOKE and/or TDTR systems. Measurements of pump-induced changes to the probe beam intensity are shot-noise limited. The system's design allows for MOKE and/or thermoreflectance measurements of both sides of a sample. Pumping and probing the sample on opposite sides allows nanoscale flash diffusivity measurements of transport properties. The wavelengths of the pump and probe beams are straightforward to tune between 350-525 nm and 690-1050 nm. A tunable wavelength allows for optical resonances in a wide array of materials to be excited and/or probed. Finally, the setup is calibrated to allow for the real and imaginary components of Kerr signals to be separately quantified.

Journal Article Improved Microanalysis Using Cathodoluminescence Spectrum Imaging with Higher Spatial Sampling Get access David Stowe, David Stowe Gatan, Inc., Pleasanton, California, United States Search for other works by this author on: Oxford Academic Google Scholar Jonathan Lee, Jonathan Lee Gatan, Inc., Pleasanton, California, United States Search for other works by this author on: Oxford Academic Google Scholar Michael Bertilson, Michael Bertilson Gatan, Inc., Pleasanton, California, United States Search for other works by this author on: Oxford Academic Google Scholar Salvatore Fahey, Salvatore Fahey Gatan, Inc., Pleasanton, California, United States Search for other works by this author on: Oxford Academic Google Scholar John Hunt John Hunt Gatan, Inc., Pleasanton, California, United States Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 26, Issue S2, 1 August 2020, Pages 2698–2699, https://doi.org/10.1017/S1431927620022461 Published: 01 August 2020

To discuss current concussion management guidelines in Adaptive Sports and educate clinicians on our Concussion Management Protocol (CMP).

This paper introduces a new approach to reduce end-to-end costs in large-scale replicated systems built under a Byzantine fault model. Specifically, our approach transforms a given replicated state machine (RSM) to another RSM where nodes incur lower costs by delegating state machine execution: an untrusted prover produces succinct cryptographic proofs of correct state transitions along with state changes, which nodes in the transformed RSM verify and apply respectively.To realize our approach, we build Piperine, a system that makes the proof machinery profitable in the context of RSMs. Specifically, Piperine reduces the costs of both proving and verifying the correctness of state machine execution while retaining liveness-a distinctive requirement in the context of RSMs. Our experimental evaluation demonstrates that, for a payment service, employing Piperine is more profitable than naive reexecution of transactions as long as there are > 10 4 nodes. When we apply Piperine to ERC-20 transactions in Ethereum (a real-world RSM with up to 10 5 nodes), it reduces per-transaction costs by 5.4× and network costs by 2.7×.

SESSION TITLE: Tuesday Abstract Posters SESSION TYPE: Original Investigation Posters PRESENTED ON: 10/22/2019 01:00 PM - 02:00 PM PURPOSE: Chest pain accounts for greater than 6 million annual visits to the hospital. The rate of ischemic heart disease in Robeson County, NC was 34-36% greater than the state itself and 25-31% greater than the national rate. Given the extensive prevalence of chest pain, our goal was to identify whether or not patients were undergoing undergo adequate risk stratification and consequently proper medical intervention. We hypothesized that current American College of Cardiology/American Heart Association guidelines regarding timing of noninvasive cardiac testing were not being met. More specifically, that low-risk patients were being inappropriately tested and that moderate-to-high risk patients were not receiving appropriate testing prior to discharge or within 72 hours of discharge. METHODS: We performed a randomized retrospective chart review on 146 patients who presented with symptoms of acute coronary syndrome from the months of 5/1/2018 to 10/30/2018 using the HEART score to triage them into low-risk and moderate-to-high-risk categories. Further analysis was done to categorize patients according to gender, ethnicity, and insurance type. Finally, a cost analysis was performed to estimate the cost of inappropriately performed cardiac testing. RESULTS: We found that the general adherence rate to guideline-directed noninvasive cardiac testing was 65%, for low-risk patients was 40%, and for moderate-high risk patients was 71%. Other adherence rates were as follows: 64% for females, 68% for males, 71% for Caucasians, 64% for Blacks, 63% for American Indians, 57% for Medicare patients, 76% for Medicaid patients, and 71% for patients with commercial insurance. Using standardized price ranges for the various stress tests, we estimated that the cost of inappropriately low-risk patients ranged from $8,000 – 80,000. Moreover, we estimated the cost of appropriately testing moderate-to-high risk patients who did not receive testing to be $17,000 – 170,000. CONCLUSIONS: Our study confirms our hypothesis that low-risk patients were being inappropriately tested and that moderate-to-high risk patients were not receiving appropriate testing prior to discharge or within 72 hours of discharge. This data is also consistent when patients were further categorized by gender, ethnicity, and insurance type. CLINICAL IMPLICATIONS: Proper risk-stratification and ensuring appropriate use of noninvasive testing would decrease healthcare expenditures. These savings may be better utilized on primary prevention and education to prevent future morbidity and readmissions. We would like to perform a Phase II of the study which would entail a goal of a 15% decrease in inappropriately ordered noninvasive testing for low-risk patients and a 15% increase in appropriately ordered testing for moderate-to-high-risk patients. DISCLOSURES: No relevant relationships by Jonathan Crosby, source=Web Response No relevant relationships by Jonathan Lee, source=Web Response

In this paper we introduce shared, verifiable database tables, a new abstraction for trusted data sharing in the cloud.

This paper introduces Spice, a system for building verifiable state machines (VSMs). A VSM is a request-processing service that produces proofs establishing that requests were executed correctly according to a specification. Such proofs are succinct (a verifier can check them efficiently without reexecution) and zero-knowledge (a verifier learns nothing about the content of the requests, responses, or the internal state of the service). Recent systems for proving the correct execution of stateful computations--Pantry [25], Geppetto [34], CTV [30], vSQL [83], etc.--implicitly implement VSMs, but they incur prohibitive costs. Spice reduces these costs significantly with a new storage primitive. More notably, Spice's storage primitive supports multiple writers, making Spice the first system that can succinctly prove the correct execution of concurrent services. We find that Spice running on a cluster of 16 servers achieves 488-1167 transactions/second for a variety of applications including inter-bank transactions [27], cloud-hosted ledgers [28], and dark pools [63]. This represents an 18,000-685,000× higher throughput than prior work.