Succinct Randomized Encodings and their Applications

A {\em randomized encoding} allows to represent a ``complex\u27\u27 function $f(x)$ by a ``simpler\u27\u27 randomized function $\hat{f}(x;r)$ whose output distribution encodes $f(x)$, while revealing nothing else regarding $x$. Existing randomized encodings, geared mostly to allow encoding with low parallel complexity, have proven instrumental in various strong applications such as multiparty computation and parallel cryptography. This work focuses on another natural complexity measure: {\em the time required to encode}. We construct {\em succinct randomized encodings} where a computation given by a (Turing or random-access) machine $M$, and input $x$, requiring time $t$ and space $s$, can be encoded roughly in time \poly(|x|,\log t,s), thus inducing significant savings in time when $s \ll t$. The scheme guarantees computational input-privacy and is based on indistinguishability obfuscation for a relatively simple circuit class, which can in turn be based on a polynomial version of the subgroup elimination assumption on multilinear graded encodings. We then invoke succinct randomized encodings to obtain several strong applications, including: \begin{itemize} \item Indistinguishability obfuscation for uniform (Turing or random-access) machines, where the obfuscated machine \iO(M) computes the same function as $M$ for inputs $x$ of apriori-fixed maximal size $n$, and is computed in time \poly(n,\log t,s). \item Functional encryption for uniform machines, where a functional decryption key corresponding to $M$ allows decrypting $M(x)$ from encryptions of $x$. As in the previous case, inputs $x$ are of apriori-fixed maximal size $n$, and key derivation time is roughly \poly(n,\log t,s). \item Publicly-verifiable 2-message delegation where verification time is roughly \poly(n,\log t,s). We also show how to transform any 2-message delegation scheme to an essentially non-interactive system where the verifier message is reusable. \end{itemize} For the first application, we also require subexponentially-secure indistinguishability obfuscation for circuits, and for the second polynomial indistinguishability obfuscation, which can be replaced by more concrete polynomial hardness assumptions on multilinear graded-encodings. Previously, both applications were only known based on various non-standard knowledge assumptions

Succinct Randomized Encodings and their Applications

A {\em randomized encoding} allows to express a ``complex\u27\u27 computation, given by a function $f$ and input $x$, by a ``simple to compute\u27\u27 randomized representation $\hat{f}(x)$ whose distribution encodes $f(x)$, while revealing nothing else regarding $f$ and $x$. Existing randomized encodings, geared mostly to allow encoding with low parallel-complexity, have proven instrumental in various strong applications such as multiparty computation and parallel cryptography. This work focuses on another natural complexity measure: {\em the time required to encode}. We construct {\em succinct randomized encodings} where the time to encode a computation, given by a program $\Pi$ and input $x$, is essentially independent of $\Pi$\u27s time complexity, and only depends on its space complexity, as well as the size of its input, output, and description. The scheme guarantees computational privacy of $(\Pi,x)$, and is based on indistinguishability obfuscation for a relatively simple circuit class, for which there exist instantiations based on polynomial hardness assumptions on multi-linear maps. We then invoke succinct randomized encodings to obtain several strong applications, including: \begin{itemize} \item Succinct indistinguishability obfuscation, where the obfuscated program $iO({\Pi})$ computes the same function as $\Pi$ for inputs $x$ of apriori-bounded size. Obfuscating $\Pi$ is roughly as fast as encoding the computation of $\Pi$ on any such input $x$. Here we also require subexponentially-secure indistinguishability obfuscation for circuits. \item Succinct functional encryption, where a functional decryption key corresponding to $\Pi$ allows decrypting $\Pi(x)$ from encryptions of any plaintext $x$ of apriori-bounded size. Key derivation is as fast as encoding the corresponding computation. \item Succinct reusable garbling, a stronger form of randomized encodings where any number of inputs $x$ can be encoded separately of $\Pi$, independently of $\Pi$\u27s time and space complexity. \item Publicly-verifiable 2-message delegation where verifying the result of a long computation given by $\Pi$ and input $x$ is as fast as encoding the corresponding computation. We also show how to transform any 2-message delegation scheme to an essentially non-interactive system where the verifier message is reusable. \end{itemize} Previously, succinct randomized encodings or any of the above applications were only known based on various non-standard knowledge assumptions. At the heart of our techniques is a generic method of compressing a piecemeal garbled computation, without revealing anything about the secret randomness utilized for garbling

EphH, a unique epoxide hydrolase encoded by Rv3338 is involved in the survival of Mycobacterium tuberculosis under in vitro stress and vacuolar pH-induced changes

IntroductionMycobacterium tuberculosis (Mtb), one of the deadliest human pathogen, has evolved with different strategies of survival inside the host, leading to a chronic state of infection. Phagosomally residing Mtb encounters a variety of stresses, including increasing acidic pH. To better understand the host-pathogen interaction, it is imperative to identify the role of various genes involved in the survivability of Mtb during acidic pH environment.MethodsBio-informatic and enzymatic analysis were used to identify Mtb gene, Rv3338, as epoxide hydrolase. Subsequently, CRISPRi knockdown strategy was used to decipher its role for Mtb survival during acidic stress, nutrient starvation and inside macrophages. Confocal microscopy was used to analyse its role in subverting phagosomal acidification within macrophage.ResultsThe present work describes the characterization of Rv3338 which was previously known to be associated with the aprABC locus induced while encountering acidic stress within the macrophage. Bio-informatic analysis demonstrated its similarity to epoxide hydrolase, which was confirmed by enzymatic assays, thus, renamed EphH. Subsequently, we have deciphered its indispensable role for Mtb in protection from acidic stress by using the CRISPRi knockdown strategy. Our data demonstrated the pH dependent role of EphH for the survival of Mtb during nutrient starvation and in conferring resistance against elevated endogenous ROS levels during stress environment.ConclusionTo the best of our knowledge, this is the first report of an EH of Mtb as a crucial protein for bacterial fitness inside the host, a phenomenon central to its pathogenesis

Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC

Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe

Melasma update

Melasma is an acquired pigmentary disorder characterized by symmetrical hyperpigmented macules on the face. Its pathogenesis is complex and involves the interplay of various factors such as genetic predisposition, ultraviolet radiation, hormonal factors, and drugs. An insight into the pathogenesis is important to devise treatment modalities that accurately target the disease process and prevent relapses. Hydroquinone remains the gold standard of treatment though many newer drugs, especially plant extracts, have been developed in the last few years. In this article, we review the pathogenetic factors involved in melasma. We also describe the newer treatment options available and their efficacy. We carried out a PubMed search using the following terms "melasma, pathogenesis, etiology, diagnosis, treatment" and have included data of the last few years

A Fresh Look on Bergenin: Vision of Its Novel Drug Delivery Systems and Pharmacological Activities

Bergenin (BER), a key constituent of Bergenia crassifolia (Saxifragaceae), has gained extensive attention, owing to its array of pharmacological actions, including anti-infective, anti-cancer, anti-diabetic, neuroprotective, hepatoprotective, anti-urolithiatic, anti-hyperuricemic, and anti-bradykinin properties. Despite ever-intensifying support for its therapeutic features, the poor solubility, lower oral bioavailability, shorter half-life, and more intestinal pH degradation (pH 6.8 or above) of BER have puzzled researchers. To circumvent these pharmaceutical challenges, and to improve its therapeutic efficacy, newer approaches have been adopted by research scientists. Thus, a discussion of the existing literature may provide complete information about the advances in delivery strategies for enhancing its utility. This paper summarizes up-to-date works on the design and development of novel delivery carriers of this bioactive compound, such as phospholipid complexes, extended-release core tablets, prodrugs, herbal gels, polyherbal ointments, nanoparticles, and poly (lactic acid) polymers, with the objective of harnessing its full potential. This review also provides a deep insight into its bioactivities, along with mechanisms. Additionally, the physicochemical attributes, chemistry, and pharmacokinetics of BER are discussed herein. Hence, the comprehensive information documented in this review may introduce new avenues for research advancements of BER

Indistinguishability Obfuscation for RAM Programs and Succinct Randomized Encodings

© 2018 Society for Industrial and Applied Mathematics. We show how to construct indistinguishability obfuscation (\bfi/bfO) for RAM programs with bounded space, assuming/bfi/bfO for circuits and one-way functions, both with subexponential security. That is, given a RAM program whose computation requires space s(n) in the worst case for inputs of length at most n, we generate an obfuscated RAM program that, for inputs of size at most n, runs in roughly the same time as the original program, using space roughly s(n). The obfuscation process is quasi-linear in the description length of the input program and s(n). At the heart of our construction are succinct randomized encodings for RAM programs. We present two very different constructions of such encodings, each with its own unique properties. Beyond their use as a tool in obfuscation for RAM programs, we show that succinct randomized encodings are interesting objects in their own right. We demonstrate the power of succinct randomized encodings in applications such as publicly verifiable delegation, functional encryption for RAMs, and key-dependent security amplification