Aegis: A Lightning Fast Privacy-preserving Machine Learning Platform against Malicious Adversaries

Privacy-preserving machine learning (PPML) techniques have gained significant popularity in the past years. Those protocols have been widely adopted in many real-world security-sensitive machine learning scenarios, e.g., medical care and finance. In this work, we introduce $\mathsf{Aegis}$~-- a high-performance PPML platform built on top of a maliciously secure 3-PC framework over ring $\mathbb{Z}_{2^\ell}$. In particular, we propose a novel 2-round secure comparison (a.k.a., sign bit extraction) protocol in the preprocessing model. The communication of its semi-honest version is only 25% of the state-of-the-art (SOTA) constant-round semi-honest comparison protocol by Zhou et al.(S&P 2023); both communication and round complexity of its malicious version are approximately 50% of the SOTA (BLAZE) by Patra and Suresh (NDSS 2020), for $\ell=64$. Moreover, the communication of our maliciously secure inner product protocol is merely $3\ell$ bits, reducing 50% from the SOTA (Swift) by Koti et al. (USENIX 2021). Finally, the resulting ReLU and MaxPool PPML protocols outperform the SOTA by $4\times$ in the semi-honest setting and $10\times$ in the malicious setting, respectively

Multi-party Private Function Evaluation for RAM

Private function evaluation (PFE) is a special type of MPC protocols that, in addition to the input privacy, can preserve the function privacy. In this work, we propose a PFE scheme for RAM. In particular, we first design an efficient 4-server distributed ORAM scheme with amortized communication $O(\log n)$ per access (both reading and writing). We then simulate a RISC RAM machine over the MPC platform, hiding (i) the memory access pattern, (ii) the machine state (including registers, program counter, condition flag, etc.), and (iii) the executed instructions. Our scheme can naturally support a simplified TinyRAM instruction set; if a public RAM program $P$ with given inputs $x$ needs to execute $z$ instruction cycles, our PFE scheme is able to securely evaluate $P(x)$ on private $P$ and $x$ within $5z+1$ online rounds. We prototype and benchmark our system for set intersection, binary search, quicksort, and heapsort algorithms. For instance, to obliviously perform the binary search algorithm on a $2^{10}$ array takes $5.81s$ with function privacy

UC Secure Private Branching Program and Decision Tree Evaluation

Branching program (BP) is a DAG-based non-uniform computational model for L/poly class. It has been widely used in formal verification, logic synthesis, and data analysis. As a special BP, a decision tree is a popular machine learning classifier for its effectiveness and simplicity. In this work, we propose a UC-secure efficient 3-party computation platform for outsourced branching program and/or decision tree evaluation. We construct a constant-round protocol and a linear-round protocol. In particular, the overall (online + offline) communication cost of our linear-round protocol is $O(d(\ell + \log m+\log n))$ and its round complexity is $2d-1$, where $m$ is the DAG size, $n$ is the number of features, $\ell$ is the feature length, and $d$ is the longest path length. To enable efficient oblivious hopping among the DAG nodes, we propose a lightweight $1$-out-of-$N$ shared OT protocol with logarithmic communication in both online and offline phase. This partial result may be of independent interest to some other cryptographic protocols. Our benchmark shows, compared with the state-of-the-arts, the proposed constant-round protocol is up to 10X faster in the WAN setting, while the proposed linear-round protocol is up to 15X faster in the LAN setting

Protective Effect of a Combined Glutamine and Curcumin Formulation on Alcoholic Gastric Mucosal Damage

Objective: This study aimed to investigate the protective effect and underlying mechanism of a combined glutamine and curcumin formulation on ethanol-induced gastric mucosal damage in rats. Method: A total of fifty SPF-grade healthy SD male rats were randomly partitioned into five groups: A normal group, a model control group, a cimetidine group, a high-dose treatment group, and a low-dose treatment group. After a period of 30 days marked by oral gavage administration, all groups, with the exception of the normal group, were euthanized post anhydrous ethanol-induced modeling. The histopathological alterations in the gastric mucosa were observed via hematoxylin & eosin (H&E) staining. Furthermore, serum levels of malondialdehyde (MDA), nitric oxide (NO), and glutathione peroxidase (GSH-PX) were ascertained using a specific reagent kit. Concurrently, the concentration of prostaglandin E2 (PGE2) within the tissue and the expression levels of heme oxygenase-1 (HO-1), NADPH quinone oxidoreductase (NQO1), the antioxidant-related nuclear factor-E2-related factor 2 (Nrf2) gene, and glycogen synthase kinase-3β (GSK-3β) were evaluated. Results: In the cimetidine and high-dose treatment groups, the incidence of gastric mucosal bleeding and other forms of injury were noticeably mitigated (P<0.05) compared to the model control group, with the high-dose treatment group demonstrating a more pronounced effect. Moreover, the model control group exhibited a significant elevation in MDA content and GSH-PX activity and a concurrent decline in NO and PGE2 levels (P<0.05). The expression of antioxidant-related genes, namely, HO-1, NQO1, and Nrf2, was significantly suppressed (P<0.05), whereas GSK-3β expression was markedly increased. In contrast, in comparison to the model control group, the cimetidine and high-dose treatment groups manifested a significant reduction in MDA content and GSH-PX activity, while NO and PGE2 levels notably increased (P<0.05). The expression of the antioxidant-related genes HO-1, NQO1, and Nrf2 was significantly returned to normal (P<0.05), and GSK-3β expression was suppressed (P<0.05). Conclusion: The combined formulation appears to exert an inhibitory effect on ethanol-induced acute gastric mucosal damage. This effect is hypothesized to be associated with the Keap1-Nrf2-ARE oxidative stress signaling pathway

PPAR-α Agonist Fenofibrate Upregulates Tetrahydrobiopterin Level through Increasing the Expression of Guanosine 5′-Triphosphate Cyclohydrolase-I in Human Umbilical Vein Endothelial Cells

Tetrahydrobiopterin (BH4) is an essential cofactor for endothelial nitric oxide (NO) synthase. Guanosine 5′-triphosphate cyclohydrolase-I (GTPCH-I) is a key limiting enzyme for BH4 synthesis. In the present in vitro study, we investigated whether peroxisome proliferator-activated receptor α (PPAR-α) agonist fenofibrate could recouple eNOS by reversing low-expression of intracellular BH4 in endothelial cells and discussed the potential mechanisms. After human umbilical vein endothelial cells (HUVECs) were treated with lipopolysaccharide (LPS) for 24 hours, the levels of cellular eNOS, BH4 and cell supernatant NO were significantly reduced compared to control group. And the fluorescence intensity of intracellular ROS was significantly increased. But pretreated with fenofibrate (10 umol/L) for 2 hours before cells were induced by LPS, the levels of eNOS, NO, and BH4 were significantly raised compared to LPS treatment alone. ROS production was markedly reduced in fenofibrate group than LPS group. In addition, our results showed that the level of intracellular GTPCH-I detected by western blot was increased in a concentration-dependent manner after being treated with fenofibrate. These results suggested that fenofibrate might help protect endothelial function and against atherosclerosis by increasing level of BH4 and decreasing production of ROS through upregulating the level of intracellular GTPCH-I

Reprogramming bacterial protein organelles as a nanoreactor for hydrogen production

Compartmentalization is a ubiquitous building principle in cells, which permits segregation of biological elements and reactions. The carboxysome is a specialized bacterial organelle that encapsulates enzymes into a virus-like protein shell and plays essential roles in photosynthetic carbon fixation. The naturally designed architecture, semi-permeability, and catalytic improvement of carboxysomes have inspired rational design and engineering of new nanomaterials to incorporate desired enzymes into the protein shell for enhanced catalytic performance. Here, we build large, intact carboxysome shells (over 90 nm in diameter) in the industrial microorganism Escherichia coli by expressing a set of carboxysome protein-encoding genes. We develop strategies for enzyme activation, shell self-assembly, and cargo encapsulation to construct a robust nanoreactor that incorporates catalytically active [FeFe]-hydrogenases and functional partners within the empty shell for the production of hydrogen. We show that shell encapsulation and the internal microenvironment of the new catalyst facilitate hydrogen production of the encapsulated oxygen-sensitive hydrogenases. The study provides insights into the assembly and formation of carboxysomes and paves the way for engineering carboxysome shell-based nanoreactors to recruit specific enzymes for diverse catalytic reactions

Roles of abnormal lipid metabolism in pathogenesis of non-alcoholic fatty liver disease

The prevalence of non-alcoholic fatty liver disease (NAFLD) keeps rising worldwide along with the increasing prevalence of metabolic diseases such as obesity, type 2 diabetes, and dyslipidemia. Although most NAFLD patients present with simple steatosis of hepatocytes, some patients progress to non-alcoholic steatohepatitis, liver cirrhosis, and even cancer. In the Western world, NAFLD is the most common cause of elevated liver enzymes, and hence there has been a growing interest in this disease. Given that fat deposition in the liver is the hallmark of NAFLD, we review the roles and the underlying mechanism of disturbed lipid metabolism in the development of NAFLD and suggest that more insights into the pathogenesis of NAFLD will help develop targeted strategies for the prevention and treatment of this disease

Nanoengineering Carboxysome Shells for Protein Cages with Programmable Cargo Targeting.

Protein nanocages have emerged as promising candidates for enzyme immobilization and cargo delivery in biotechnology and nanotechnology. Carboxysomes are natural proteinaceous organelles in cyanobacteria and proteobacteria and have exhibited great potential in creating versatile nanocages for a wide range of applications given their intrinsic characteristics of self-assembly, cargo encapsulation, permeability, and modularity. However, how to program intact carboxysome shells with specific docking sites for tunable and efficient cargo loading is a key question in the rational design and engineering of carboxysome-based nanostructures. Here, we generate a range of synthetically engineered nanocages with site-directed cargo loading based on an α-carboxysome shell in conjunction with SpyTag/SpyCatcher and Coiled-coil protein coupling systems. The systematic analysis demonstrates that the cargo-docking sites and capacities of the carboxysome shell-based protein nanocages could be precisely modulated by selecting specific anchoring systems and shell protein domains. Our study provides insights into the encapsulation principles of the α-carboxysome and establishes a solid foundation for the bioengineering and manipulation of nanostructures capable of capturing cargos and molecules with exceptional efficiency and programmability, thereby enabling applications in catalysis, delivery, and medicine

Simultaneous Quantitative Determination of Polyphenolic Compounds in Blumea balsamifera (Ai-Na-Xiang, Sembung) by High-Performance Liquid Chromatography with Photodiode Array Detector

A high-performance liquid chromatography method was developed for simultaneous quantification of 18 polyphenolic compounds from the leaves of Blumea balsamifera, including 17 flavonoids and 1 phenylethanone. The B. balsamifera extraction was separated by a Kromasil C18 column (250 × 4.6 mm, 5 μm) with a binary gradient mobile phase consisting of acetonitrile and 0.2% aqueous acetic acid. A photodiode array detector (PDA) was used to record the signals of investigated constituents. The linearity, sensitivity, stability, precision, and accuracy of the established assay methods were assessed to meet the requirements of quantitative determination. Samples extracted by reflux in 25 mL of 80% methanol for 30 minutes were selected for the extraction method. The 18 compounds were accurately identified by comparing with the reference compounds. The purity of each peak was confirmed by the base peak in the mass spectrum. The contents of 18 compounds in Blumea samples from four different regions were successfully determined. The results also showed that 3,3′,5,7-tetrahydroxy-4′-methoxyflavanone was the most abundant constituent, which could be used as a potential chemical marker for quality control of B. balsamifera and Chinese patent medications containing B. balsamifera herb