Bicoptor 2.0: Addressing Challenges in Probabilistic Truncation for Enhanced Privacy-Preserving Machine Learning

This paper primarily focuses on analyzing the problems and proposing solutions for the probabilistic truncation protocol in existing PPML works from the perspectives of accuracy and efficiency. In terms of accuracy, we reveal that precision selections recommended in some of the existing works are incorrect. We conduct a thorough analysis of their open-source code and find that their errors were mainly due to simplified implementation, more specifically, fixed numbers are used instead of random numbers in probabilistic truncation protocols. Based on this, we provide a detailed theoretical analysis to validate our views. We propose a solution and a precision selection guideline for future works. Regarding efficiency, we identify limitations in the state-of-the-art comparison protocol, Bicoptor's (S\&P 2023) DReLU protocol, which relies on the probabilistic truncation protocol and is heavily constrained by the security parameter to avoid errors, significantly impacting the protocol's performance. To address these challenges, we introduce the first non-interactive deterministic truncation protocol, replacing the original probabilistic truncation protocol. Additionally, we design a non-interactive modulo switch protocol to enhance the protocol's security. Finally, we provide a guideline to reduce computational and communication overhead by using only a portion of the bits of the input, i.e., the key bits, for DReLU operations based on different model parameters. With the help of key bits, the performance of our DReLU protocol is further improved. We evaluate the performance of our protocols on three GPU servers, and achieve a 10x improvement in DReLU protocol, and a 6x improvement in the ReLU protocol over the state-of-the-art work Piranha-Falcon (USENIX Sec 22). Overall, the performance of our end-to-end (E2E) privacy-preserving machine learning (PPML) inference is improved by 3-4 times.Comment: 17 pages, 5 figure

HEAD: an FHE-based Privacy-preserving Cloud Computing Protocol with Compact Storage and Efficient Computation

Fully homomorphic encryption (FHE) provides a natural solution for privacy-preserving cloud computing, but a straightforward FHE protocol may suffer from high computational overhead and a large ciphertext expansion rate, especially for computation-intensive tasks over large data, which are the main obstacles toward practical privacy-preserving cloud computing. In this paper, we present HEAD, a generic privacy-preserving cloud computing protocol that can be based on most mainstream (typically a BGV or GSW style scheme) FHE schemes with more compact storage and less computational costs than the straightforward FHE counterpart. In particular, our protocol enjoys a ciphertext/plaintext expansion rate of 1 (i.e., no expansion) in a cloud computing server, instead of a factor of hundreds of thousands. This is achieved by means of ``pseudorandomly masked\u27\u27 ciphertexts, and the efficient transformations of them into FHE ciphertexts to facilitate privacy-preserving cloud computing. Depending on the underlying FHE in use, our HEAD protocol can be instantiated with the three masking techniques, namely modulo-subtraction-masking, modulo-division-masking, and XOR-masking, to support the decimal integer, real, or binary messages. Thanks to these masking techniques, various homomorphic computation tasks are made more efficient and less prone to noise accumulation. Furthermore, our multi-input masking and unmasking operations are more flexible than the FHE SIMD-batching, by supporting an on-demand configuration of FHE during each cloud computing request. We evaluate the performance of HEAD protocols on BFV, BGV, CKKS, and FHEW schemes based on the PALISADE and SEAL libraries, which confirms the theoretical analysis of the storage savings, the reduction in terms of computational complexity and noise accumulation. For example, in the BFV computation optimization, the sum or product of eight ciphertexts overhead is reduced from 336.3 ms to 6.3 ms, or from 1219.4 ms to 9.5 ms, respectively. We also embed HEAD into a mainstream database, PostgreSQL, in a client-server cloud storage and computing style. Compared with a straightforward FHE protocol, our experiments show that HEAD does not incur ciphertext expansion, and exhibits at least an order of magnitude saving in computing time at the server side for various tasks (on a hundred ciphertexts), by paying a reasonable price in client pre-processing time and communication. Our storage advantage not only gets around the database storage limitation but also reduces the I/O overhead

TPST2-mediated receptor tyrosine sulfation enhances leukocidin cytotoxicity and S. aureus infection

BackgroundAn essential fact underlying the severity of Staphylococcus aureus (S. aureus) infection is the bicomponent leukocidins released by the pathogen to target and lyse host phagocytes through specific binding cell membrane receptors. However, little is known about the impact of post-transcriptional modification of receptors on the leukocidin binding.MethodIn this study, we used small interfering RNA library (Horizon/Dharmacon) to screen potential genes that affect leukocidin binding on receptors. The cell permeability was investigated through flow cytometry measuring the internalization of 4′,6-diamidino-2-phenylindole. Expression of C5a anaphylatoxin chemotactic receptor 1 (C5aR1), sulfated C5aR1 in, and binding of 6x-His–tagged Hemolysin C (HlgC) and Panton-Valentine leukocidin (PVL) slow-component to THP-1 cell lines was detected and analyzed via flow cytometry. Bacterial burden and Survival analysis experiment was conducted in WT and myeloid TPST-cko C57BL/6N mice.ResultsAfter short hairpin RNA (shRNA) knockdown of TPST2 gene in THP-1, HL-60, and RAW264.7, the cytotoxicity of HlgAB, HlgCB, and Panton–Valentine leukocidin on THP-1 or HL-60 cells was decreased significantly, and the cytotoxicity of HlgAB on RAW264.7 cells was also decreased significantly. Knockdown of TPST2 did not affect the C5aR1 expression but downregulated cell surface C5aR1 tyrosine sulfation on THP-1. In addition, we found that the binding of HlgC and LukS-PV on cell surface receptor C5aR1 was impaired in C5aR1+TPST2− and C5aR1−TPST2− cells. Phagocyte knockout of TPST2 protects mice from S. aureus infection and improves the survival of mice infected with S. aureus.ConclusionThese results indicate that phagocyte TPST2 mediates the bicomponent leukocidin cytotoxicity by promoting cell membrane receptor sulfation modification that facilitates its binding to leukocidin S component

Controlled Synthesis of Water-Soluble NaYF4:Yb3+, Er3+ Nanoparticles with Surfactant Dependent Properties

Water-soluble NaYF4:Yb3+, Er3+ nanoparticles (NPs) are successfully prepared by a solvothermal reaction using branched polyethylenimine (PEI) with different chain lengths as the surfactants in a water/diethylene glycol (DEG) mixed solution. It is shown that the size of NaYF4 NPs prepared with high molecular weight PEI (HPEI) is smaller than that of the NPs prepared with low molecular weight (LPEI), while small-sized NPs exhibit more intense upconversion luminescence intensities than large-sized NPs in the same excitation power of 980 nm. It is found that HPEI is conducive to the formation of smaller NP with high crystallinity. Small-sized NaYF4:Yb3+, Er3+ NPs with intense upconversion luminescence and improved crystallinity were related to their growth process. A possible growth mechanism of the samples is proposed. The results of this study can provide new insights into the controlled synthesis of novel NPs

Regulation Mechanism of ssDNA Aptamer in Nanozymes and Application of Nanozyme-Based Aptasensors in Food Safety

Food safety issues are a worldwide concern. Pathogens, toxins, pesticides, veterinary drugs, heavy metals, and illegal additives are frequently reported to contaminate food and pose a serious threat to human health. Conventional detection methods have difficulties fulfilling the requirements for food development in a modern society. Therefore, novel rapid detection methods are urgently needed for on-site and rapid screening of massive food samples. Due to the extraordinary properties of nanozymes and aptamers, biosensors composed of both of them provide considerable advantages in analytical performances, including sensitivity, specificity, repeatability, and accuracy. They are considered a promising complementary detection method on top of conventional ones for the rapid and accurate detection of food contaminants. In recent years, we have witnessed a flourishing of analytical strategies based on aptamers and nanozymes for the detection of food contaminants, especially novel detection models based on the regulation by single-stranded DNA (ssDNA) of nanozyme activity. However, the applications of nanozyme-based aptasensors in food safety are seldom reviewed. Thus, this paper aims to provide a comprehensive review on nanozyme-based aptasensors in food safety, which are arranged according to the different interaction modes of ssDNA and nanozymes: aptasensors based on nanozyme activity either inhibited or enhanced by ssDNA, nanozymes as signal tags, and other methods. Before introducing the nanozyme-based aptasensors, the regulation by ssDNA of nanozyme activity via diverse factors is discussed systematically for precisely tailoring nanozyme activity in biosensors. Furthermore, current challenges are emphasized, and future perspectives are discussed.https://doi.org/10.3390/foods1104054

Recent Developments in Food Packaging Based on Nanomaterials

The increasing demand for high food quality and safety, and concerns of environment sustainable development have been encouraging researchers in the food industry to exploit the robust and green biodegradable nanocomposites, which provide new opportunities and challenges for the development of nanomaterials in the food industry. This review paper aims at summarizing the recent three years of research findings on the new development of nanomaterials for food packaging. Two categories of nanomaterials (i.e., inorganic and organic) are included. The synthetic methods, physical and chemical properties, biological activity, and applications in food systems and safety assessments of each nanomaterial are presented. This review also highlights the possible mechanisms of antimicrobial activity against bacteria of certain active nanomaterials and their health concerns. It concludes with an outlook of the nanomaterials functionalized in food packaging