1,181 research outputs found
On the Round Complexity Landscape of Secure Multi-party Computation
No full textIn secure multi-party computation (MPC), n parties wish to jointly perform a computation on their private inputs in a secure way, so that no adversary corrupting a subset of the parties can learn more information than their outputs (privacy), nor can they affect the outputs of the computation other than by choosing their own inputs (correctness). The round complexity of MPC protocols is a fundamental question in the area of secure computation and its study constitutes a phenomenal body of work in the MPC literature. The research goal of this thesis is to advance the state of the art by expanding this study of round complexity to various adversarial settings and network models. Following are the main contributions of this thesis organized into three broad categories:
(1) MPC for small population-
We begin with the study of round-optimal (more generally, round-efficient) MPC protocols for small population, namely involving 3 (3PC) and 4 (4PC) parties tolerating single active corruption (honest majority). On the theoretical side, we settle the exact round complexity of 3PC in honest-majority setting, for a range of security notions such as selective abort (adversary can selectively deprive some honest parties of the output), unanimous abort (either all or none of the honest parties get the output), fairness (adversary gets output only if honest parties do) and guaranteed output delivery (adversary cannot prevent honest parties from obtaining the output). On the practical side, we present efficient, constant-round 3PC and 4PC protocols with fairness and guaranteed output delivery; suitable for high-latency networks such as the Internet. This work is based on [1, 2].
(2) Beyond Traditional Adversaries -
We extend the study of round complexity beyond the traditional adversarial settings. First, we overcome the demarcation of study of round complexity of MPC based on resilience (i.e. honest majority or dishonest majority settings) and investigate an interesting class of protocols called the Best-of-both-Worlds (BoBW) MPC which simultaneously achieve fairness / guaranteed output delivery in honest majority and unanimous abort in dishonest majority. We nearly settle the question of exact round complexity of BoBW protocols for several popular setups of MPC such as the plain model, public setup and private setup. This work is based on [3].
Second, we overcome the demarcation of study of round complexity of MPC based on single type of corruption i.e. either purely passive (adversary follows the protocol steps but tries to learn more information) or active (adversary is allowed to deviate from the protocol in any arbitrary way). We consider a generalized adversarial setting where the adversary can simultaneously perform both kinds of corruptions. We settle the question of exact round complexity of MPC protocols achieving fairness and guaranteed output delivery against two such generalized and powerful adversaries called the dynamic and boundary adversaries; in the public setup model. These results appear in [4].
(3) Power of Hybrid Networks -
A popular categorization of study of MPC based on network is the synchronous and asynchronous setting. On one hand, asynchronous networks (channels are allowed to have arbitrary delays) are more realistic but on the other, synchronous protocols (channels have bounded delay) are known to have better fault tolerance and properties compared to their asynchronous counterparts. With the goal of combining their best features, we explore hybrid networks that is asynchronous in nature and yet supports a few synchronous rounds at the onset of a protocol execution.
We address fundamental questions that throw light on the minimal synchrony assumption needed (in terms of the number of initial synchronous rounds in the hybrid network) to achieve the properties of the fully synchronous protocols. We bridge the existing theoretical feasibility gap between perfectly-secure (tolerate unbounded adversaries with no error) synchronous and asynchronous VSS and MPC protocols; where verifiable secret sharing (VSS) constitutes a fundamental building block of MPC. These results appear in [5].
References:
[1] Arpita Patra and Divya Ravi. On the exact round complexity of secure three-party
computation. In CRYPTO, 2018.
[2] Megha Byali, Arun Joseph, Arpita Patra, and Divya Ravi. Fast secure computation for
small population over the internet. In ACM Conference of Computer and Communications Security (CCS), 2018.
[3] Arpita Patra, Divya Ravi and Swati Singla. On the Exact Round Complexity of Best-of-both-Worlds Multi-party Computation. In ASIACRYPT, 2020.
[4] Arpita Patra and Divya Ravi. Beyond honest majority: The round complexity of fair
and robust multi-party computation. In ASIACRYPT, 2019.
[5] Arpita Patra and Divya Ravi. On the power of hybrid networks in multi-party computation.
IEEE Trans. Inf. Theory, 64(6):4207–4227, 2018
Brief Announcement: Crash-Tolerant Consensus in Directed Graph Revisited
No full textWe revisit the problem of distributed consensus in directed graphs tolerating crash failures; we improve the round and communication complexity of the existing protocols. Moreover, we prove that our protocol requires the optimal number of communication rounds, required by any protocol belonging to a specific class of crash-tolerant consensus protocols in directed graphs
Secure Communication in Dynamic Incomplete Networks
No full textIn this paper, we explore the feasibility of reliable and private communication in dynamic networks, where in each round the adversary can choose which direct peer-to-peer links are available in the network graph, under the sole condition that the graph is k-connected at each round (for some k).
We show that reliable communication is possible in such a dynamic network if and only if k > 2t. We also show that if k = cn > 2 t for a constant c, we can achieve reliable communication with polynomial round and communication complexity.
For unconditionally private communication, we show that for a passive adversary, k > t is sufficient (and clearly necessary). For an active adversary, we show that k > 2t is sufficient for statistical security (and clearly necessary), while k > 3t is sufficient for perfect security. We conjecture that, in contrast to the static case, k > 2t is not enough for perfect security, and we give evidence that the conjecture is true.
Once we have reliable and private communication between each pair of parties, we can emulate a complete network with secure channels, and we can use known protocols to do secure computation
Synthesis of Al and Ag nanoparticles through ultra-sonic dissociation of thermal evaporation deposited thin films for promising clinical applications as polymer nanocomposite
No full textNanoparticles (NPs) having well-defined shape, size and clean surface serve as ideal model system to investigate surface/interfacial reactions. Ag and Al NPs are receiving great interest due to their wide applications in bio-medical field, aerospace and space technology as combustible additives in propellants and hydrogen generation. Hence, in this study, we have synthesized Ag and Al NPs using an innovative approach of ultra-sonic dissociation of thin films. Phase and particle size distributions of the Ag and Al NPs have been determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Thin film dissociation/dissolution mechanism, hence conversion into NPs has been characterized by SEM- scanning electron microscope. EDXA & ICPMS have been performed for chemical analysis of NPs. Optical properties have been characterized by UV-Vis and PL spectroscopy. These NPs have also been investigated for their anti-bacterial activity against Escherichia coli bacteria. To the best of our knowledge, this is the first time when NPs has been synthesized by ultra-sonic dissociation of thin films. As an application, these NPs were used further for synthesis of nanocomposite polymer membranes, which show excellent activity against bio film formation
MPC with Low Bottleneck-Complexity: Information-Theoretic Security and More
No full textThe bottleneck-complexity (BC) of secure multiparty computation (MPC) protocols is a measure of the maximum number of bits which are sent and received by any party in protocol. As the name suggests, the goal of studying BC-efficient protocols is to increase overall efficiency by making sure that the workload in the protocol is somehow "amortized" by the protocol participants.
Orlandi et al. [Orlandi et al., 2022] initiated the study of BC-efficient protocols from simple assumptions in the correlated randomness model and for semi-honest adversaries. In this work, we extend the study of [Orlandi et al., 2022] in two primary directions: (a) to a larger and more general class of functions and (b) to the information-theoretic setting.
In particular, we offer semi-honest secure protocols for the useful function classes of abelian programs, "read-k" non-abelian programs, and "read-k" generalized formulas.
Our constructions use a novel abstraction, called incremental function secret-sharing (IFSS), that can be instantiated with unconditional security or from one-way functions (with different efficiency trade-offs)
Sweetners perception of polyols
No full textThis Dissertation / Report is the outcome of investigation carried out by the creator(s) / author(s) at the department/division of Central Food Technological Research Institute (CFTRI), Mysore mentioned below in this page
Ovarian Clear Cell Adenofibroma of Low Malignant Potential developing into Clear Cell Adenocarcinoma
No full textOvarian clear cell adenofibroma is uncommon, and borderline clear cell adenofibroma (low malignant potential) is extremely rare. Borderline clear cell adenofibromas may represent the precursor lesion of clear cell adenocarcinoma of the ovary, but this has not been established. We present a case of a woman in her mid-fifties with a clear cell adenofibroma ranging from benign to borderline to frankly invasive. While some clear cell adenocarcinomas are thought to arise from endometriosis, this range of findings supports the theory that some ovarian clear cell adenocarcinomas originate from borderline tumors.Peer reviewe
Scoping study of research trends on Nili Ravi buffalo applying scientometric analysis and network visualization
No full textThe study elucidates scientometric analysis of published scientific communications on Nili Ravi buffalo in journal(s) for having an appraisal of status-quo of the research and scientific activities. Metadata of 383 articles retrieved from Scopus were analysed to identify the most productive author(s), institution(s) vis-a-vis countries and to ascertain their collaboration trends. Keyword based analysis was performed to provide an overview of the strength areas of research on Nili Ravi for better comprehension. The results revealed that the research efforts on Nili Ravi were discernible after the year 2005. All except 1.30% articles have been an outcome of the collaborative authorship. There were only few productive authors with ≥10 records, but others contributed on the subject occasionally. Nearly 90% of the articles have been contributed by Pakistan and its' authors have worked in close collaboration with scientists from United Kingdom, United States of America, China, Canada, and South Korea. They also have conjoint symbiosis on academic/research endavours on Nili Ravi with experts from Austria, Netherlands, India, Germany, Italy, and Australia. Twelve leading institutions contributed to ≥10 articles. Publication outcome of the Animal Sciences Institute, National Agricultural Research Centre, Islamabad, Pakistan; Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi, Pakistan; University of Gujrat, Gujrat, Pakistan and Semen Production Unit, Qadirabad, Sahiwal, Pakistan has higher Relative Citation Impact (RCI), making it obvious that their publication(s) have wider acceptance amongst scientific populace. Most productive vis-à-vis impactful journals publishing articles on Nili Ravi have also been identified
Massive Cellular Angiofibroma of the Vulva
No full textCellular angiofibromas of the vulva are uncommon, and usually small and circumscribed. A massive cellular angiofibroma extending into the pelvis is described.Peer reviewe
Correction: Cu(<scp>i</scp>)-catalyzed double C–H amination: synthesis of 2-iodo-imidazo[1,2-a]pyridines
No full textCorrection for ‘Cu(i)-catalyzed double C–H amination: synthesis of 2-iodo-imidazo[1,2-a]pyridines’ by Divya Dheer et al., RSC Adv., 2016, 6, 38033–38036.</p
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