Search for: All records

Abstract Generating high-quality synthetic networks with realistic community structure is vital to effectively evaluate community detection algorithms. In this study, we propose a new synthetic network generator called the Edge-Connected Stochastic Block Model (EC-SBM). The goal of EC-SBM is to take a given clustered real-world network and produce a synthetic network that resembles the clustered real-world network with respect to both network and community-specific criteria. In particular, we focus on simulating the internal edge connectivity of the clusters in the reference clustered network. Our performance study on large real-world networks shows that EC-SBM is generally more accurate with respect to network and community criteria than currently used approaches for this problem. Furthermore, we demonstrate that EC-SBM can complete analyses on several real-world networks with millions of nodes. 

Secret sharing (SS) is a foundational cryptographic primitive with diverse applications, including secure multiparty computation and conditional disclosure of secrets. While traditional schemes have primarily emphasized information-theoretic security, recent advancements have increasingly leveraged computational assumptions to achieve more efficient constructions and support broader access policies. Despite these successes, most existing computational secret sharing (CSS) schemes are limited to a static security model, where adversaries must commit to their choice of corrupted participants at the outset. A critical challenge in CSS lies in achieving adaptive security, where adversaries can dynamically select participants to corrupt, better reflecting real-world threat models. In this paper, we present a novel transformation that converts any statically secure CSS scheme into an adaptively secure one while preserving the original access policy and computational assumptions, providing a framework for bridging the gap between static and adaptive security. Our construction introduces a multiplicative share size overhead of where is the number of parties. Additionally, we explore trade-offs in efficiency and security, offering more efficient adaptive CSS constructions for specific, restricted policy classes. This work addresses key limitations in the current landscape of CSS and paves the way for broader adoption of adaptively secure secret sharing in cryptographic applications. 

Ten new ruthenium compounds based on the N,N,N,N-chelate Me2bpbMe2 (bpb = 1,2-bis(pyridine-2-carboximido)benzene) have prepared and characterized by 1H NMR and IR spectroscopy. The monocarbonyl compound (Me2bpbMe2)Ru(CO)(H2O) compound was generated from the reaction of the free base Me2bpbMe2H2 with Ru3(CO)12 in refluxing DMF. Isoamyl nitrite reacts with this compound to yield the trans-addition nitrosyl alkoxide (Me2bpbMe2)Ru(NO)(O-i-C5H11). Nitrosothiols similarly add in a formal trans-addition manner to yield (Me2bpbMe2)Ru(NO)(SR/Ar) (SR/Ar = S-i-C5H11, SPh, SC6F4H, SC(Me)2CHNHC(O)Me) derivatives. The (Me2bpbMe2)Ru(NO)(O-i-C5H11) compound undergoes alkoxide exchange reactions with PhOH and HOC6F4H to generate (Me2bpbMe2)Ru(NO)(OPh) and (Me2bpbMe2)Ru(NO)(OC6F4H), respectively. The neutral alkoxide/aryloxide nitrosyl compounds exhibit higher NO bands (1809–1842 cm-1) relative to their thiolate analogues (1755–1823 cm-1). The X-ray crystal structures of (Me2bpbMe2)Ru(NO)(OPh), (Me2bpbMe2)Ru(NO)(OC6F4H), and (Me2bpbMe2)Ru(NO)(SPh), have been determined, and reveal linear axial (O)N–Ru–O/S linkages consistent with trans positioning of the NO and aryloxide and -thiolate groups, and near-linear Ru–N–O moieties (164–174°) consistent with these complexes being formulated as {RuNO}6 species. The electrooxidation behavior of (Me2bpbMe2)Ru(NO)(OC6F4H), (Me2bpbMe2)Ru(NO)(SC6F4H), and (Me2bpbMe2)Ru(NO)(SPh) were examined by cyclic voltammetry and IR spectroelectrochemistry in CH2Cl2. (Me2bpbMe2)Ru(NO)(OC6F4H) and (Me2bpbMe2)Ru(NO)(SC6F4H) display reversible first oxidations, whereas (Me2bpbMe2)Ru(NO)(SPh) displays an irreversible first oxidation with likely loss of the thiolate ligand. Chemical reactivity of (Me2bpbMe2)Ru(NO)(SPh) with H+ and Me+ results in the generation of the free thiol PhSH and thioether PhSMe, respectively.