A modified eCK model with stronger security for tripartite authenticated key exchange

Since Bellare and Rogaway presented the first formal security model for authenticated key exchange (AKE) protocols in 1993, many formal security models have been proposed. The extended Canetti-Krawczyk (eCK) model proposed by LaMacchia et al. is currently regarded as the strongest security model for two-party AKE protocols. In this paper, we first generalize the eCK model for tripartite AKE protocols, called teCK model, and enhance the security of the new model by adding a new reveal query. In the teCK model, the adversary has stronger powers, and can learn more secret information. Then we present a new tripartite AKE protocol based on the NAXOS protocol, called T-NAXOS protocol, and analyze its security in the teCK model under the random oracle assumption

Implicit Factorization with Shared Any Bits

At PKC 2009, May and Ritzenhofen proposed the implicit factorization problem (IFP). They showed that it is undemanding to factor two h-bit RSA moduli N1=p1q1, N2=p2q2 where q1, q2 are both αh-bit, and p1, p2 share uh&gt;2αh the least significant bits (LSBs). Subsequent works mainly focused on extending the IFP to the cases where p1, p2 share some of the most significant bits (MSBs) or the middle bits (MBs). In this paper, we propose a novel generalized IFP where p1 and p2 share an arbitrary number of bit blocks, with each block having a consistent displacement in its position between p1 and p2, and we solve it successfully based on Coppersmith’s method. Specifically, we generate a new set of shift polynomials to construct the lattice and optimize the structure of the lattice by introducing a new variable z=p1. We derive that we can factor the two moduli in polynomial time when u&gt;2(n+1)α(1−α^1/(n+1)) with p1, p2 sharing n blocks. Further, no matter how many blocks are shared, we can theoretically factor the two moduli as long as u&gt;2αln(1/α). In addition, we consider two other cases where the positions of the shared blocks are arbitrary or there are k&gt;2 known moduli. Meanwhile, we provide the corresponding solutions for the two cases. Our work is verified by experiments. </p

The Core and Accessory Genomes of Burkholderia pseudomallei: Implications for Human Melioidosis

Natural isolates of Burkholderia pseudomallei (Bp), the causative agent of melioidosis, can exhibit significant ecological flexibility that is likely reflective of a dynamic genome. Using whole-genome Bp microarrays, we examined patterns of gene presence and absence across 94 South East Asian strains isolated from a variety of clinical, environmental, or animal sources. 86% of the Bp K96243 reference genome was common to all the strains representing the Bp “core genome”, comprising genes largely involved in essential functions (eg amino acid metabolism, protein translation). In contrast, 14% of the K96243 genome was variably present across the isolates. This Bp accessory genome encompassed multiple genomic islands (GIs), paralogous genes, and insertions/deletions, including three distinct lipopolysaccharide (LPS)-related gene clusters. Strikingly, strains recovered from cases of human melioidosis clustered on a tree based on accessory gene content, and were significantly more likely to harbor certain GIs compared to animal and environmental isolates. Consistent with the inference that the GIs may contribute to pathogenesis, experimental mutation of BPSS2053, a GI gene, reduced microbial adherence to human epithelial cells. Our results suggest that the Bp accessory genome is likely to play an important role in microbial adaptation and virulence

Short-term effects of thinning on the understory natural environment of mixed broadleaf-conifer forest in Changbai Mountain area, Northeast China

Background The understory natural environment is critical in affecting the succession and recovery process of vegetation, stand structure, and species composition of forest. The thinning intensity could significantly change the forest microclimates and soil properties, therefore, to analyze the effects of thinning intensity on the understory natural environment of forest is of important significance for promoting the ecological benefits of thinning. Methods A total of 16 fixed sample plots with different thinning intensities were established in the mixed broadleaf-conifer forest in Jiaohe, situated in Changbai Mountain area, Northeast China, and the forest microclimates and soil properties were investigated after 4 years since the establishment of the sample plots. Results The results showed that the high intensity thinning significantly decreased the leaf area index from 4.13 (unthinned plot) to 2.21 (high intensity thinned plot), and the air temperature was increased by thinning from May to July. Comparing with the unthinned plot, thinning caused a rise of temperature (ranging from 2.11 to 6.74 °C, depending on the intensity of thinning) in May. However, it showed cooling effect in September and October. Besides, the air moisture of thinning plots was lower than the control plot in May and October, when the density of leaves is lower in the forest, and it even decreased 20.27% after thinning. The thinning intensity had no significantly effect on water content and organic carbon in forest soils, and only the bulk density in the top-layer soils in high intensity thinning plot was remarkably increased. Total nitrogen in soil was increased by different intensities of thinning, and the availability of nutrients for nitrogen, phosphorus and potassium in some soils were also affected

Short-term effects of thinning on the understory natural environment of mixed broadleaf-conifer forest in Changbai Mountain area, Northeast China

Background The understory natural environment is critical in affecting the succession and recovery process of vegetation, stand structure, and species composition of forest. The thinning intensity could significantly change the forest microclimates and soil properties, therefore, to analyze the effects of thinning intensity on the understory natural environment of forest is of important significance for promoting the ecological benefits of thinning. Methods A total of 16 fixed sample plots with different thinning intensities were established in the mixed broadleaf-conifer forest in Jiaohe, situated in Changbai Mountain area, Northeast China, and the forest microclimates and soil properties were investigated after 4 years since the establishment of the sample plots. Results The results showed that the high intensity thinning significantly decreased the leaf area index from 4.13 (unthinned plot) to 2.21 (high intensity thinned plot), and the air temperature was increased by thinning from May to July. Comparing with the unthinned plot, thinning caused a rise of temperature (ranging from 2.11 to 6.74 °C, depending on the intensity of thinning) in May. However, it showed cooling effect in September and October. Besides, the air moisture of thinning plots was lower than the control plot in May and October, when the density of leaves is lower in the forest, and it even decreased 20.27% after thinning. The thinning intensity had no significantly effect on water content and organic carbon in forest soils, and only the bulk density in the top-layer soils in high intensity thinning plot was remarkably increased. Total nitrogen in soil was increased by different intensities of thinning, and the availability of nutrients for nitrogen, phosphorus and potassium in some soils were also affected. </jats:sec