A Secure and Efficient Authentication Protocol (SEAP) for MANETs with Membership Revocation

In this paper, we propose a novel authentication protocol for MANETs requiring stronger security. The protocol works on a two-tier network architecture with client nodes and authentication server nodes, and supports dynamic membership. We use an external membership granting server (MGS) to provide stronger security with dynamic membership. However, the external MGS in our protocol is semi-online instead of being online, i.e., the MGS cannot initiate a connection with a network node but any network node can communicate with the MGS whenever required. To ensure efficiency, the protocol uses symmetric key cryptography to implement the authentication service. However, to achieve storage scalability, the protocol uses a pseudo random function (PRF) to bind the secret key of a client to its identity using the secret key of its server. In addition, the protocol possesses an efficient server revocation mechanism along with an efficient server re-assignment mechanism, which makes the protocol robust against server node compromise.

A Protocol for Authentication with Multiple Levels of Anonymity (AMLA) in VANETs

The basic requirements for secure communication in a vehicular ad hoc network (VANET) are anonymous authentication with source non-repudiation and integrity. The existing security protocols in VANETs do not differentiate between the anonymity requirements of different vehicles and the level of anonymity provided by these protocols is the same for all the vehicles in a network. To provide high level of anonymity, the resource requirements of security protocol would also be high. Hence, in a resource constrained VANET, it is necessary to differentiate between the anonymity requirements of different vehicles and to provide the level of anonymity to a vehicle as per its requirement. In this paper, we have proposed a novel protocol for authentication which can provide multiple levels of anonymity in VANETs. The protocol makes use of identity based signature mechanism and pseudonyms to implement anonymous authentication with source non-repudiation and integrity. By controlling the number of pseudonyms issued to a vehicle and the lifetime of each pseudonym for a vehicle, the protocol is able to control the level of anonymity provided to a vehicle. In addition, the protocol includes a novel pseudonym issuance policy using which the protocol can ensure the uniqueness of a newly generated pseudonym by checking only a very small subset of the set of pseudonyms previously issued to all the vehicles. The protocol cryptographically binds an expiry date to each pseudonym, and in this way, enforces an implicit revocation for the pseudonyms. Analytical and simulation results confirm the effectiveness of the proposed protocol.

De novo inference of protein function from coarse-grained dynamics

Inference of molecular function of proteins is the fundamental task in the quest for understanding cellular processes. The task is getting increasingly difficult with thousands of new proteins discovered each day. The difficulty arises primarily due to lack of high-throughput experimental technique for assessing protein molecular function, a lacunae that computational approaches are trying hard to fill. The latter too faces a major bottleneck in absence of clear evidence based on evolutionary information. Here we propose a de novo approach to annotate protein molecular function through structural dynamics match for a pair of segments from two dissimilar proteins, which may share even <10% sequence identity. To screen these matches, corresponding 1 mu s coarse-grained (CG) molecular dynamics trajectories were used to compute normalized root-mean-square-fluctuation graphs and select mobile segments, which were, thereafter, matched for all pairs using unweighted three-dimensional autocorrelation vectors. Our in-house custom-built forcefield (FF), extensively validated against dynamics information obtained from experimental nuclear magnetic resonance data, was specifically used to generate the CG dynamics trajectories. The test for correspondence of dynamics-signature of protein segments and function revealed 87% true positive rate and 93.5% true negative rate, on a dataset of 60 experimentally validated proteins, including moonlighting proteins and those with novel functional motifs. A random test against 315 unique fold/function proteins for a negative test gave >99% true recall. A blind prediction on a novel protein appears consistent with additional evidences retrieved therein. This is the first proof-of-principle of generalized use of structural dynamics for inferring protein molecular function leveraging our custom-made CG FF, useful to all. (C) 2014 Wiley Periodicals, Inc.

Development of a global inundation map at high spatial resolution from topographic downscaling of coarse-scale remote sensing data

Large-scale estimates of the area of terrestrial surface waters have greatly improved over time, in particular through the development of multi-satellite methodologies, but the generally coarse spatial resolution (tens of kms) of global observations is still inadequate for many ecological applications. The goal of this study is to introduce a new, globally applicable downscaling method and to demonstrate its applicability to derive fine resolution results from coarse global inundation estimates. The downscaling procedure predicts the location of surface water cover with an inundation probability map that was generated by bagged derision trees using globally available topographic and hydrographic information from the SRTM-derived HydroSHEDS database and trained on the wetland extent of the GLC2000 global land cover map. We applied the downscaling technique to the Global Inundation Extent from Multi-Satellites (GIEMS) dataset to produce a new high-resolution inundation map at a pixel size of 15 arc-seconds, termed GIEMS-D15. GIEMS-D15 represents three states of land surface inundation extents: mean annual minimum (total area, 6.5 x 10(6) km(2)), mean annual maximum (12.1 x 10(6) km(2)), and long-term maximum (173 x 10(6) km(2)); the latter depicts the largest surface water area of any global map to date. While the accuracy of GIEMS-D15 reflects distribution errors introduced by the downscaling process as well as errors from the original satellite estimates, overall accuracy is good yet spatially variable. A comparison against regional wetland cover maps generated by independent observations shows that the results adequately represent large floodplains and wetlands. GIEMS-D15 offers a higher resolution delineation of inundated areas than previously available for the assessment of global freshwater resources and the study of large floodplain and wetland ecosystems. The technique of applying inundation probabilities also allows for coupling with coarse-scale hydro-climatological model simulations. (C) 2014 Elsevier Inc All rights reserved.

Anonymous Authentication with Shared Secrets

Anonymity and authenticity are both important yet often conflicting security goals in a wide range of applications. On the one hand for many applications (say for access control) it is crucial to be able to verify the identity of a given legitimate party (a.k.a. entity authentication). Alternatively an application might require that no one but a party can communicate on its behalf (a.k.a. message authentication). Yet, on the other hand privacy concerns also dictate that anonymity of a legitimate party should be preserved; that is no information concerning the identity of parties should be leaked to an outside entity eavesdropping on the communication. This conflict becomes even more acute when considering anonymity with respect to an active entity that may attempt to impersonate other parties in the system. In this work we resolve this conflict in two steps. First we formalize what it means for a system to provide both authenticity and anonymity even in the presence of an active man-in-the-middle adversary for various specific applications such as message and entity authentication using the constructive cryptography framework of Mau11, MR11]. Our approach inherits the composability statement of constructive cryptography and can therefore be directly used in any higher-level context. Next we demonstrate several simple protocols for realizing these systems, at times relying on a new type of (probabilistic) Message Authentication Code (MAC) called key indistinguishable (KI) MACs. Similar to the key hiding encryption schemes of BBDP01] they guarantee that tags leak no discernible information about the keys used to generate them.

Coarse-to-fine vision-based localization by indexing scale-invariant features

This paper presents a novel coarse-to-fine global localization approach inspired by object recognition and text retrieval techniques. Harris-Laplace interest points characterized by scale-invariant transformation feature descriptors are used as natural landmarks. They are indexed into two databases: a location vector space model (LVSM) and a location database. The localization process consists of two stages: coarse localization and fine localization. Coarse localization from the LVSM is fast, but not accurate enough, whereas localization from the location database using a voting algorithm is relatively slow, but more accurate. The integration of coarse and fine stages makes fast and reliable localization possible. If necessary, the localization result can be verified by epipolar geometry between the representative view in the database and the view to be localized. In addition, the localization system recovers the position of the camera by essential matrix decomposition. The localization system has been tested in indoor and outdoor environments. The results show that our approach is efficient and reliable. © 2006 IEEE.

An algorithm for coarse particle sedimentation simulation by Stokesian dynamics

Coarse Particle sedimentation is studied by using an algorithm with no adjustable parameters based on stokesian dynamics. Only inter-particle interactions of hydrodynamic force and gravity are considered. The sedimentation of a simple cubic array of spheres is used to verify the computational results. The scaling and parallelism with OpenMP of the method are presented. Random suspension sedimentation is investigated with Mont Carlo simulation. The computational results are shown in good agreement with experimental fitting at the lower computational cost of O(N In N).

Multi-scale Calculation of Settling Speed of Coarse Particles by Accelerated Stokesian Dynamics without Adjustable Parameter

The calculation of settling speed of coarse particles is firstly addressed, with accelerated Stokesian dynamics without adjustable parameters, in which far field force acting on the particle instead of particle velocity is chosen as dependent variables to consider inter-particle hydrodynamic interactions. The sedimentation of a simple cubic array of spherical particles is simulated and compared to the results available to verify and validate the numerical code and computational scheme. The improvedmethod keeps the same computational cost of the order O(N log N) as usual accelerated Stokesian dynamics does. Then, more realistic random suspension sedimentation is investigated with the help ofMont Carlo method. The computational results agree well with experimental fitting. Finally, the sedimentation of finer cohesive particle, which is often observed in estuary environment, is presented as a further application in coastal engineering.

Coarse fish in Scotland: a threat or a resource?

This brief article summarizes the ecological role of non-salmonid fishes in Scottish fresh waters. Most government-sponsored research has focused on the ecologically valuable salmonids in this area, yet non-salmonid species are widely distributed in Scotland and play an important ecological role in freshwater ecosystems. The fish fauna of Scotland differs from other parts of the British Isles by being more impoverished following the end of the last Ice Age, ca. 10 000 years ago.

An annotated bibliography of research on coarse and salmonid fish (excluding salmon and trout) found in fresh water in Scotland

The authors provide an extensive annotated bibliography to a full list of species occurring in Scotland, to highlight what is known about them and to indicate potential areas for further research. The list of references brings together published research papers and numerous unpublished theses and reports, including experimental and laboratory studies conducted in Scotland, although some may not have unique application to the fish fauna in Scottish waters. There has been no attempt to include references that are made incidentally in the general literature intended for naturalists.