Abstract

Since the conception of the seminal work proposed by Eschenauer and Gligor in 2002, several key predistribution mechanisms have been proposed in the literature in order to establish symmetric secret keys between any two neighbor sensor nodes in wireless sensor networks (WSNs) for secure communication. However, due to lack of prior deployment knowledge, limited resources of sensor nodes and security threats posed in the unattended environment of WSNs, it is always a challenging task to propose a better secure key predistribution scheme apart from existing schemes. In this paper, we aim to propose two new key predistribution schemes based on hashed key chains, which provide secure communication between the sensor nodes with the desired storage and communication overheads. The proposed schemes provide better tradeoff among security, network connectivity, and overheads as compared to those for other existing schemes.

Abstract

Authentication schemes present a user-friendly and scalable mechanism to establish the secure and authorized communication between the remote entities over the insecure public network. Later, several authentication schemes have proposed in the literature. However, most of the existing schemes do not satisfy the desirable attributes, such as resistance against known attacks and user anonymity. In 2012, Chen et al. designed a robust authentication scheme to erase the weaknesses of Sood et al.'s scheme. In 2013, Jiang et al. showed that Chen et al.'s scheme is vulnerable to password guessing attack. Furthermore, Jiang et al. presented an efficient solution to overcome the shortcoming of Chen et al.'s scheme. We demonstrate that Jiang et al.'s scheme does not withstand insider attack, on-line and off-line password guessing attacks, and user impersonation attack. Their scheme also fails to provide user's anonymity. To overcome these drawbacks, we aim to propose an enhanced scheme, which reduces the computation overhead and satisfies all desirable security attributes, while retaining the original merits of Jiang et al.'s scheme. The proposed scheme is also comparable in terms of the communication and computational overheads with Jiang et al.'s scheme and other existing schemes. Furthermore, we simulate the enhanced scheme for the formal security analysis utilizing the widely-accepted AVISPA tool and show that the proposed scheme is resistant against active and passive attacks.

Abstract

Current LHC searches for new colored particles generally focus on their pair production channels and assume any single production to be negligible. We argue that such an assumption may be unnecessary in some cases. Inclusion of model dependent single productions in pair production searches (or vice versa) can give us new information about model parameters or better exclusion limits. Considering the example of the recent CMS search for first generation scalar leptoquarks in the pair production channel, we illustrate how single productions can be systematically included in the signal estimations and demonstrate how it can affect the mass exclusion limits and give new bounds on leptoquark-lepton-quark couplings. We also estimate the effect of the pair production in the more recent CMS search for scalar leptoquarks in single production channels.

Abstract

We study the implications of the ELKO fermions as a cold dark matter candidate. Such fermions arise in theories that are not symmetric under the full Lorentz group. Although they do not carry electric charge, ELKOs can still couple to photons through a nonstandard interaction. They also couple to the Higgs but do not couple to other standard model particles. We impose limits on their coupling strength and the ELKO mass assuming that these particles give dominant contribution to the cosmological cold dark matter. We also determine limits imposed by the direct dark matter search experiments on the ELKO-photon and the ELKO-Higgs coupling. Furthermore we determine the limit imposed by the gamma ray bursts time delay observations on the ELKO-Higgs coupling. We find that astrophysical and cosmological considerations rule out the possibility that ELKO may contribute significantly as a cold dark matter …

Abstract

In the context of a simple five-dimensional (5D) model with bulk matter coupled to a brane-localized Higgs boson, we point out a non-commutativity in the 4D calculation of the mass spectrum for excited fermion towers: the obtained expression depends on the choice in ordering the limits, (infinite Kaluza–Klein tower) and ( being the parameter introduced for regularizing the Higgs Dirac peak). This introduces the question of which one is the correct order; we then show that the two possible orders of regularization (called I and II) are experimentally equivalent, as both can typically reproduce the measured observables, but that the one with less degrees of freedom (I) could be uniquely excluded by future experimental constraints. This conclusion is based on the exact matching between the 4D and 5D analytical calculations of the mass spectrum – via regularizations of type I and II. Beyond a …

Abstract

For critical applications, real‐time data access is essential from the nodes inside a wireless sensor network (WSN). Only the authorized users with unique access privilege should access the specific, but not all, sensing information gathered by the cluster heads in a hierarchical WSNs. Access rights for the correct information and resources for different services from the cluster heads to the genuine users can be provided with the help of efficient user access control mechanisms. In this paper, we propose a new user access control scheme with attribute‐based encryption using elliptic curve cryptography in hierarchical WSNs. In attribute‐based encryption, the ciphertexts are labeled with sets of attributes and secret keys of the users that are associated with their own access structures. The authorized users with the relevant set of attributes can able to decrypt the encrypted message coming from the cluster heads. Our scheme provides high security. Moreover, our scheme is efficient as compared with those for other existing user access control schemes. Through both the formal and informal security analysis, we show that our scheme has the ability to tolerate different known attacks required for a user access control designed for WSNs. Furthermore, we simulate our scheme for the formal security verification using the widely‐accepted automated validation of Internet security protocols and applications tool. The simulation results demonstrate that our scheme is secure.

Abstract

We consider a conformal model involving two real scalar fields in which the conformal symmetry is broken by a soft mechanism and is not anomalous. One of these scalar fields is representative of the standard model Higgs. The model predicts exactly zero cosmological constant. In the simplest version of the model, some of the couplings need to be fine-tuned to very small values. We formulate the problem of fine tuning of these couplings. We argue that the problem arises since we require a soft mechanism to break conformal symmetry. The symmetry breaking is possible only if the scalar fields do not evolve significantly over the time scale of the Universe. Ignoring contributions due to quantum gravity, we present two solutions to this fine tuning problem. We argue that the problem is solved if the classical value of one of the scalar fields is super-Planckian, i.e. takes a value much larger than the Planck mass. The …

Abstract

In communication systems, authentication protocols play an important role in protecting sensitive information against a malicious adversary by means of providing a variety of services such as mutual authentication, user credentials' privacy, and user revocation facility when the smart card of the user is lost/stolen or user's authentication parameters are revealed. Recently, several three‐party authentication with key agreement (3PAKA) schemes are proposed in the literature, but most of them do not provide the basic security requirements such as user anonymity as well as user revocation and re‐registration with the same identity. Thus, we feel that there is a great need to design a secure 3PAKA scheme with these security properties. In this paper, we propose a new secure biometric‐based privacy‐preserving 3PAKA scheme using the elliptic curve cryptography with efficient mechanism for the user revocation and re‐registration with the same identity. The formal security analysis using the widely accepted Burrows–Abadi–Needham logic shows that our scheme provides secure authentication. In addition, we simulate our scheme for the formal security verification using the widely accepted Automated Validation of Internet Security Protocols and Applications tool. The simulation results show that our scheme is secure against passive and active attacks. Furthermore, our scheme is efficient as compared with other related schemes. Our scheme provides high security along with low computation and communication costs, and extra features as compared with other related existing schemes in the literature, and as a result, our scheme is suitable for battery‐limited mobile devices.

Abstract

The energy cost of asymmetric cryptography is a vital component of modern secure communications, which inhibits its wide spread adoption within the ultra-low energy regimes such as Implantable Medical Devices (IMDs) and Radio Frequency Identification (RFID) tags. The ciphertext-policy attribute-based encryption (CP-ABE) is a promising cryptographic tool, where an encryptor can decide the access policy that who can decrypt the data. Thus, the data will be protected from the unauthorized users. However, most of the existing CP-ABE schemes require huge storage and computational overheads. Moreover, CP-ABE schemes based on bilinear map loose the high efficiency over the elliptic curve cryptography because of the requirement of the security parameters of larger size. These drawbacks prevent the use of ultra-low energy devices in practice. In this paper, we aim to propose a novel expressive AND-gate access structured CP-ABE scheme with constant-size secret keys (CSSK) with the cost efficient solutions for the encryption and decryption using ECC, called the CP-ABE-CSSK scheme. In the proposed CP-ABE-CSSK, the size of secret key is as small as 320 bits. In addition, ECC is efficient and more suitable for the lightweight devices as compared to the bilinear pairing based cryptosystem. Thus, the proposed CP-ABE-CSSK scheme provides the low computation and storage overheads with an expressive AND-gate access structure as compared to the related existing schemes in the literature. As a result, our scheme is very suitable for CP-ABE key storage and computation cost in the ultra-low energy devices.

Abstract

In this paper, we devise a new and efficient biometric-based password authentication scheme (BIO-PWA) for the client-server environment. Our scheme uses the elliptic curve cryptography (ECC) along with the fuzzy extractor. Through the rigorous security analysis, we show that our scheme is secure against various known attacks. We further show that our scheme is secure in the generic group model through the formal security analysis. In addition, the formal security verification of our scheme using the widely-accepted automated validation of internet security protocols and applications (AVISPA) tool is performed against active and passive adversaries and the simulation results clearly demonstrate that our scheme is secure against active and passive attacks, including the replay and man-in-the-middle attacks. Finally, we show that our scheme is also efficient in computation against the existing related ECC-based authentication schemes for the client-server environment.