Abstract

We consider a generalization of the Standard Model whose action displays conformal invariance in d dimensions. The model contains a strongly coupled dark matter sector which breaks conformal symmetry dynamically. The model evades conformal anomaly and leads to identically zero vacuum energy in flat space-time. Hence it does not suffer from the problem of fine tuning of the cosmological constant. We determine the contribution of non-relativistic matter to the energy-momentum tensor and determine a parameter regime in which it approximately reduces to the standard result. We show how dark energy and dark matter arises in this model. We discuss the parameter range for which the model reduces to the ΛCDM model and hence is consistent with observations.

Abstract

We present the scalar leptoquark pair production process at the LHC computed at the next-to-leading order in QCD, matched to the Pythia parton shower using the MC@ NLO formalism. We consider the leading order decay of a leptoquark to a lepton (e, μ, τ or ν e, ν μ, ν τ) and a jet and observe the effects of parton shower on the final states. For demonstration, we display the kinametical distributions of a selection of observables along with their scale uncertainties for the 13 TeV LHC. We also present pair production cross sections and K-factors using a massless five-quark flavor scheme for different LHC center-of-mass energies. The complete stand-alone code is available online.

Abstract

Quark-lepton compositeness is a well-known beyond the Standard Model (SM) scenario with heavy exotic particles like leptoquarks (LQs) and leptogluons (LGs) etc. These particles can couple to leptons and jets simultaneously. In this letter, we use the recent CMS scalar LQ search data in the e e j j and eej channels to probe this scenario. We recast the data in terms of a color octet partner of the SM electron (or a first generation spin-1/2 LG) that couples to an electron and a gluon via a dimension five operator suppressed by the quark–lepton compositeness scale (Λ). By combining different production processes of the color octet electron (e 8) at the LHC, we use the CMS 8 TeV data to obtain a simultaneous bound on Λ and the mass of the e 8 (M e 8). We also study the reach of the 13 TeV LHC to discover the e 8 and interpret the required luminosity in terms of M e 8 and Λ.

Abstract

Several remote user authentication techniques for telecare medicine information system (TMIS) have been proposed in the literature. But most existing techniques have limitations such as vulnerable to various attacks, lack of functionalities, and inefficiency. Recently, Amin and Biswas proposed a three‐factor authentication and key agreement technique for TMIS. But their scheme is inefficient and has several security drawbacks. The attacks such as privileged‐insider, user impersonation, and strong reply attacks are possible on their scheme. It also has flaw in password update phase. In order to overcome drawbacks of their scheme, a new provably secure and efficient three‐factor remote user authentication scheme for TMIS is proposed in this paper. The proposed scheme overcomes all drawbacks of their scheme and also provides additional features such as user unlinkability, user anonymity, efficient password, and biometric update. The rigorous informal and formal security analysis using random oracle models and the mostly acceptable Automated Validation of Internet Security Protocols and Applications tool is also performed. During the experimentation, it has been observed that the proposed scheme is secure against various known attacks that include replay and man‐in‐the‐middle attacks. Furthermore, the analysis of computation and communication cost estimation of the proposed scheme depicts that our scheme is efficient as compared with other related exiting schemes.

Abstract

In 2012, Mun et al. proposed an enhanced secure authentication with key-agreement protocol for roaming service in global mobility networks environment based on elliptic curve cryptography. They claimed that their protocol is efficient and resistant to prominent security attacks. The careful analysis of this study proves that Mun et al.'s protocol is susceptible to several attacks such as replay attack, man-in-middle attack, user impersonation attack, privileged insider attack, denial-ofservice attack, no login phase and imperfect mutual authentication phase. In addition, this study proposes an enhanced lightweight authentication with key-agreement protocol for mobile networks based on elliptic curve cryptography using smart cards. The proposed protocol is lightweight and perfectly suitable for real-time applications as it accomplishes simple one-way hash function, message authentication code and exclusive-OR operation. Furthermore, it achieves all the eminent security properties and is resistant to various possible attacks. The security analysis and comparison section demonstrates that the proposed protocol is robust compared with Mun et al.'s protocol.

Abstract

User authentication in wireless sensor network (WSN) plays a very important role in which a legal registered user is allowed to access the real‐time sensing information from the sensor nodes inside WSN. To allow such access, a user needs to be authenticated by the accessed sensor nodes as well as gateway nodes inside WSNs. Because of resource limitations and vulnerability to physical capture of some sensor nodes by an attacker, design of a secure user authentication in WSN continues to be an important and challenging research area in recent years. In this paper, we propose a new three‐factor user authentication scheme based on the multi‐gateway WSN architecture. Through the widely‐accepted Burrows–Abadi–Needham logic, we prove that our scheme provides the secure mutual authentication. We then present the formal security verification of our proposed scheme using AVISPA tool, which is a powerful validation tool for network security applications, and show that our scheme is secure. In addition, the rigorous informal security analysis shows that our scheme is also secure against possible other known attacks including the sensor node capture attack. Furthermore, we present the additional functionality features that our scheme offers, which are efficient in communication and computation.

Abstract

A novel biometric identity-based digital multi-signature (BIO-IDMS) scheme is put forwarded in this paper. The proposed scheme is constructed with the help of fuzzy extractor and elliptic curve bilinear pairings. Furthermore, we designed the formal model and the security model of the proposed BIO-IDMS scheme. The formal security analysis demonstrates that the forgery of the proposed scheme is infeasible in the random oracle model based on the intractability assumption of the computational Diffie–Hellman (CDH) problem. The proposed scheme outperforms in terms of computational cost compared with other related existing multi-signature schemes.

Abstract

Traditional two party client server authentication protocol may not provide a scalable solution for present network environments where personal and ubiquitous computing technologies are involved as it is now becoming multi-server based. To achieve efficient authorized communication, multi-server based authentication protocols have been designed. The key feature of multi-server based protocols is one time registration. We study the existing multi-server based authentication protocols, and identify that many of the multi-server based authentication protocols involve control server in mutual authentication or trusted server environment is required. The involvement of central authority in mutual authentication may be a bottleneck for large network, and the servers may be semi-trusted. To erase these drawbacks, Wei et al. recently proposed a multi-server based authentication protocol. Their protocol does not require all servers to be trusted and involvement of control server in mutual authentication. Unfortunately, we identify the security vulnerability of Wei et al.'s scheme to insider attack and password guessing attack. Additionally, lack of pre-smart card authentication leads to denial of service attack. To enhance the security of Wei et al.'s protocol, we propose a secure biometric-based authentication scheme for multi-server environment using smart card. We simulate the proposed protocol for the formal security verification using the widely accepted AVISPA (Automated Validation of Internet Security Protocols and Applications) tool to show that our scheme is secure against active and passive attacks. In addition, we prove that our proposed scheme provides mutual authentication using the widely-accepted Burrows–Abadi–Needham (BAN) logic and is also secured against various well known attacks. In addition, our scheme is efficient in terms of computational and communication overheads as compared to Wei et al.'s scheme and other existing related schemes.

Abstract

In recent years, user authentication has emerged as an interesting field of research in wireless sensor networks. Most recently, in 2016, Chang and Le presented a scheme to authenticate the users in wireless sensor network using a password and smart card. They proposed two protocols urn:x-wiley:sec:media:sec1573:sec1573-math-0001 and urn:x-wiley:sec:media:sec1573:sec1573-math-0002. urn:x-wiley:sec:media:sec1573:sec1573-math-0003 is based on exclusive or (XOR) and hash functions, while urn:x-wiley:sec:media:sec1573:sec1573-math-0004 deploys elliptic curve cryptography in addition to the two functions used in urn:x-wiley:sec:media:sec1573:sec1573-math-0005. Although their protocols are efficient, we point out that both urn:x-wiley:sec:media:sec1573:sec1573-math-0006 and urn:x-wiley:sec:media:sec1573:sec1573-math-0007 are vulnerable to session specific temporary information attack and offline password guessing attack, while urn:x-wiley:sec:media:sec1573:sec1573-math-0008 is also vulnerable to session key breach attack. In addition, we show that both the protocols urn:x-wiley:sec:media:sec1573:sec1573-math-0009 and urn:x-wiley:sec:media:sec1573:sec1573-math-0010 are inefficient in authentication and password change phases. To withstand these weaknesses found in their protocols, we aim to design a new authentication and key agreement scheme using elliptic curve cryptography. Rigorous formal security proofs using the broadly accepted, the random oracle models, and the Burrows–Abadi–Needham logic and verification using the well‐known Automated Validation of Internet Security Protocols and Applications tool are preformed on our scheme. The analysis shows that our designed scheme has the ability to resist a number of known attacks comprising those found in both Chang–Le's protocols

Abstract

Cloud computing, the conjoin of many types of computing, has made a great impact on the life of everyone. People from anywhere can access the different cloud-based services by using the Internet. A user, who wants to access some cloud-based service, needs to register himself/herself to an authority (service provider), and after that, he/she can use the service. To access the service, each user needs to authenticate to that particular cloud server. Several user authentication schemes for cloud computing have been presented but mostly have limitations/drawbacks as they are prone to various known attacks, such as privileged insider, user and server impersonation, and strong reply attacks, and they also have lack of functionality features. Moreover, these schemes do not provide efficient password change phase. In order to overcome these drawbacks, we propose a new provably secure biometric-based user authentication and key agreement scheme for cloud computing. The proposed scheme overcomes the weaknesses of the existing schemes and supports extra functionality features including user anonymity and efficient password and biometric update phase for multi-server environment. The careful formal security analysis under standard model and informal security analysis and the simulation results for formal security verification using the most acceptable AVISPA tool show that the proposed scheme is secure against various known possible attacks. The analysis of computation and communication overheads of our scheme depicts its efficiency over other related existing schemes, and thus, the proposed scheme is suitable for the cloud computing environment.