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Public Key Cryptosystem (PKC) completely relies under the assumption that user’s private key is absolutely secure. Exposure of private key may lead to disastrous situations in the communication network. To diminish the damage of private key exposure in PKC, key-insulation mechanism was introduced. In key-insulated cryptosystems, a user can update his private key with the help of a physically secure device from time to time. Identity-based cryptosystem alleviates the heavy certificate management problems in traditional PKC. Recently, many Identity-based key insulated signature schemes have been proposed in literature; however, most of the Identity-based schemes are designed based on the expensive bilinear pairing operation over elliptic curves. Due to the heavy computational cost of a pairing, the pairing based schemes are less efficient in practice. In order to improve the computational and communicational efficiency and to resist the problem of private key exposure in Identity-based signature schemes, we present a pairing-free key insulated signature scheme in identity based setting. We show that this scheme is unforgeable and achieves strong key insulation property with secure key updates, under the hardness of the Elliptic Curve Discrete Logarithm Problem (ECDLP). The performance analysis shows that our scheme is more efficient than the existing schemes.

In recent years, IoT has opened new opportunities for the development of various industries to improve people’s lives. Vehicular ad hoc network (VANET) uses IoT applications for secure communication among the vehicles and to improve road safety and traffic management. In VANETS, the authentication of the vehicular access control is a crucial security service for both intervehicle and vehicle–roadside unit communications. Another criteria is all the messages should be unaltered in the delivery. Meanwhile, vehicles have to be prevented from the misuse of private information and the attacks on their privacy. Also, limited bandwidth, high mobility and density of vehicles, and scalability are few other challenges in VANETS. A number of research works are focusing on providing the anonymous authentication with preserved privacy and security in VANETS. In this article, we proposed a new certificateless aggregate signature-based authentication scheme for VANETS. Our scheme avoids the complex certificate management problem from public-key infrastructure and key escrow problem from an identity-based framework. Also, aggregate signature aggregates various individual signatures on different messages from different vehicles into a single signature, which in turn results in the reduction of verification time and storage space at the roadside unit. Our scheme can prevent malicious vehicles from disrupting the security features of VANETS. Moreover, our scheme does not use the pairing operation, which is the most expensive operation than others in modern cryptography, thus significantly reduces the computation overhead. Security and performance analysis shows that our scheme is more secure and efficient than current schemes.

In many real-world situations, signature schemes with message recovery plays a very important role to minimize the bandwidth for efficient communications. A proxy signature scheme is a kind of digital signature scheme that allows an original signer to designate his/her signing capacity to a proxy signer. The proxy signer generates a signature on a message on behalf of the original signer. Such signatures are very useful in various applications where the delegation rights is quite common, especially in distributed systems and grid computing. This paper presents a pairing-free proxy signature with message recovery scheme that integrates the advantages of proxy signatures and message recovery in identity based setting. This scheme improves the computational and communicational efficiency due to pairing-free and message recovery features. The proposed scheme is proven secure in the random oracle model under the hardness assumption of the ECDLP. The comparison results shows that the proposed scheme is superior to the related works from the aspect of security and performance.

With the development of wireless communication technology, many network systems are interconnected with large number of smart devices and internet to gather and share electronic data. Due to its open nature, the data transmitted over public networks. Thus ensuring privacy and data security are of great importance. Also computing power, storage and bandwidth requirements are the main constraints in the development of many applications. To resolve these security and efficiency issues, this letter presents an efficient pairing free certificateless signature scheme. This scheme is proven secure and unforgeable. Finally, the comparative analysis shows the efficiency of our scheme.

The most important contribution of modern cryptography is the invention of digital signatures. To deal with specific application scenarios, digital signature schemes have been evolved with ...

Automatic dependent surveillance-broadcast (ADS-B) is an emerging air traffic surveillance technology that overcomes the limitations of today's radar technology and enhances the air traffic control. To provide authenticity, integrity in ADS-B and to improve the computation, communications efficiency, in this paper, we propose a new, efficient, and secure pairing-free ADS-B authentication scheme with Batch Verification in ID-based framework. The proposed scheme is proven secure and is more efficient than the existing schemes.

Recent advancements in wireless communication technologies have led to the development of practical applications, such as infrastructure monitoring, earthquake monitoring, environment monitoring, remote healthcare monitoring, etc. In these applications, we may integrate the wireless sensor networks (WSNs) with Internet of Things (IoT), where sensor nodes join the Internet dynamically and use it to collaborate and accomplish their tasks. In e-healthcare system, wireless medical sensor nodes continuously monitor and collect the physiological information and transmit the same to healthcare professionals through IoT terminals. To overcome the limitations in communication and computational capabilities in sensors and to attain privacy in healthcare wireless medical sensor networks (HWMSNs), few signature schemes were proposed in the literature. However, most of these schemes are insecure against various attacks. Hence to ensure privacy and security in medical data, in this paper, we proposed an efficient pairing-free aggregate signature scheme for HWMSNs in certificateless system. We exploit aggregation technique in certificateless system without using pairings to reduce computational complexity and transmission overhead in transferring the data. Our scheme achieves full aggregation to improve communicational efficiency and performance analysis shows that the proposed scheme is more efficient.

The continuous progress of the wireless communication technology provides an intelligent and efficient transportation system through vehicular ad-hoc networks (VANETS) to mitigate traffic jams and road fatalities, which improves safety of passengers and traffic flow. Many researchers, vehicle manufacturers, and telecommunication industries are working on VANETS to construct the next generation transport system. In VANETS, vehicles, equipped with wireless devices, exchange the traffic-related information with other vehicles and the fixed road side units (RSUs). The information shared between vehicles and RSUs in VANETS must be secure. For secure communications in VANETS, many cryptographic schemes were proposed in different settings, and most of the schemes are using bilinear pairings over elliptic curves. But the computation of a bilinear pairing is very expensive. Also the verification of signatures/messages sent by vehicles increases the computational workload on RSUs. In order to improve computational efficiency and transmission overhead, in this paper, we present an efficient pairing-free certificateless authentication scheme with batch verification for VANETS. We designed the scheme in pairing-free environment which improves the communication and computational efficiency. The proposed scheme supports batch verification, which significantly reduces the computational workload on RSUs in VANETS. The proposed scheme is proven secure in the random oracle model and meets the security requirements, such as authenticity, integrity, traceability, anonymity, and revocation. We compared our scheme with well-known existing schemes, and the efficiency analysis shows that the proposed scheme is more efficient.

Private key exposure can be the most devastating attack on cryptographic schemes; as such exposure leads to the breakage of security of the scheme as a whole. In the real world scenario, this problem is perhaps the biggest threat to cryptography. The threat is increasing with users operating on low computational devices (e.g. mobile devices) which hold the corresponding private key for generating signatures. To reduce the damage caused by the key exposure problem in aggregate signatures and preserve the benefits of identity-based (ID-based) cryptography, we hereby propose the first key-insulated aggregate signature scheme in ID-based setting. In this scheme the leakage of temporary private keys will not compromise the security of all the remaining time periods. The security of our scheme is proven secure in the random oracle paradigm with the assumption that the Computational Diffie–Hellman (CDH) problem is intractable. The proposed scheme allows an efficient verification with constant signature size, independent of the number of signers.

AimTo examine the relationship between plasma levels of N-terminal-proB type natriuretic peptide (NT-proBNP) and various echocardiographic and hemodynamic parameters in patients with mitral stenosis undergoing percutaneous transvenous mitral commissurotomy (PTMC).Materials and methodsThe study population consisted of 100 patients with rheumatic mitral stenosis who underwent PTMC. NT-proBNP levels in these patients were measured before PTMC and 48hours after PTMC. These levels were then correlated with various echocardiographic and hemodynamic parameters measured before and after PTMC.ResultsEighty-one percent of the study population were women, and the most common presenting symptom was dyspnea which was present in 94% of the patients. Dyspnea New York Heart Association class correlated significantly with baseline NT-proBNP levels (r=0.63; p

Key insulated mechanism mitigates the potential damages caused by secret signing key exposure in public key signature schemes. To minimize the impact of secret key exposure in group-oriented applications, in this paper, we propose a novel Pairing-free Identity-based Key-insulated Multi Signature (PF-IDKIMS) scheme. The strong key insulated security of our PF-IDKIMS primitive is reduced to the classical elliptic curve discrete logarithm problem in random oracle model. To the best of our knowledge, the proposed scheme is the first multi signature scheme without pairings in identity based framework dealing with key exposure problems by employing key insulation mechanism.

Exposure of private keys in cryptographic schemes leads to breakage of security of the scheme as a whole. To avoid the damage caused by key exposure problem, in this paper, we propose an efficient ID-Based Key-insulated Signature (IBKIS) scheme with batch verifications using bilinear pairings over elliptic curves. This scheme updates the signer's private keys from time to time. The proposed scheme is secure in the random oracle model with the assumption that the CDH problem is intractable. We compare the proposed scheme with related schemes.

This paper deals with the optimization of phase jump angle of series active power filter by using particle swarm optimization technique and series active power filter compensates supply voltage distortions/unbalance, supply voltage harmonics in a view as such they do not reach at the load end with very low THD in load voltage. SAPF operates mainly as voltage regulator and harmonic isolator between the non-linear load and the utility system. The main aim of this project is to design the dynamic model of the Series Active Power Filter and minimization of VA rating of the Series Active Power Filter by using practical swarm optimization (PSO). Hence the results are obtained by using the Matlab/Simulink.

Cryptography algorithms provide confidentiality, integrity and authentication of communication channels. These algorithms and protocols are based on sophisticated mathe-matics such as computational and algorithmic algebraic geometry, coding theory, and generic algorithms for finite abelian groups. For secure encryption, establishing or transferring a shared key between the parties is an interesting challenge. Key management is an essential crypto-graphic primitive upon which other security primitives are built. In this paper, we present a generic construction of asymmetric key Group key transfer protocol using one way function and coding theory technique. By guaranteeing the freshness of authentication messages, the authenticity of the generator of authentication messages and the completeness of the authenticator, the improved protocol can resist various passive and active attacks. The protocol allows the participants in the group to derive a common encryption key, provide the key security and unknown key share properties. Security analysis of proposed scheme is also discussed.

Signcryption is a cryptographic primitive that provides the functionalities of digital signature and public key encryption simultaneously, at a lower computational costs and communication overheads than the traditional signature-then-encryption approach. In some applications, it is often required that multiple senders have to send a message in a secure and authenticated way. If signcryptions are performed individually by the group of senders, the cost involved in unsigncryption is high. So that it is not an efficient way to signcrypt the message separately. An efficient alternative method is multi-signcryption. In this paper, we propose an efficient identity based multi-signcryption scheme with public verifiability. This scheme provides the functionalities of both multi signatures and secure encryption for multiple senders; and these schemes enables to perform unsigncryption with the cost equal to a single unsigncryption irrespective of the number of senders. We discuss the security requirements s...

Nowadays electronic communication is ubiquitous, irreplaceable; Digital signature plays an essential role in these secure communications. Digital signatures have expanded rapidly along with mathematical advances in lattices, pairings and elliptic curves. Due to their high efficiency and strong security properties, the elliptic curve cryptographic schemes remain the best option for many security goals. Pairing free signature schemes on elliptic curves is an emerging area of interest for efficient community. To deal with specific application scenarios, digital signature schemes have evolved into many variants. One of such variant is Directed signature scheme. A directed signature is a kind of signature where the verification ability is controlled by the signer. Here the validity of the signature can be verified by a designated verifier only and nobody knows anything about the verifier. Directed signature schemes are suitable for applications where message is sensitive to recipient; for example bill of tax and health. In this paper we propose an efficient and secure pairing free Identity (ID) based directed signature (IDBDS) scheme over elliptic curves. To the best of our knowledge, this is the first scheme in ID based setting addressing about directedness in pairing free environment. We prove its security using random oracle model under the assumption that the Elliptic Curve Discrete Logarithm Problem (ECDLP) is hard. We compare our scheme with well known existing schemes and efficiency analysis shows that our scheme is more efficient than all other related schemes.

Due to the limited computational resources and communicational bandwidth in wireless communication systems, Certificateless Public key Cryptography came into light and reduced a significant amount of data load on the network. Certificateless cryptographic schemes not only eliminate the certificate management complexities in the traditional Public Key Cryptography (PKC) but also resolve the key escrow problem, which is a major drawback in identity based PKC. This paper proposes a new certificateless signature scheme with formal security proof using pairings. It improves the computational and communicational efficiency along with security against the known adversaries.

In view of simplifying certificate management complexities in the traditional Public Key Cryptography (PKC) and to abolish the key escrow problem in identity based PKC (ID-PKC), concept of Certificateless Public Key Cryptography (CL-PKC) was introduced. Batch Cryptography emphasizes new developments in information security and communication networks. It has been developed to enhance the efficiency of signatures verification, by verifying a batch of n message, signature pairs in a single instance. Batch Verification (BV) can be used in various areas where many clients interact with a single server. Mail servers, Sensor Networks, e-commerce are the best examples for BV. In this paper, we present a certificateless signature (CLS) scheme that supports BV using pairings. The proof of security is presented in Random Oracle Model (ROM) under the assumption of Computational Diffie-Hellman (CDH) Problem is intractable. More over the security proofs are made without using forking lemma [20] to achieve tight security. The efficiency analysis shows that our CLS scheme is more secure and efficient than the existing schemes.

This paper deals with a design of a hysteresis voltage control based inter line dynamic voltage restorer (IDVR) in three phase system under different considerations and the proposed inter line DVR to improve power quality in parallel feeder distribution system with help of multi converts. The IDVR has to inject the required volt ampere power into faulty feeder system in order to regulate the load voltages. It desirable to optimize the VA rating with optimal phase jump angle. The proposed method was able to compensate voltage sag and unbalanced voltages with optimal phase jump angle by using IDVR and with minimum VA rating. Minimum VA rating and optimal phase jump angle computed by particle swarm optimization technique and computed values compare the genetic algorithim technique.

An ID-based cryptographic scheme enables the user to public keys without exchanging public key certificates. In these schemes, users can generate their public and private keys using their identity. The positive application of bilinear pairings over elliptic curves makes the system easy and efficient in providing security. In this paper, we propose an ID-based signature scheme using bilinear pairings. We prove that the proposed signature scheme is secure against existential forgery under adaptively chosen message and ID attack in the random oracle model with the assumption that the computational Diffie-Hellman problem is intractable. We compare the efficiency of the proposed scheme with some related ID-based signature schemes.

A dry chemistry system for rapid qualitative measurement of cardiac troponin T in whole blood, serum, EDTA and lithium heparin plasma was studied in 197 admissions to the coronary care unit and general wards of a typical district general hospital for whom troponin T was requested. This included patients with unexplained collapse, acute dysrythmia or elevated creatine kinase of unknown origin. EDTA whole blood and plasma proved the most satisfactory sample matrices. Lithium heparin whole blood was equally appropriate but lithium heparin plasma gave a false negative result. Serum was an unsatisfactory sample material. Comparison with the conventional wet chemistry quantitative enzyme-linked immunosorbent assay showed a positive bias for EDTA plasma, particularly in the range 0–1 μg/L and a significant negative bias for lithium heparin plasma. There was no difference between serum from plain or gel separator tubes. The whole blood method allows troponin T measurement to be performed rapidly and simply in the laboratory, either as an emergency test to alter patient management, or for those laboratories that wish to offer troponin T for selected cases but do not have the ability to measure troponin T quantitatively.

This paper deals with a new design dynamic model of synchronous-reference- frame (SRF)-based control in three phase system under different load considerations to improve power quality by using power conditioner with multi converters. The proposed MCUPQC system can regulate the load voltages/bus voltages on Parallel power distribution systems under balanced and distorted load conditions and obtain the state space model for MC-UPQC. The simulation results to support the SRF-based control method presented in this paper is done using Matlab/Simulink.

Signcryption is a cryptographic primitive that performs encryption and signature in a single logical step, at lower computational cost and communication over heads than the signature-then-encryption. Proxy signcryption schemes are variations of ordinary signcryption schemes and have been useful in many applications where the delegation of rights is quite common. By combining the functionalities of proxy signature scheme and signcryption scheme, in this paper, we proposed a new ID-based proxy signcryption scheme which offers both public verifiability and forward security. The security requirements and performance of the proposed scheme are analyzed.

This paper presents a new voltage regulation system multi converter dynamic voltage restorer (MC-DVR), capable of simultaneous compensation for voltage in Multibus/multifeeder systems. In this configuration two voltage-source converters (VSC) exist. The system can be applied to adjacent feeders to compensate for supply-voltage on the main feeder and full compensation of supply-voltage imperfections on the other feeders. In the proposed configuration, all converters are connected back to back on the dc side and share a common dc-link capacitor. Therefore, power can be transferred from one feeder to adjacent feeders to compensate for sag. The performance of the MC-DVR as well as the adopted control algorithm is illustrated by simulation. The results obtained in MATLAB/SIMULINK on a two-bus/two-feeder system show the effectiveness of the proposed configuration.

Two storey bilinear hysteretic structures have been studied with a view to exploring the possibility of using the dynamic vibration absorber concept in earthquake-resistant design. The response of the lower storey has been optimized for the Taft 1952, S69°E accelerogram with reference to parameters such as frequency ratio, yield strength ratio and mass ratio. The influence of viscous damping has also been examined.

Limit state designs are being applied to an increasingly wide range of reinforced concrete structures. For complex forms such as shear walls, eccentrically stiffened slabs and box beams, current design methods are usually derived from elastic theories. Behaviour of slab assemblages in the post-cracking range has not been widely studied. This work investigates the suitability of the finite element method to analyse such structures monotonically loaded to failure. A simple behavioural model for reinforced concrete is proposed and, in conjunction with a constant stiffness approach, a non-linear procedure is derived. Results obtained from the approach are compared with experimental evidence from tests on slabs, deep beams, t beams and box beams. From this evidence conclusions are drawn regarding the suitability of the method to predict the behaviour of concrete structures over the entire loading range.(a) /TRRL/

This paper deals with a design of optimal parameters of PI regulator in voltage control loop. The design aims to minimize voltampere (VA) loading of synchronous reference frame (SRF) based multi converter-DVR in parallel feeder distribution systems. To improve the power quality by using power conditioner with multi converters in each feeder distribution system under different load considerations, a dynamic model of synchronous-reference- frame (SRF) has been adopted. It is desirable to have optimization of PI components and generate the reference compensate voltages for series active filters (SAF) of MC-DVR. Therefore, series active filters help to inject optimal voltages at optimal angle in such a way that a minimum VA loading of MCDVR is possible. The optimal value PI components and optimal series injected angle of series active power filters are computed using particle swarm optimization (PSO) technique and the results are verified with genetic algorithm (GA). The simulation results show that the proposed PSO technique causes minimum error and minimum VA loading angle by optimally choosing parameters of PI and minimum VA angle as compared to GA technique.Keywords: Active power filter (APF), synchronous reference frame (SRF), Genetic algorithm (GA), Particle Swarm Optimization (PSO) and multi converter dynamic voltage restorer (MC-DVR).

Signcryption is a cryptographic primitive that performs both encryption and signature in a single logical step more efficiently than sign-then-encryption approach. Till now various kinds of signcryption schemes have been proposed. In this paper we propose a new identity based multi-proxy multi signcryption scheme from bilinear pairings, which is both public verifiable and forward secure. This scheme is a combination of multi-proxy multi-signature scheme with signcryption scheme. We discuss the security requirements of our new scheme. Finally, we compare our scheme with previous schemes in computational point of view.