A Generic Construction of Ciphertext-Policy Attribute- Based Encryption Supporting Attribute Revocation

Attribute-based encryption is drawing more attention with its inherent attractive properties which are potential to be widely used in the newly developing cloud computing. However, one of the main obstacles for its application is how to revoke the attributes of the users, though some ABE schemes have realized revocation, they mostly focused on the user revocation that revokes the user＇s whole attributes, or attribute revocation under the indirect revocation model such that all the users＇ private keys will be affected by the revocation. In this paper, we define the model of CP-ABE supporting the attribute revocation under the direct revocation model, in which the revocation list is embed in the ciphertext and none of the users＇ private keys will be affected by the revocation process. Then we propose a generic construction, and prove its security with the decision q-BDHE assumption.

Adaptively Secure Attribute-Based Encryption Supporting Attribute Revocation

Attribute revocation is inevitable and al- so important for Attribute-Based Encryption （ABE） in practice. However, little attention has been paid to this issue, and it retrains one of the rmin obsta-cles for the application of ABE. Most of existing ABE schemes support attribute revocation work under indirect revocation model such that all the users＇ private keys will be affected when the revo-cation events occur. Though some ABE schemes have realized revocation under direct revocation model such that the revocation list is embedded in the ciphertext and none of the users＇ private keys will be affected by revocation, they mostly focused on the user revocation that revokes the user＇s whole attributes, or they can only be proven to be selectively secure. In this paper, we first define a model of adaptively secure ABE supporting the at- tribute revocation under direct revocation model. Then we propose a Key-Policy ABE （KP-ABE） scheme and a Ciphertext-Policy ABE （CP-ABE） scheme on composite order bilinear groups. Finally, we prove our schemes to be adaptively secure by employing the methodology of dual system eno cryption.

FACOR：Flexible Access Control with Outsourceable Revocation in Mobile Clouds

Access control is a key mechanism to secure outsourced data in mobile clouds. Some existing solutions are proposed to enforce flexible access control on outsourced data or reduce the computations performed by mobile devices. However, less attention has been paid to the efficiency of revocation when there are mobile devices needed to be revoked. In this paper, we put forward a new solution, referred to as flexible access control with outsourceable revocation(FACOR) for mobile clouds. The FACOR applies the attribute-based encryption to enable flexible access control on outsourced data, and allows mobile users to outsource the time-consuming encryption and decryption computations to proxies, with only requiring attributes authorization to be fully trusted. As an advantageous feature, FACOR provides an outsourceable revocation for mobile users to reduce the complicated attribute-based revocation operations. The security analysis shows that our FACOR scheme achieves data security against collusion attacks and unauthorized accesses from revoked users. Both theoretical and experimental results confirm that our proposed scheme greatly reliefs the mobile devices from heavy encryption and decryption computations, as well as the complicated revocation of access rights in mobile clouds.

Attribute-Based Access Control Scheme with Efficient Revocation in Cloud Computing

Attribute-based encryption(ABE) supports the fine-grained sharing of encrypted data.In some common designs,attributes are managed by an attribute authority that is supposed to be fully trustworthy.This concept implies that the attribute authority can access all encrypted data,which is known as the key escrow problem.In addition,because all access privileges are defined over a single attribute universe and attributes are shared among multiple data users,the revocation of users is inefficient for the existing ABE scheme.In this paper,we propose a novel scheme that solves the key escrow problem and supports efficient user revocation.First,an access controller is introduced into the existing scheme,and then,secret keys are generated corporately by the attribute authority and access controller.Second,an efficient user revocation mechanism is achieved using a version key that supports forward and backward security.The analysis proves that our scheme is secure and efficient in user authorization and revocation.

AN EFFICIENT FORWARD SECURE GROUP SIGNATURE SCHEME WITH REVOCATION

Up to now, how to construct an efficient secure group signature scheme, which needs not to reset the system when some group members' signing keys are exposed, is still a difficult problem. A construction concerning revocation of group members is an ideal one if it satisfies forward security which makes it more attractive for not sacrificing the security of past signatures of deleted members. This paper analyses the problem and gives a construction in which the group manager can be un-trustworthy. The scheme is efficient even when the number of revoked members is large.

Efficient Membership Revocation in ACJT Group Signature

How to find efficient and secure member- ship revocation algorithms is one of the most important issues standing in the way of real-world applications of group signatures. In this paper, the proof of knowledge of divisibility is given and a novel membership revocation method in ACJT group signature scheme is proposed： the group manager issues the product E of the public keys of current members in the group, when a group member wants to sign, he should not only proves that he has a membership certificate, but also proves that the public key in his certificate divides exactly the public key product E with zero knowledge. The proposed method is efficient since the group manager only needs one division and one exponentiation when a group member is deleted, while the signing and verifying procedure are independent of the number of current group members and excluded members, as well as the original group public key and membership certificates needn＇t be changed.

A Cluster-Based Random Key Revocation Protocol for Wireless Sensor Networks

In recent years,several random key pre-distribution schemes have been proposed to bootstrap keys for encryption,but the problem of key and node revocation has received relatively little attention.In this paper,based on a random key pre-distribution scheme using clustering,we present a novel random key revoca-tion protocol,which is suitable for large scale networks greatly and removes compromised information efficiently.The revocation protocol can guarantee network security by using less memory consumption and communication load,and combined by centralized and distributed revoca-tion,having virtues of timeliness and veracity for revoca-tion at the same time.

An efficient voting based decentralized revocation protocol for vehicular ad hoc networks

Vehicular Ad-hoc NETworks(VANETs)enable cooperative behaviors in vehicular environments and are seen as an integral component of Intelligent Transportation Systems(ITSs).The security of VANETs is crucial for their successful deployment and widespread adoption.A critical aspect of preserving the security and privacy of VANETs is the efficient revocation of the ability of misbehaving or malicious vehicles to participate in the network.This is usually achieved by revoking the validity of the digital certificates of the offending nodes and by maintaining and distributing an accurate Certificate Revocation List(CRL).The immediate revocation of misbehaving vehicles is of prime importance for the safety of other vehicles and users.In this paper,we present a decentralized revocation approach based on Shamir’s secret sharing to revoke misbehaving vehicles with very low delays.Besides enhancing VANETs’security,our proposed protocol limits the size of the revocation list to the number of the revoked vehicles.Consequently,the authentication process is more efficient,and the communication overhead is reduced.We experimentally evaluate our protocol to demonstrate that it provides a reliable solution to the scalability,efficiency and security of VANETs.

Public integrity verification for data sharing in cloud with asynchronous revocation

Cloud data sharing service,which allows a group of people to access and modify the shared data,is one of the most popular and efficient working styles in enterprises.Recently,there is an uprising trend that enterprises tend to move their IT service from local to cloud to ease the management and reduce the cost.Under the new cloud environment,the cloud users require the data integrity verification to inspect the data service at the cloud side.Several recent studies have focused on this application scenario.In these studies,each user within a group is required to sign a data block created or modified by him.While a user is revoked,all the data previously signed by him should be resigned.In the existing research,the resigning process is dependent on the revoked user.However,cloud users are autonomous.They may exit the system at any time without notifying the system admin and even are revoked due to misbehaviors.As the developers in the cloud-based software development platform,they are voluntary and not strictly controlled by the system.Due to this feature,cloud users may not always follow the cloud service protocol.They may not participate in generating the resigning key and may even expose their secret keys after being revoked.If the signature is not resigned in time,the subsequent verification will be affected.And if the secret key is exposed,the shared data will be maliciously modified by the attacker who grasps the key.Therefore,forcing a revoked user to participate in the revocation process will lead to efficiency and security problems.As a result,designing a practical and efficient integrity verification scheme that supports this scenario is highly desirable.In this paper,we identify this challenging problem as the asynchronous revocation,in which the revocation operations(i.e.,re-signing key generation and resigning process)and the user's revocation are asynchronous.All the revocation operations must be able to be performed without the participation of the revoked user.Even more ambitiously,the revocation process should not rely on any special entity,such as the data owner or a trusted agency.To address this problem,we propose a novel public data integrity verification mechanism in which the data blocks signed by the revoked user will be resigned by another valid user.From the perspectives of security and practicality,the revoked user does not participate in the resigning process and the re-signing key generation.Our scheme allows anyone in the cloud computing system to act as the verifier to publicly and efficiently verify the integrity of the shared data using Homomorphic Verifiable Tags(HVTs).Moreover,the proposed scheme resists the collusion attack between the cloud server and the malicious revoked users.The numerical analysis and experimental results further validate the high efficiency and scalability of the proposed scheme.The experimental results manifest that re-signing 10,000 data blocks only takes 3.815 s and a user can finish the verification in 300 ms with a 99% error detection probability.

Tree-Based Revocation for Certificateless Authentication in Vehicular Ad-Hoc Networks

This work proposes authentication based on identity as a way to increase the efficiency and security of communications in vehicular ad-hoc networks. When using identity-based cryptography to achieve certificateless authentication, membership revocation is not a trivial problem. Thus, in order to improve the performance of revocation in such networks, the use of a dynamic authenticated data structure based on perfect k-ary hash trees combined with a duplex version of the new standard SHA-3 is here presented. Efficient algorithms in the used revocation trees allow reaching a refresh rate of at most simple updates per inserted node. Consequently, the proposal is especially useful for situations with frequent revocations, which are foreseeable when vehicular ad- hoc networks are widely deployed.

Attribute-Based Secure Data Sharing with Efficient Revocation in Fog Computing

Fog computing is a concept that extends the paradigm of cloud computing to the network edge. The goal of fog computing is to situate resources in the vicinity of end users. As with cloud computing, fog computing provides storage services. The data owners can store their confidential data in many fog nodes, which could cause more challenges for data sharing security. In this paper, we present a novel architecture for data sharing in a fog environment. We explore the benefits of fog computing in addressing one-to-many data sharing applications. This architecture sought to outperform the cloud-based architecture and to ensure further enhancements to system performance, especially from the perspective of security. We will address the security challenges of data sharing, such as fine-grained access control, data confidentiality, collusion resistance, scalability, and the issue of user revocation. Keeping these issues in mind, we will secure data sharing in fog computing by combining attributebased encryption and proxy re-encryption techniques. Findings of this study indicate that our system has the response and processing time faster than classical cloud systems. Further, experimental results show that our system has an efficient user revocation mechanism, and that it provides high scalability and sharing of data in real time with low latency.

Research on the Commutation Revocation

In order to resist some prisoner who have received rewards of commutation to implement some illegal or criminal behavior in the course of imprisonment, the system of commutation revocation must be established, which can advantage imprisonment and reduce the costs of imprisonment. The system of commutation revocation can obey to the criminal policy of temper justice with mercy and the principle of ＂collecting mistakes whenever discovered＂ and obtain the penalty goal of special prevention. In order to protect some prisoner＇ s benefit, the prisoner who be revoked the rewards of commutation can take part in the course of juice, the postbox which be opened only by the NPC and committee must be installed in prison. This will be advantage of some prisoner who be revoked the rewards of commutation appealing to the NPC and committee. Because of weakness of necessarily and execution, the system of commutation revocation cannot be established when the prisoner have been released currently.

Attribute-Based Access Control for Multi-Authority Systems with Constant Size Ciphertext in Cloud Computing

In most existing CP-ABE schemes, there is only one authority in the system and all the public keys and private keys are issued by this authority, which incurs ciphertext size and computation costs in the encryption and decryption operations that depend at least linearly on the number of attributes involved in the access policy. We propose an efficient multi-authority CP-ABE scheme in which the authorities need not interact to generate public information during the system initialization phase. Our scheme has constant ciphertext length and a constant number of pairing computations. Our scheme can be proven CPA-secure in random oracle model under the decision q-BDHE assumption. When user's attributes revocation occurs, the scheme transfers most re-encryption work to the cloud service provider, reducing the data owner's computational cost on the premise of security. Finally the analysis and simulation result show that the schemes proposed in this thesis ensure the privacy and secure access of sensitive data stored in the cloud server, and be able to cope with the dynamic changes of users' access privileges in large-scale systems. Besides, the multi-authority ABE eliminates the key escrow problem, achieves the length of ciphertext optimization and enhances the effi ciency of the encryption and decryption operations.

Improving Security and Sharing in Online Social Efficiency for Encrypted Data Networks

Despite that existing data sharing systems in online social networks （OSNs） propose to encrypt data before sharing, the multiparty access control of encrypted data has become a challenging issue. In this paper, we propose a secure data sharing scheme in 0SNs based on ciphertext-policy attribute- based proxy re-encryption and secret sharing. In order to protect users＇ sensitive data, our scheme allows users to customize access policies of their data and then outsource encrypted data to the OSNs service provider. Our scheme presents a multiparty access control model, which enables the disseminator to update the access policy of ciphertext if their attributes satisfy the existing access policy. Further, we present a partial decryption construction in which the computation overhead of user is largely reduced by delegating most of the decryption operations to the OSNs service provider. We also provide checkability on the results returned from the OSNs service provider to guarantee the correctness of partial decrypted ciphertext. Moreover, our scheme presents an efficient attribute revocation method that achieves both forward and backward secrecy. The security and performance analysis results indicate that the proposed scheme is secure and efficient in OSNs.

An Anonymous Authentication Scheme for Plugin Electric Vehicles Joining to Charging/Discharging Station in Vehicle-to-Grid(V2G) Networks

Incorporating electric vehicles into smart grid,vehicle-to-Grid(V2G) makes it feasible to charge for large-scale electric vehicles,and in turn support electric vehicles,as mobile and distributed storage units,to discharge to smart grid.In order to provide reliable and efficient services,the operator of V2 G networks needs to monitor realtime status of every plug-in electric vehicle(PEV) and then evaluate current electricity storage capability.Anonymity,aggregation and dynamic management are three basic but crucial characteristics of which the services of V2 G networks should be.However,few of existing authentication schemes for V2 G networks could satisfy them simultaneously.In this paper,we propose a secure and efficient authentication scheme with privacy-preserving for V2 G networks.The scheme makes the charging/discharging station authenticate PEVs anonymously and manage them dynamically.Moreover,the monitoring data collected by the charging/discharging station could be sent to a local aggregator(LAG)in batch mode.In particular,time overheads during verification stage are independent with the number of involved PEVs,and there is no need to update the membership certificate and key pair before PEV logs out.

Method of secure, scalable, and fine-grained data access control with efficient revocation in untrusted cloud

Cloud computing is a developing computing paradigm in which resources of the computing infrastructure are provided as services over the network. Hopeful as it is, this paradigm also brings new challenges for data security and encryption storage when date owner stores sensitive data for sharing with untrusted cloud servers. When it comes to fine-grained data and scalable access control, a huge computation for key distribution and data management is required. In this article, we achieved this goal by exploiting and uniquely combining techniques of ciphertext-policy attribute-based encryption （CP-ABE）, linear secret sharing schemes （LSSS）, and counter （CTR） mode encryption. The proposed scheme is highly efficient by conducting the revocation on attribute level rather than on user level. The goals of data confidentiality and no collusion attack （even the cloud servers （CS） collude with users）, as well as ones of fine-grainedness and scalability, are also achieved in our access structure.

A Traceable Capability-based Access Control for IoT

Delegation mechanism in Internet of Things(IoT)allows users to share some of their permissions with others.Cloud-based delegation solutions require that only the user who has registered in the cloud can be delegated permissions.It is not convenient when a permission is delegated to a large number of temporarily users.Therefore,some works like CapBAC delegate permissions locally in an offline way.However,this is difficult to revoke and modify the offline delegated permissions.In this work,we propose a traceable capability-based access control approach(TCAC)that can revoke and modify permissions by tracking the trajectories of permissions delegation.We define a time capability tree(TCT)that can automatically extract permissions trajectories,and we also design a new capability token to improve the permission verification,revocation and modification efficiency.The experiment results show that TCAC has less token verification and revocation/modification time than those of CapBAC and xDBAuth.TCAC can discover 73.3%unvisited users in the case of delegating and accessing randomly.This provides more information about the permissions delegation relationships,and opens up new possibilities to guarantee the global security in IoT delegation system.To the best of our knowledge,TCAC is the first work to capture the unvisited permissions.

Active Authentication Protocol for IoV Environment with Distributed Servers

The Internet of Vehicles(IoV)has evolved as an advancement over the conventional Vehicular Ad-hoc Networks(VANETs)in pursuing a more optimal intelligent transportation system that can provide various intelligent solutions and enable a variety of applications for vehicular traffic.Massive volumes of data are produced and communicated wirelessly among the different relayed entities in these vehicular networks,which might entice adversaries and endanger the system with a wide range of security attacks.To ensure the security of such a sensitive network,we proposed a distributed authentication mechanism for IoV based on blockchain technology as a distributed ledger with an ouroboros algorithm.Using timestamp and challenge-responsemechanisms,the proposed authentication model can withstand several security attacks such asMan-in-Middle(MiM)attacks,Distributed Denial of Service(DDoS)attacks,server spoofing attacks and more.The proposed method also provides a solution for single-point failure,forward secrecy,revocability,etc.We exhibit the security of our proposed model by using formal(mathematical)analysis and informal analysis.We used Random Oracle Model to perform themathematical analysis.In addition,we compared the communication cost,computation cost,and security of the proposed model with the related existing studies.We have verified the security of the model by using AVISPA tool simulation.The security analysis and computation analysis show that the proposed protocol is viable.

Novel dynamic anti-collusion ciphertext policy attribute-based encryption scheme in 5G D2D environment

To share data securely with secure attribute revocation,anti-collusion,and dynamic user management in the 5G device-to-device(D2D)environment,a novel dynamic anti-collusion ciphertext policy attribute-based encryption(NDA-CP-ABE)scheme in the 5G D2D environment is proposed.On the basis of the ciphertext policy attribute-based encryption algorithm,fine-grained access control and secure attribute revocation are realized,and the confidentiality of data is guaranteed.A polynomial function is adopted in the ciphertext generation phase to realize dynamic user management.A random number is used to prevent a collusion attack among the legitimate user equipment(UE),revoked UE,and external network attackers.Finally,on the basis of the Diffie-Hellman problem,the NDA-CP-ABE scheme is formally proved,and the simulation performances are compared with those of similar schemes.The results show that data can be securely shared through a D2D channel with secure attribute revocation,anti-collusion,and dynamic user management.Moreover,compared with similar schemes,the NDA-CP-ABE scheme has higher efficiency in encryption,decryption,and storage.