支持策略隐藏且密文长度恒定的可搜索加密方案

属性加密体制是实现云存储中数据灵活访问控制的关键技术之一,但已有的属性加密方案存在密文存储开销过大和用户隐私泄露等问题,并且不能同时支持云端数据的公开审计。为了解决这些问题,该文提出一个新的可搜索属性加密方案,其安全性可归约到q-BDHE问题和CDH问题的困难性。该方案在支持关键词搜索的基础上,实现了密文长度恒定;引入策略隐藏思想,防止攻击者获取敏感信息,确保了用户的隐私性;通过数据公开审计机制,实现了云存储中数据的完整性验证。与已有的同类方案相比较,该方案有效地降低了数据的加密开销、关键词的搜索开销、密文的存储成本与解密开销,在云存储环境中具有较好的应用前景。     

Secure personal data sharing in cloud computing using attribute-based broadcast encryption

The ciphertext-policy (CP) attribute-based encryption (ABE) (CP-ABE) emergings as a promising technology for allowing users to conveniently access data in cloud computing. Unfortunately, it suffers from several drawbacks such as decryption overhead, user revocation and privacy preserving. The authors proposed a new efficient and privacy-preserving attribute-based broadcast encryption (BE) (ABBE) named EP-ABBE, that can reduce the decryption computation overhead by partial decryption, and protect user privacy by obfuscating access policy of ciphertext and user's attributes. Based on EP-ABBE, a secure and flexible personal data sharing scheme in cloud computing was presented, in which the data owner can enjoy the flexibly of encrypting personal data using a specified access policy together with an implicit user index set. With the proposed scheme, efficient user revocation is achieved by dropping revoked user's index from the user index set, which is with very low computation cost. Moreover, the privacy of user can well be protected in the scheme. The security and performance analysis show that the scheme is secure, efficient and privacy-preserving.     

Multiuser access control searchable privacy‐preserving scheme in cloud storage

Searchable encryption scheme‐based ciphertext‐policy attribute‐based encryption (CP‐ABE) is a effective scheme for providing multiuser to search over the encrypted data on cloud storage environment. However, most of the existing search schemes lack the privacy protection of the data owner and have higher computation time cost. In this paper, we propose a multiuser access control searchable privacy‐preserving scheme in cloud storage. First, the data owner only encrypts the data file and sets the access control list of multiuser and multiattribute for search data file. And the computing operation, which generates the attribute keys of the users' access control and the keyword index, is given trusted third party to perform for reducing the computation time of the data owner. Second, using CP‐ABE scheme, trusted third party embeds the users' access control attributes into their attribute keys. Only when those embedded attributes satisfy the access control list, the ciphertext can be decrypted accordingly. Finally, when the user searches data file, the keyword trap door is no longer generated by the user, and it is handed to the proxy server to finish. Also, the ciphertext is predecrypted by the proxy sever before the user performs decryption. In this way, the flaw of the client's limited computation resource can be solved. Security analysis results show that this scheme has the data privacy, the privacy of the search process, and the collusion‐resistance attack, and experimental results demonstrate that the proposed scheme can effectively reduce the computation time of the data owner and the users.     

QMLFD Based RSA Cryptosystem for Enhancing Data Security in Public Cloud Storage System

Nowadays sharing secure data turns out to be a challenging task for the data owner due to its privacy and confidentiality. Several IT companies stores their important information in the cloud since computing has developed immense power in sharing the data. On the other hand, privacy is considered a serious issue in cloud computing as there are numerous privacy concerns namely integrity, authentication as well as confidentiality. Among all those concerns, this paper focuses on enhancing the data integrity in the public cloud environment using Qusai modified levy flight distribution for the RSA cryptosystem (QMLFD-RSA). An effective approach named QMLFD for the RSA cryptosystem is proposed for resolving the problem based on data integrity in public cloud environment. A secured key generation and data encryption are done by employing the RSA cryptosystem thus the data is secured from unauthorized users. The key selection is done by using quasi based modified Levy flight distribution algorithm. Thus the proposed approach provides an effective model to enhance the integrity of data in cloud computing thus checking the data integrity uploaded in the public cloud storage system. In addition to this, ten optimization benchmark functions are calculated to determine the performances and the functioning of the newly developed QMLFD algorithm. The simulation results and comparative performances are carried out and the analysis reveals that the proposed QMLFD for the RSA cryptosystem provides better results when compared with other approaches.

     

Analysis and improvement on identity-based cloud data integrity verification scheme

Many individuals or businesses outsource their data to remote cloud.Cloud storage provides users the advantages of economic convenience,but data owners no longer physically control over the stored data,which introduces new security challenges,such as no security guarantees of integrity and privacy.The security of two identity-based cloud data integrity verification schemes by Zhang et al and Xu et al respectively are analysed.It shows that Zhang et al.’s scheme is subjected to secret key recovery attack for the cloud servers can recover user’s private key only utilizing stored data.And Xu et al.’s scheme cannot satisfy security requirements of soundness.Based on Xu et al.'s scheme,a modified identity-based cloud data integrity verification scheme is proposed.A comprehensive analysis shows the new scheme can provide the security requirements of soundness and privacy,and has the same communication overhead and computational cost as Xu et al.’s scheme.     

Secure Data Access and Sharing Scheme for Cloud Storage

Cloud storage is a new storage mode emerged along with the development of cloud computing paradigm. By migrating the data to cloud storage, the consumers can be liberated from building and maintaining the private storage infrastructure, and they can enjoy the data storage service at anywhere and anytime with high reliability and a relatively low cost. However, the security and privacy risks, especially the confidentiality and integrity of data seem to be the biggest hurdle to the adoption of the cloud storage applications. In this paper, we consider the secure data access and sharing issues for cloud storage services. Based on the intractability of the discrete logarithm problem, we design a secure data access and data sharing scheme for cloud storage, where we utilize the user authentication scheme to deal with the data access problem. According to our analysis, through our scheme, only valid user with the correct password and biometric can access to the cloud storage provider. Besides, the authorized users can access the rightful resources and verify the validity of the shared data, but cannot transfer the permission to any other party. At the same time, the confidentiality and integrity of data can be guaranteed.

     

Secure and privacy‐preserving keyword search retrieval over hashed encrypted cloud data

Cloud computing (CC) is the universal area in which the data owners will contract out their pertinent data to the untrusted public cloud that permits the data users to retrieve the data with complete integrity. To give data privacy along with integrity, majority of the research works were concentrated on single data owner for secure searching of encrypted data via the cloud. Also, searchable encryption supports data user to retrieve the particular encrypted document from encrypted cloud data via keyword search (KS). However, these researches are not efficient for keyword search retrieval. To trounce such drawbacks, this paper proposes efficient secure and privacy‐preserving keyword search retrieval (SPKSR) system, in which the user retrieves the hashed encrypted documents over hashed encrypted cloud data. The proposed system includes three entities explicitly, (a) data owner (DO), (b) cloud server (CS), and (c) data users (DU). The owner outsources hashed encrypted documents set, along with generated searchable index tree to the CS. The CS hoards the hashed encrypted document collection and index tree structure. DU performs the “search” over the hashed encrypted data. Experimental results of the proposed system are analyzed and contrasted with the other existent system to show the dominance of the proposed system.     

ACDAS: Authenticated controlled data access and sharing scheme for cloud storage

Cloud storage services require cost‐effective, scalable, and self‐managed secure data management functionality. Public cloud storage always enforces users to adopt the restricted generic security consideration provided by the cloud service provider. On the contrary, private cloud storage gives users the opportunity to configure a self‐managed and controlled authenticated data security model to control the accessing and sharing of data in a private cloud. However, this introduces several new challenges to data security. One critical issue is how to enable a secure, authenticated data storage model for data access with controlled data accessibility. In this paper, we propose an authenticated controlled data access and sharing scheme called ACDAS to address this issue. In our proposed scheme, we employ a biometric‐based authentication model for secure access to data storage and sharing. To provide flexible data sharing under the control of a data owner, we propose a variant of a proxy reencryption scheme where the cloud server uses a proxy reencryption key and the data owner generates a credential token during decryption to control the accessibility of the users. The security analysis shows that our proposed scheme is resistant to various attacks, including a stolen verifier attack, a replay attack, a password guessing attack, and a stolen mobile device attack. Further, our proposed scheme satisfies the considered security requirements of a data storage and sharing system. The experimental results demonstrate that ACDAS can achieve the security goals together with the practical efficiency of storage, computation, and communication compared with other related schemes.     

Secure deduplication and integrity audit system based on convergent encryption for cloud storage

Cloud storage applications quickly become the best choice of the personal user and enterprise storage with its convenience,scalability and other advantages,secure deduplication and integrity auditing are key issues for cloud storage.At first,convergent key encapsulation/decoupling algorithm based on blind signature was set up,which could securely store key and enable it to deduplicate.Besides,a BLS signature algorithm based on convergence key was provided and use TTP to store public key and proxy audit which enables signature and pubic key deduplication and reduces client storage and computing overhead.Finally,cloud-based secure deduplicaion and integrity audit system was designed and implemented.It offered user with data privacy protection,deduplication authentication,audit authentication services and lowered client and cloud computation overhead.     

基于云存储的文件共享策略研究

云存储具有高可扩展性、低成本等特点,为用户文件共享提供了经济高效的服务,同时也带来了新的安全问题:在不可信的云存储中,如何在保证文件的安全和隐私的前提下,为特定用户共享。该方案提出了基于身份的公钥密码体制基础上,运用高效安全的代理环签名、动态广播加密和双线性对技术,通过授权用户列表,能动态加入和撤销共享用户,不需要更改老用户相关密钥。该方案简单可行,具有可追溯性、匿名性、不可伪造性等特点。     

Design of a Guitar Shaped UWB Antenna with Wide Band Notched Characteristics for Wireless Applications

Cloud storage is a cloud based service which delivers scalable on demand on line storage of data and eliminates the need of maintaining local data centre. Storage of data in cloud brings many advantages such as lower-cost, metered service, scalable and ubiquitous access. However, it also raises concerns to its integrity; to save the storage space cloud service provider may delete some rarely access data. Data privacy is another issue which must be addressed to increase data owner’s trust. To address above issues, many researchers have proposed public auditing schemes to validate the integrity of data using third party auditor. These schemes generate metadata using data files on the owner side and store these metadata on the cloud storage along with the file data, which helps in auditing. These schemes address many concerns which arise due to remote data storage. However, computation cost involved for metadata generation at the data owner side is not properly addressed; another issue which is not properly addressed is an iniquitous third party auditor may be the source of denial of service attack by issuing constantly large number of audit request. Our scheme solves these issues by lowering the computation cost at data owner side and controlling the number of times a third party auditor can issue an audit request to the cloud storage. Our Scheme also supports secure access of data using conditional proxy re-encryption scheme and delegation of auditing task by the authorized third party auditor to another auditor for the specified period of times in the case of unavailability of authorized third party auditor.

     

一种基于ORAM的数据可恢复性证明与访问模式的隐藏

随着云计算的发展与应用,越来越多的客户选择云存储作为存储媒质,因此,数据的完整性和私密性成为客户关心的主要问题。基于无关RAM模型机提出一种新的结构,将客户文件分割成大小相等的数据块,每个数据块在云存储中有两个备份,且随机地存储在不同的文件中,以保证数据的完整性。利用同态散列算法验证数据的可持有性,通过无关RAM隐藏客户对服务器的访问模式,敌手无法从客户的数据访问模式中获取有用的信息,从而实现了数据的私密性。     

基于区块链的细粒度云数据安全存储与删除方案

在基于云计算的存储与删除服务中,由于外包数据所有权和管理分离,现有的逻辑删除机制使云上的数据很容易暴露给未经授权的用户,甚至云服务器可能未遵循用户要求删除相应数据。为此,该文提出一种细粒度的安全云端数据存储与删除方案。基于椭圆曲线构造了基于密文策略的属性基加密以实现外包数据细粒度访问控制,应用区块链实现可公开验证的安全数据删除。该文方案具有责任可追踪性以及两方删除与可验证性等特性。理论分析与实验结果表明该文方案具有较好的安全性和较高的性能,能够满足云数据共享与安全删除的需求。     

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.     

基于身份的具有否认认证的关键字可搜索加密方案

云存储技术的发展实现了资源共享,为用户节省了数据管理开销.可搜索加密技术,既保护用户隐私又支持密文检索,方便了用户查找云端密文数据.现有的公钥关键字可搜索加密方案虽然支持身份认证,但未实现否认的属性.为了更好地保护发送者的身份隐私,该文将否认认证与公钥关键字可搜索加密技术相结合,提出一种基于身份的具有否认认证的关键字可...     

Privacy-preserving and efficient user matching based on attribute encryption in mobile social networks

With the rapid popularity of social networking platforms, users can be matched when sharing their profiles. However, there is a risk of leakage of sensitive user information during the user matching process, which leads to the lack of user privacy protection. In this paper, we propose a privacy protection scheme based on the encryption of hidden attributes during user matching in mobile social networks, which uses linear secret sharing scheme (LSSS) as the access structure based on ciphertext policy attribute-based encryption (CP-ABE), and the match server can perform friend recommendation by completing bi-directional attribute matching determination without disclosing user attribute information. In addition, the use of selective keywords protects the privacy of requesters and publishers in selecting keywords and selecting plaintext attacks. The scheme reduces the encryption and decryption overhead for users by dividing encryption into a preparation phase and an online phase and shifting most of the decryption overhead from the requester to the match server. The experimental results show that the scheme ensures user privacy while effectively reducing communication overhead.     

A management architecture for client‐defined cloud storage services

Cloud service providers offer virtual resources to users, who then pay for as much as they use. High‐speed networks help to overcome the limitation of geographical distances between clients and cloud servers, which encourage users to adopt cloud storage services for data backup and sharing. However, users use only a few cloud storage services because of the complexity of managing multiple accounts and distributing data to store. In this paper, we propose the client‐defined management architecture (CLIMA) that redefines a storage service by coordinating multiple cloud storage services from clients. We address practical issues of coordinating multiple cloud service providers using a client‐based approach. We implement a prototype as a realization of CLIMA, which achieves both reliability and privacy protection using erasure code and higher performance by optimally scheduling data transmission. We use our prototype to evaluate the benefits of CLIMA on commercial cloud storage service providers. Finally, CLIMA empowers clients to increase the manageability and flexibility of cloud storage services. Copyright © 2015 John Wiley & Sons, Ltd.     

Method of privacy protection based on multiple edge servers in personalized search

In the plaintext environment,users' personalized search results can be obtained through users' interest model and query keywords.However,it may possibly result in the disclosure of sensitive data and privacy,which prevents using sensitive data in cloud search.Therefore,data is generally stored in the form of ciphertext in the cloud server.In the process of cloud search service,users intend to quickly obtain the desired search results from the vast amount of ciphertext.In order to solve the problem,it was proposed that a method of privacy protection based on multiple edge servers in personalized search shall be used.By introducing multiple edge servers and cutting the index as well as the query matrix,the computing relevance scores of partial query and partial file index are achieved on the edge server.The cloud server only needs to get the relevance score on the edge server and make a simple processing that can return to the most relevant Top K files by user query,so as to make it particularly suitable for a large number of users in the massive personalized ciphertext search.Security analysis and experimental results show that this method can effectively protect users’ privacy and data confidentiality.In addition,it can guarantee high efficiency in search to provide better personalized search experience.     

Lightweight integrity verification scheme for cloud based group data

In order to protect the security of the data stored in the cloud by group users,a data integrity verification scheme was designed which can protect the privacy of the group users.The scheme can efficiently detect the shared data in the cloud and support the dynamic updating of the data,and use the characteristic of the ring signature to hide the iden-tity of the signer corresponding to the data block.That is,the third-party verifier can not spy on the users identity and other private information when validating.The aggregated approach is used to generate data labels,which reduces the storage cost of labels and supports the dynamic operation of group data,so that the users in the group can easily modify the cloud group data.     

Data Protection and Data Sharing in Telematics

Automotive telematics may be defined as the information-intensive applications enabled for vehicles by a combination of telecommunications and computing technology. Telematics by its nature requires the capture, storage, and exchange of sensor data to obtain remote services. Such data likely include personal, sensitive information, which require proper handling to protect the driver's privacy. Some existing approaches focus on protecting privacy through anonymous interactions or by stopping information flow altogether. We complement these by concentrating instead on giving different stakeholders control over data sharing and use. In this paper, we identify several data protection challenges specifically related to the automotive telematics domain, and propose a general data protection framework to address some of those challenges. The framework enables data aggregation before data is released to service providers, which minimizes the disclosure of privacy sensitive information. We have implemented the core component, the privacy engine, to help users manage their privacy policies and to authorize data requests based on policy matching. The policy manager provides a flexible privacy policy model that allows data subjects to express rich constraint-based policies, including event-based, and spatio-temporal constraints. Thus, the policy engine can decide on a large number of requests without user assistance and causes no interruptions while driving. A performance study indicates that the overhead is stable with an increasing number of data subjects.