New method for file deduplication in cloud storage

Deduplication is widely used in cloud storage service to save bandwidth and storage resources,however,the security of client deduplication still flaws in an external attack to access a user’s private data.Xu-CDE,a deduplication solution of encrypting data for multi-client was first proposed,which could protect the privacy of data from the external attackers and honest but curious server,with favorable theoretical meaning and representativeness.However,in Xu-CDE,the user ownership authentication credentials were lack of instantaneity protection,which could not resist replay attack.As an improvement to the flaw,the protocol MRN-CDE (MLE based and random number modified client-side deduplication of encrypted data in cloud storage) was proposed,adding random number in order to ensure the instantaneity of the authentication credentials,and using the algorithm of MLE-K_Pto extract key from original file to replace the file itself as an encryption key.As a consequence,the new protocol improved security while significantly reduced the amount of computation.After the safety analysis and the actual tests,results show that based on Xu-CDE,the proposed protocol MRN-CDE has stronger security of ownership,and improves time efficiency.Specially,the new protocol works better on large files in cloud with a certain value.     

Threshold re-encryption based secure deduplication method for cloud data with resistance against side channel attack

For security and efficiency problems in threshold based deduplication for cloud data,a novel method based on threshold re-encryption was proposed to deal with side channel attacks.A lightweight threshold re-encryption mechanism was presented to transfer the secondary encryption to the cloud for execution and allow clients to generate ciphertext based on key segmentation instead of ciphertext segmentation,both of which largely reduce computational overhead of clients.Also,the proposed mechanism enables clients to decrypt from both one-time encrypted and re-encrypted ciphertext,thus avoiding the overhead of redundant encryption of the same file.Mutual integrity verification between cloud service provider and clients was also supported by the proposed method,which directly ensured the correctness of the correspondence between ciphertext and plaintext on client side.Experiments show that the proposed method not only largely reduces the computational overhead on client side,but also achieves superior storage performance on cloud side simultaneously.     

基于DDCT表的多副本完整性审计方案

在云存储环境下,云数据采用多副本存储已经成为一种流行的应用.针对恶意云服务提供商威胁云副本数据安全问题,提出一种基于DDCT（Dynamic Divide and Conquer Table）表的多副本完整性审计方案.首先引入DDCT表来解决数据动态操作问题,同时表中存储副本数据的块号、版本号和时间戳等信息;接下来为抵制恶意云服务商攻击,设计一种基于时间戳的副本数据签名认证算法;其次提出了包括区块头和区块体的副本区块概念,区块头存储副本数据基于时间戳识别认证的签名信息,区块体存放加密的副本数据;最后委托第三方审计机构采用基于副本时间戳的签名认证算法来审计云端多副本数据的完整性.通过安全性分析和实验对比,本方案不仅有效的防范恶意存储节点之间的攻击,而且还能防止多副本数据泄露给第三方审计机构.     

云存储中密文数据的客户端安全去重方案

云存储环境下,客户端数据去重能在本地进行文件重复性检测,有效地节约存储空间和网络带宽.然而,客户端去重仍面临着很多安全挑战.首先,由于将文件哈希值作为重复性检测的证据,攻击者很可能通过一个文件的哈希值获得整个文件;其次,为了保护数据隐私,收敛加密被广泛运用于数据去重方案,但是由于数据本身是可预测的,所以收敛加密仍不可避免地遭受暴力字典攻击.为了解决上述问题,本文首次利用盲签名构造了一个安全的密钥生成协议,通过引入一个密钥服务器,实现了对收敛密钥的二次加密,有效地预防了暴力字典攻击;并进一步提出了一个基于块密钥签名的拥有权证明方法,能够有效预防攻击者通过单一的哈希值来获取文件,并能同时实现对密文文件的文件级和块级去重.同时,安全分析表明本文方案在随机预言模型下是可证明安全的,并能够满足收敛密钥安全、标签一致性和抗暴力字典攻击等更多安全属性.此外,与现有方案相比,实验结果表明本文方案在文件上传和文件去重方面的计算开销相对较小.     

Cloud data secure deduplication scheme via role-based symmetric encryption

The rapid development of cloud computing and big data technology brings prople to enter the era of big data,more and more enterprises and individuals outsource their data to the cloud service providers.The explosive growth of data and data replicas as well as the increasing management overhead bring a big challenge to the cloud storage space.Meanwhile,some serious issues such as the privacy disclosure,authorized access,secure deduplication,rekeying and permission revocation should also be taken into account.In order to address these problems,a role-based symmetric encryption algorithm was proposed,which established a mapping relation between roles and role keys.Moreover,a secure deduplication scheme was proposed via role-based symmetric encryption to achieve both the privacy protection and the authorized deduplication under the hierarchical architecture in the cloud computing environment.Furthermore,in the proposed scheme,the group key agreement protocol was utilized to achieve rekeying and permission revocation.Finally,the security analysis shows that the proposed role-based symmetric encryption algorithm is provably secure under the standard model,and the deduplication scheme can meet the security requirements.The performance analysis and experimental results indicate that the proposed scheme is effective and efficient.     

Authentication scheme for multi-cloud environment based on smart card

To solve the problem of the access keys stored in a smart card increasing linearly with the number of registered clouds without third party participated in authentication,an authentication scheme was proposed for multi-cloud environment based on smart card.In the proposed scheme,the authentication was realized between user and multiple clouds without third party participation when the smart card only stored two access key.Thus the storage cost of smart card was reduced effectively.Because there was no public key cryptography,the authentication messages was generated by using XOR homomorphic function and Hash function,thus the computational cost of the smart card and the cloud servers was reduced effectively.Moreover,the proposed scheme also didn’t need to store any user’s information on the cloud servers,thereby reducing the storage and management costs of the cloud servers.The security analysis and the performance analysis show that the proposed scheme is able to resist multiple attacks,which is secure and efficient.     

基于云平台的安全审计系统设计与实现

针对云平台日志信息的安全审计及安全存储的需求,提出一种云平台的支持审计信息安全存储的审计系统实现方案.提出的安全审计系统由审计信息记录、审计信息签名、审计信息管理3个功能模块组成,采用Web Services、数字签名等关键技术,实现了对用户信息的获取、分析与数据库存储等功能.另外,系统在实现了网络安全审计的功能基础上,通过对数据库表项信息进行元组签名与分片签名结合的方式,保证了数据的安全与可信.与现有的云平台的安全审计系统实现方案相比,该方案安全性和实用性很高,并具有较好的可移植性.     

Privacy-Preserving Public Auditing for Non-manager Group Shared Data

By the widespread use of cloud storage service, users get a lot of conveniences such as low-price file remote storage and flexible file sharing. The research points in cloud computing include the verification of data integrity, the protection of data privacy and flexible data access. The integrity of data is ensured by a challenge-and-response protocol based on the signatures generated by group users. Many existing schemes use group signatures to make sure that the data stored in cloud is intact for the purpose of privacy and anonymity. However, group signatures do not consider user equality and the problem of frameability caused by group managers. Therefore, we propose a data sharing scheme PSFS to support user equality and traceability meanwhile based on our previous work HA-DGSP. PSFS has some secure properties such as correctness, traceability, homomorphic authentication and practical data sharing. The practical data sharing ensures that the data owner won’t loss the control of the file data during the sharing and the data owner will get effective incentive of data sharing. The effective incentive is realized by the technology of blockchain. The experimental results show that the communication overhead and computational overhead of PSFS is acceptable.     

Research progress on secure data deduplication in cloud

In order to improve the efficiency of cloud storage and save the communication bandwidth, a deduplication mechanism for multi-duplicate of the same data in cloud environment was needed. However, the implement of the secure data deduplication was seriously hindered by the ciphertext in cloud. This issue has quickly aroused wide attention of academia and industry, and became a research hotspot. From a security standpoint, firstly the primary cause and the main challenges of secure data deduplication in cloud environment was analyzed, and then the deduplication system model as well as its security model was described. Furthermore, focusing on the realization mechanism of secure data deduplica-tion, the thorough analyses were carried on and reviews for the related research works in recent years from content-based encryption, proof of ownership and privacy protection for secure deduplication, then the advantages and common prob-lems of various key technologies and methods were summed up. Finally, the future research directions and development trends on secure data deduplication in cloud was given.     

Key-exposure resilient integrity auditing scheme with encrypted data deduplication

For the problems of key-exposure,encrypted data duplication and integrity auditing in cloud data storage,a public auditing scheme was proposed to support key update and encrypted data deduplication.Utilizing Bloom filters,the proposed scheme could achieve client-side deduplication,and guaranteed that the key exposure in one time period didn’t effect the users’ private key in other time periods.The proposed scheme could solve the conflict between key-exposure resilient and encrypted data deduplication in public auditing scheme for the first time.Security analysis indicates that the proposed scheme is strong key-exposure resilient,confidentiality,detectability,and unforgeability of authentication tags and tokens under the computation Diffie-Hellman hardness assumption in the random oracle model.     

Data access control policy of encrypted deduplication system

To solve the problem that convergent encryption was commonly used in existing encrypted deduplication systems in cloud storage and data owner couldn’t effectively enforce access control on their outsourced data,an encrypted deduplication system was proposed to support access control functions such as identity authentication,authorization deduplication and the update of access control policy.The outsourced data was only deduplicated with the authorized users,and the unauthorized users couldn’t obtain any data information.CP-ABE and the partition of the ElGamal private key were used to update the access control policy of data.Self-control objects was used to encapsulate user’s data and its access policy,providing authentication for data visitors and ensuring the access control policies enforced effectively.Security analysis and simulation results demonstrate that the proposed system enables data access control and executes efficiently.     

卫士通安全桌面云助力企业云落地

介绍了卫士通安全桌面云系统的架构及组成、系统功能及特色,及系统的典型部署设计。卫士通安全桌面云系统综合运用了桌面云、商用密码、安全存储和虚拟化安全等技术,在确保企业数据大集中的前提下,实现了用户统一身份认证、安全访问控制、资源及行为监控审计、数据集中安全存储、操作系统安全加固等一系列安全功能,既可以应用到普通的办公网环境中,也可以应用到有大量硬件开发的科研院所的研发环境中。     

Request Merging Based Cross-User Deduplication for Cloud Storage with Resistance Against App ending Chunks Attack

Cross-user deduplication is an emerging technique to eliminate redundant uploading in cloud storage. Its deterministic response indicating the existence of data creates a side channel to attackers, which makes the privacy in the cloud at risk. Such kind of attack as well as further appending chunks attack, still cannot be well resisted in current solutions, thus is becoming a big obstacle in using this technique. We propose a secure cross-user deduplication, called Request merging based deduplication scheme (RMDS), which takes the lead to consider resistance against appending chunks attack in a lightweight way, let alone side channel attack. We utilize the proposed XOR based chunk-level server-side storage structure together with a request merging strategy to obfuscate attackers in minimized communication overhead. The experiment results show that, with security guaranteed, the proposed scheme is more efficient comparing with the state of the art.     

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。     

Provable data possession scheme based on public verification and private verification

More and more users choose to transfer their applications and data into the cloud.Data security is a key issue for cloud storage systems.To ensure the integrity and validity of the data stored in the cloud,provable data possession (PDP) scheme is particularly important.In order to verify whether the cloud storage service provider had stored the data of the user completely,a scheme on the basis of NRPDP (non-repudiable PDP) was improved and extended,and a data retention scheme based on public authentication and private authentication was proposed.The scheme can verify the trustworthiness of the service provider and the user in the cloud storage at the same time,which satisfies the non-repudiation of the verification.The theory proves the non-repudiation of the proposed scheme.The experiment proves that the efficiency of each stage is better than that of the existing single public verification method or private authentication method.     

Slight Homomorphic Signature for Access Controlling in Cloud Computing

With the popularity of cloud computing, how to securely authenticate a user while not releasing user’s sensitive information becomes a challenge. In this paper, we introduce a slight homomorphic signature, which is suitable to implement an access controlling service in cloud computing. In slight homomorphic signature, each user in cloud computing who have a set of identity attributes, firstly computes a full signature on all his identity attributes, and sends it to a semi-trusted access controlling server. The access controlling server verifies the full signature for all identity attributes. After then, if the user wants to require a cloud service, which may have a special requirement on one of the identity attributes, the user only needs to securely send the cloud service’s name to the access controlling server. The access controlling server which does not know the secret key can compute a partial signature on this special identity attribute, and then sends it to the cloud server for authentication. In the paper, we give a formal secure definition of this slight homomorphic signature, and construct a scheme from Boneh–Boyen signature. We prove that our scheme is secure under q-SDH problem with a weak adversary.     

Secure‐aware and privacy‐preserving electronic health record searching in cloud environment

Cloud storage has become a trend of storage in modern age. The cloud‐based electronic health record (EHR) system has brought great convenience for health care. When a user visits a doctor for a treatment, the doctor may be necessary to access the history health records generated at other medical institutions. Thus, we present a secure EHR searching scheme based on conjunctive keyword search with proxy re‐encryption to realize data sharing between different medical institutions. Firstly, we propose a framework for health data sharing among multiple medical institutions based on cloud storage. We explore the public key encryption with conjunctive keyword search to encrypt the original data and store it in the cloud. It ensures data security with searchability. Furthermore, we adopt the identity‐based access control mechanism and proxy re‐encryption scheme to guarantee the legitimacy of access and the privacy of the original data. Generally speaking, our work can achieve authentication, keyword privacy, and privacy preservation. Moreover, the performance evaluation shows that the scheme can achieve high computational efficiency.     

Anonymity handover authentication protocol based on group signature for wireless Mesh network

In order to ensure that the Mesh network mobile client video,voice and other real-time strong applications without interruption,a secure and efficient handover authentication was very important.To protect the privacy of mobile nodes,an anonymity handover authentication protocol was proposed based on group signature for wireless mesh network.Compared with other handover authentication protocols based on group signature,the proposed scheme did not involve the group signature correlation operation,and the group signature algorithm was only carried out on the router.The pro-posed protocol not only enhances the security but also performs well in authentication efficiency and privacy-preserving.     

基于属性加密的高效密文去重和审计方案

针对当前支持去重的属性加密方案既不支持云存储数据审计,又不支持过期用户撤销,且去重搜索和用户解密效率较低的问题,该文提出一种支持高效去重和审计的属性加密方案。该方案引入了第3方审计者对云存储数据的完整性进行检验,利用代理辅助用户撤销机制对过期用户进行撤销,又提出高效去重搜索树技术来提高去重搜索效率,并通过代理解密机制辅助用户解密。安全性分析表明该方案通过采用混合云架构,在公有云达到IND-CPA安全性,在私有云达到PRV-CDA安全性。性能分析表明该方案的去重搜索效率更高,用户的解密计算量较小。     

A novel RSA algorithm for secured key transmission in a centralized cloud environment

Cloud computing has been gaining widespread significance in recent times, especially with the advent of state‐of‐the‐art communication technologies and data‐handling systems. Large volumes of data are being handled in real time and their availability is made feasible to consumers in an efficient manner through cloud computing networks. However, security of such data being transferred through clouds characterized in a centralized configuration is of prime concern, which has been investigated in this research paper. Secured transmission of data through a secured key transmission using appropriate authentication mechanism has been the driving force behind the research carried out in this paper. In order to resolve the existing issues in clouds in terms of computational as well as storage complexities, a secure key transmission Rivest‐Shamir‐Adleman (SKT‐RSA) protocol is proposed based on the secure key transmission. Key distribution between the certified authority and the end user is proposed. The proposed protocol is a tree‐based cluster key distribution scheme.