基于属性加密的雾协同云数据共享方案

为解决现有的属性加密数据共享方案粗粒度和开销大等问题,提出一种能保证数据隐私且访问控制灵活的雾协同云数据共享方案(FAC-ABE)。设计属性加密机制,将数据的访问控制策略分为个性化和专业化两种。通过个性化的访问策略,根据用户的经验和偏好,将数据共享给相应的云端。利用雾节点对数据分类,将共享的数据分流,保障数据共享给专业的云服务器。安全分析结果表明,该方案能保障数据机密性,实现更细粒度的访问控制。实验结果表明,用户能将加密开销转移到雾节点上,降低了云端用户开销。     

Hierarchical attribute-based encryption and scalable user revocation for sharing data in cloud servers

With rapid development of cloud computing, more and more enterprises will outsource their sensitive data for sharing in a cloud. To keep the shared data confidential against untrusted cloud service providers (CSPs), a natural way is to store only the encrypted data in a cloud. The key problems of this approach include establishing access control for the encrypted data, and revoking the access rights from users when they are no longer authorized to access the encrypted data. This paper aims to solve both problems. First, we propose a hierarchical attribute-based encryption scheme (HABE) by combining a hierarchical identity-based encryption (HIBE) system and a ciphertext-policy attribute-based encryption (CP-ABE) system, so as to provide not only fine-grained access control, but also full delegation and high performance. Then, we propose a scalable revocation scheme by applying proxy re-encryption (PRE) and lazy re-encryption (LRE) to the HABE scheme, so as to efficiently revoke access rights from users.     

基于属性加密的云存储隐私保护机制研究

以典型的云存储体系结构为研究对象,从数据拥有者、云服务器、授权机构、用户以及用户撤销机制5个方面对云存储系统的隐私保护机制进行了研究,通过分析比较发现,云存储系统中的隐私保护问题主要可以分为系统参与者的身份隐私问题、敏感属性信息泄露问题、云存储系统敏感内容信息泄露问题。针对上述问题,研究了当前基于属性加密的云存储系统隐私保护机制,并讨论了其中存在的不足、可能的解决方案以及未来可能的研究方向。     

A hybrid solution for privacy preserving medical data sharing in the cloud environment

Storing and sharing of medical data in the cloud environment, where computing resources including storage is provided by a third party service provider, raise serious concern of individual privacy for the adoption of cloud computing technologies. Existing privacy protection researches can be classified into three categories, i.e., privacy by policy, privacy by statistics, and privacy by cryptography. However, the privacy concerns and data utilization requirements on different parts of the medical data may be quite different. The solution for medical dataset sharing in the cloud should support multiple data accessing paradigms with different privacy strengths. The statistics or cryptography technology alone cannot enforce the multiple privacy demands, which blocks their application in the real-world cloud. This paper proposes a practical solution for privacy preserving medical record sharing for cloud computing. Based on the classification of the attributes of medical records, we use vertical partition of medical dataset to achieve the consideration of different parts of medical data with different privacy concerns. It mainly includes four components, i.e., (1) vertical data partition for medical data publishing, (2) data merging for medical dataset accessing, (3) integrity checking, and (4) hybrid search across plaintext and ciphertext, where the statistical analysis and cryptography are innovatively combined together to provide multiple paradigms of balance between medical data utilization and privacy protection. A prototype system for the large scale medical data access and sharing is implemented. Extensive experiments show the effectiveness of our proposed solution.     

Secure cloud file sharing scheme using blockchain and attribute-based encryption

This paper presents a novel collaboration scheme for secure cloud file sharing using blockchain and attribute-based encryption(ABE). Blockchain enables us to implement access control as a smart contract between data owner and users. Each data owner creates its own smart contract where in a data user can request to access a specific file by registering a transaction. In response transaction, the data owner sends the required credential to the user thereby enabling her/him to decrypt the intended file on the cloud storage. This scheme is decentralized, fault tolerant and secured against DoS attacks. The cipher-key, which is used for file encryption, is embedded into a set of coefficients of a polynomial so-called access polynomial. It is attached to the encrypted file on the cloud storage as a metadata. The data user can restore the cipher-key by means of the credential receiving in response transaction and access polynomial. The data owner uses ABE scheme in response transaction to impose her/him access policy to the file as well as preserving user anonymity. This scheme supports fast revocation of the user access by means of updating the access polynomial coefficients and without any communication overhead to non-revoked users. Through formal verification, we show that the scheme is secure in terms of secrecy of credential information and authentication of participants. Finally, the evaluation results show that our scheme is scalable with acceptable performance up to 20,000 users.     

Access control based privacy preserving secure data sharing with hidden access policies in cloud

Attribute-based encryption is a promising solution to the access control based data sharing in the cloud. In this scheme, access policies are being sent in plaintext form which discloses the user privacy and data privacy. Once the ciphertext has been shared among the set of authorized users they would be able to decrypt the ciphertext. Whenever the authorized users are acting as malicious users, they may alter the data and further encrypt and outsource the modified data. It may adversely affect the data owner. In the existing attribute-based encryption scheme, data owner’s authenticity cannot be verified. In order to resolve these problems, we are proposing a novel idea to anonymize the access policy and a signature scheme to verify the authenticity of data as well as that of the data owner. Anonymized access policy never discloses the privacy. The signature scheme is able to detect the insider attack on attribute-based encryption scheme. The proposed system is secure against indistinguishable chosen-ciphertext attack. It is a provably secure and existentially unforgeable access control based data sharing method in the public cloud.     

Accountable privacy preserving attribute-based access control for cloud services enforced using blockchain

International Journal of Information Security - When dealing with cloud services, there are important security requirements that are highly recommended to be achieved, notably, access control....     

基于属性的可净化签名方案

在属性基签名（attribute-based signature, ABS）方案中,签名者密钥由不同的属性生成,只有当所拥有的属性满足给定的签名策略时才能够产生有效签名.验证者不需要知道签名者真实身份就能判断签名是否有效.所以ABS因其匿名性而受到广泛关注.在ABS方案中,一旦密钥发生泄露,那么获得密钥的攻击者就可以生成一个有效签名.原始消息中往往包含一些敏感信息,例如在电子医疗或电子金融场景中,个人的医疗记录或交易记录中包含个人隐私信息,若未经脱敏处理将会导致个人敏感信息泄露.为了解决密钥泄露和敏感信息泄露问题,提出了一种前向安全的高效属性基可净化签名（forward-secure attribute-based sanitizable signature, FABSS）方案.基于η-DHE（η-Diffie-Hellman exponent）困难问题假设,在标准模型下证明了该方案的安全性.提出的方案不仅可以抵抗密钥泄露,保护签名者隐私,同时还具有敏感信息隐藏功能.此外,提出的方案具有固定签名长度,并且在验证阶段只需要计算常数个配对运算.实验分析表明提出方案的性能是高效的.

     

Trust-based privacy preservation for peer-to-peer data sharing

Privacy preservation in a peer-to-peer (P2P) system tries to hide the association between the identity of a participant and the data that it is interested in. This paper proposes a trust-based privacy-preservation method for P2P data sharing. It adopts the trust relation between a peer and its collaborators (buddies). The buddy works as a proxy to send the request and acquire the data. This provides a shield under which the identity of the requester and the accessed data cannot be linked. A privacy measuring method is presented to evaluate the proposed mechanism. Dynamic trust assessment and the enhancement to supplier's privacy are discussed.     

An attribute-based lightweight cloud data access control using hypergraph structure

The Journal of Supercomputing - Cloud file storage systems are the current trend of enterprises and also of individual users. Due to the malicious or unauthorized users, file sharing among the...     

Secure and efficient data collaboration with hierarchical attribute-based encryption in cloud computing

With the increasing trend of outsourcing data to the cloud for efficient data storage, secure data collaboration service including data read and write in cloud computing is urgently required. However, it introduces many new challenges toward data security. The key issue is how to afford secure write operation on ciphertext collaboratively, and the other issues include difficulty in key management and heavy computation overhead on user since cooperative users may read and write data using any device. In this paper, we propose a secure and efficient data collaboration scheme, in which fine-grained access control of ciphertext and secure data writing operation can be afforded based on attribute-based encryption (ABE) and attribute-based signature (ABS) respectively. In order to relieve the attribute authority from heavy key management burden, our scheme employs a full delegation mechanism based on hierarchical attribute-based encryption (HABE). Further, we also propose a partial decryption and signing construction by delegating most of the computation overhead on user to cloud service provider. The security and performance analysis show that our scheme is secure and efficient.     

DyDAP: A dynamic data aggregation scheme for privacy aware wireless sensor networks

End-to-end data aggregation, without degrading sensing accuracy, is a very relevant issue in wireless sensor networks (WSN) that can prevent network congestion to occur. Moreover, privacy management requires that anonymity and data integrity are preserved in such networks. Unfortunately, no integrated solutions have been proposed so far, able to tackle both issues in a unified and general environment. To bridge this gap, in this paper we present an approach for dynamic secure end-to-end data aggregation with privacy function, named DyDAP. It has been designed starting from a UML model that encompasses the most important building blocks of a privacy-aware WSN, including aggregation policies. Furthermore, it introduces an original aggregation algorithm that, using a discrete-time control loop, is able to dynamically handle in-network data fusion to reduce the communication load. The performance of the proposed scheme has been verified using computer simulations, showing that DyDAP avoids network congestion and therefore improves WSN estimation accuracy while, at the same time, guaranteeing anonymity and data integrity.     

混合云环境中多用户数据共享问题研究 *

针对混合云环境多用户数据共享进行了研究,为了完善混合云环境多用户数据共享机制、提高用户存储安全、解决权限撤销延迟问题,此次应用全同态加密算法,并结合门限技术,提出了一个改进的混合云环境多用户数据共享新方案。方案首先对明文进行顺序性分块,之后以改进后的全同态加密算法对明文加密,并发送至混合云存储。方案中为每个共享用户生成等级权限和时间约束信息,实现对共享用户权限管理,同时建立数据完整性标签,验证存储数据的完整性。最后通过实验进行模拟,权限撤销时间小于2s,数据完整性验证中对数据的改变控制在以内,同时访问中增加一个用户只延迟5s。与已有方案相比,表明新方案在实现数据共享的各个方面都获得较好的改善。     

A proxy broadcast re-encryption for cloud data sharing

Proxy re-encryption (PRE) enables a semi-trusted proxy to automatically convert a delegator’s ciphertext to a delegate’s ciphertext without learning anything about the underlying plaintext. PRE schemes have broad applications, such as cloud data sharing systems, distributed file systems, email forward systems and DRM systems. In this paper, we introduced a new notion of proxy broadcast re-encryption (PBRE). In a PBRE scheme, a delegator, Alice, can delegate the decryption right to a set of users at a time, which means that Alice’s ciphertext can be broadcast re-encrypted. We propose a PBRE scheme and prove its security against a chosen-ciphertext attack (CCA) in the random oracle model under the decisional n-BDHE assumption. Furthermore, our scheme is collusion-resistant, which means the proxy cannot collude with a set of delegates to reveal the delegator’s private key.     

Access control aware data retrieval for secret sharing based database outsourcing

Enforcing dynamic and confidential access control policies is a challenging issue of data outsourcing to external servers due to the lack of trust towards the servers. In this paper, we propose a scalable yet flexible access control enforcement mechanism when the underlying relational data, on which access policies are defined, has been shared through a secret sharing scheme. For sharing values of an attribute in a relation, the attribute is assigned a secret distribution key and its values are split and distributed among data servers according to a Shamir based secret sharing scheme. Given access control policies over attributes of the relation schema, access to distribution keys, used further for reconstructing original values, is managed using the Chinese remainder theorem. Our solution, in addition to preserving the confidentiality of access control policies, is flexible to efficiently adopt grant and revoke of authorizations. Moreover, it prevents the possibility of information leakage caused by query processing through an access control aware retrieval of data shares. That is, our solution not only enforces access control policies for reconstructing shares and obtaining original values, but also for retrieving shares in query processing scenario. We implemented our mechanism and performed extensive experiments, whose results confirm its efficiency and considerable scalability in practice.     

Time-variant attribute-based multitype encryption algorithm for improved cloud data security using user profile

The Journal of Supercomputing - Cloud computing becomes more sophisticated to provide different services at different levels of user access. Even though various services are accessed at a different...     

主从链下的物联网隐私数据跨域安全共享模型

为了解决各个信任应用域之间的跨域安全问题,保证隐私数据的跨域共享,利用区块链技术构建了基于主从链的隐私数据跨域共享模型。首先构建了主从链,并提出基于主从链的跨域共享模型架构;设计了基于智能合约的跨域访问机制,并基于跨域访问机制提出了面向隐私数据的跨域安全共享方案;最后,对模型的稳定性、吞吐量、存储开销等方面进行了实验及对比分析。实验结果表明,该模型同最新的单链跨域模型相比,吞吐量提升了270 TPS左右,节点的平均CPU负载和平均内存开销分别下降了24%和64%;同现有多链跨域模型相比,节点的平均CPU负载和平均内存开销分别下降了15%和20%,为物联网隐私数据的跨域安全共享提供了一种有效方法。     

云存储环境下属性基加密综述*

属性基加密作为一种新型的密码方案,将用户私钥和密文与属性相关联,为解决云存储环境下数据安全共享、细粒度访问控制和安全存储等问题提供了一种解决思路。在对密钥策略属性基加密、密文策略属性基加密和混合策略属性基加密深入研究后,根据不同的功能扩展,针对隐藏访问结构、多授权机构、复杂计算安全外包、可搜索加密机制、属性撤销、叛徒追踪等重点难点问题进行了深入探讨研究。最后总结了现有研究工作的不足,并指出了未来的研究方向。     

Outsourcing high-dimensional healthcare data to cloud with personalized privacy preservation

According to the recent rule released by Health and Human Services (HHS), healthcare data can be outsourced to cloud computing services for medical studies. A major concern about outsourcing healthcare data is its associated privacy issues. However, previous solutions have focused on cryptographic techniques which introduce significant cost when applied to healthcare data with high-dimensional sensitive attributes. To address these challenges, we propose a privacy-preserving framework to transit insensitive data to commercial public cloud and the rest to trusted private cloud. Under the framework, we design two protocols to provide personalized privacy protections and defend against potential collusion between the public cloud service provider and the data users. We derive provable privacy guarantees and bounded data distortion to validate the proposed protocols. Extensive experiments over real-world datasets are conducted to demonstrate that the proposed protocols maintain high usability and scale well to large datasets.