基于密文策略属性加密的广电监管数据共享系统

本文设计了一种基于密文策略属性加密（CP-ABE,Ciphertext-Policy Attribute-Based Encryption）的云存储数据共享系统，用于对广电监测监管数据进行加密存储和有条件访问，有效解决了云端数据安全共享和细粒度访问控制的问题，满足防止非法访问及信息泄露的安全需求。     

云存储应用中的加密存储及其检索技术

云计算自身的数据安全问题阻碍其推广应用。通过对数据进行加密可以保护企业及个人用户的数据隐私。对加密数据有效检索难以通过传统信息检索方式实现。文章在分析云存储应用中的存储安全技术基础上,针对加密存储的需求,基于常见的加密检索方法和相关技术,结合自己的研究成果,提出了一种基于全同态加密的检索方法,该方法能在一种程度上提高检索效率。     

面向云存储的安全密文访问控制方案

存储在云端服务器中的敏感数据的保密和安全访问是云存储安全研究的重要内容.针对真实的云存储环境中云服务提供商不可信的情况,采用基于属性的加密算法,提出了一种安全、高效、细粒度的云存储密文访问控制方案.与现有方案相比,该方案在用户撤销时,通过引入广播加密技术,使得撤销用户即使和云服务提供商共谋,也不能对私钥进行更新,保证了数据的安全性;方案将大部分密文重加密和用户私钥更新工作转移给云服务提供商执行,在保证安全性的前提下,降低了数据属主的计算代价;另外该方案还可支持多用户的同时撤销.最后分析了方案的安全性和计算复杂性,并测试了用户撤销时的运行效率.     

基于属性的k次匿名大数据中心访问控制方案

在研究信息服务中心云存储用户的隐私保护问题时,基于属性的加密方案是一种前景看好的解决途径,它有效满足了匿名访问和数据加密等要求。然而,基于属性的加密方案只适用于对云存储服务中加密数据的认证访问。在云计算服务访问控制的环境中,部署这一方案是不切实际的。文章研究大数据中心云存储匿名访问控制的安全需求,介绍基于属性的访问控制方案构成,设计基于属性的k次匿名访问控制安全模型,描述方案的基本原理,给出方案的工作流程,并对方案的安全性和效率进行分析。     

云存储中加密数据的相似检索技术应用研究

随着云存储的广泛应用，大量数据存储在云服务器。尽管云服务提供很多便利，但数据的隐私及安全性一直是重点关注的问题，为解决数据安全问题需要将外储数据以加密的形式进行存储。加密存储的方式保护了数据不被恶意访问，然而数据的一些重要的基本应用如检索等不能实现。为了在不泄露隐私的条件下实现对加密数据的检索，很多可检索的加密方案被提出。然而，这些方案多数只能处理确切的关键字匹配检索而不能进行相似的关键字检索，相似检索在现实应用中又极其重要。本文提出一个高效的支持加密数据相似检索的方案，为了实现相似密文的检索我们利用一种被称为位置敏感的哈希算法。为了确保数据的机密性和安全性，我们给出了严格的安全定义，并且在安全定义下证明了方案的安全性。      

基于f-mOPE的数据库密文检索方案

在云数据库环境下,为保证云存储数据的安全性,通常将数据加密存储。针对加密存储数据查询开销大,不支持密文排序,查询等缺点,该文提出一种 f-mOPE数据库密文检索方案。该方案基于可变保序编码(mOPE),采用二叉排序树数据结构思想,生成明文一一对应的保序编码;基于AES加密方案将数据明文转化为密文存储;采用改进的部分同态加密算法提升保序加密方案的安全性。通过安全性分析及实验结果表明,该方案在保证数据隐私的基础上,不但能抵御统计型攻击,而且能够有效地降低服务器计算开销,提高数据库处理效率。     

支持动态策略更新的半策略隐藏属性加密方案

基于密文策略的属性加密被认为适用于云存储的环境,但当数据拥有者需要更新访问策略时,现有的更新方式因受数据的规模和属性集的大小的限制,会使数据拥有者增加相应的计算开销和通信开销。同时,以明文形式存放在云端的访问策略也会造成用户数据的隐私泄露。针对以上2个问题,提出了一种支持动态策略更新的半策略隐藏属性加密方案,使用所提方案进行策略更新时,用户的计算开销减少,大量的计算由云服务器承担。由于使用了半策略隐藏,用户的具体属性值不会泄露给其他任何第三方,有效保护了用户的隐私。此外,所提方案可以支持任何形式的策略更新,在标准模型下证明了方案是自适应选择明文攻击（CPA）安全的。     

同态加密的发展及应用

认为密码学中的同态加密技术可以为分布式计算环境的用户隐私保护提供强有力的技术支撑。同态加密方案被分成3种类型:部分同态加密、浅同态加密和全同态加密。同态加密方案在分布式计算环境下的密文数据计算方面有着重要的应用,包括:安全云计算与委托计算、远程文件存储、密文检索等。指出目前全同态加密方案的构造还处于理论阶段,尚不能用于实际的密态数据计算问题,如何设计基于代数系统的(自然)全同态加密方案依然是未来研究的重点。     

基于授权的多服务器可搜索密文策略属性基加密方案

针对现有属性基可搜索加密方案缺乏对云服务器授权的服务问题,该文提出一种基于授权的可搜索密文策略属性基加密(CP-ABE)方案。方案通过云过滤服务器、云搜索服务器和云存储服务器协同合作实现搜索服务。用户可将生成的授权信息和陷门信息分别发送给云过滤服务器和云搜索服务器,在不解密密文的情况下,云过滤服务器可对所有密文进行检测。该方案利用多个属性授权机构,在保证数据机密性的前提下能进行高效的细粒度访问,解决数据用户密钥泄露问题,提高数据用户对云端数据的检索效率。通过安全性分析,证明方案在提供数据检索服务的同时无法窃取数据用户的敏感信息,且能够有效地防止数据隐私的泄露。     

面向云存储的高效动态密文访问控制方法

针对云存储中敏感数据的机密性保护问题,在基于属性的加密基础上提出了一种密文访问控制方法HCRE。其思想是设计一种基于秘密共享方案的算法,将访问控制策略变更导致的重加密过程转移到云端执行,从而降低权限管理的复杂度,实现高效的动态密文访问控制。实验分析表明HCRE显著降低了权限管理的时间代价,而且没有向云端泄露额外的信息,保持了数据机密性。     

Efficient Linear Homomorphic Encryption from LWE Over Rings

As the basis for secure public-key encryption under various cases, the learning with errors (LWE) problem has proved to be versatile for encryption schemes. Unfortunately, it tends not to be efficient enough for practical applications. For improving the efficiency issues and quickening the practical applications of the lattice-based public-key cryptosystems, an efficient homomorphic encryption scheme is presented in this paper, which is based on the learning with errors over rings (R-LWE) assumption, and its security is reducible to the hardness of the shortest vector problem in the worst case on ideal lattices. Furthermore, the scheme possesses homomorphism feature that encryption operations are consistent with message operations. The security analysis shows that the proposed encryption scheme is secure against chosen-plaintext attacks in the standard model. At the same time, the efficiency analysis and simulation results indicate that the scheme is much more efficient than previous lattice-based cryptosystems.     

Hybrid cloud approach for block-level deduplication and searchable encryption in large universe

Ciphertext-policy attribute-based searchable encryption (CP-ABSE) can achieve fine-grained access control for data sharing and retrieval, and secure deduplication can save storage space by eliminating duplicate copies. However, there are seldom schemes supporting both searchable encryption and secure deduplication. In this paper, a large universe CP-ABSE scheme supporting secure block-level deduplication are proposed under a hybrid cloud mechanism. In the proposed scheme, after the ciphertext is inserted into bloom filter tree (BFT), private cloud can perform fine-grained deduplication efficiently by matching tags, and public cloud can search efficiently using homomorphic searchable method and keywords matching. Finally, the proposed scheme can achieve privacy under chosen distribution attacks block-level (PRV-CDA-B) secure deduplication and match-concealing (MC) searchable security. Compared with existing schemes, the proposed scheme has the advantage in supporting fine-grained access control, block-level deduplication and efficient search, simultaneously.     

A secure regenerating code‐based cloud storage with efficient integrity verification

Cloud storage is gaining popularity as it relieves the data owners from the burden of data storage and maintenance cost. However, outsourcing data to third‐party cloud servers raise several concerns such as data availability, confidentiality, and integrity. Recently, regenerating codes have gained popularity because of their low repair bandwidth while ensuring data availability. In this paper, we propose a secure regenerating code‐based cloud storage (SRCCS) scheme, which utilizes the verifiable computation property of homomorphic encryption scheme to check the integrity of outsourced data. In this work, an error‐correcting code (ECC)–based homomorphic encryption scheme (HES) is employed to simultaneously provide data privacy as well as error correction while supporting efficient integrity verification. In SRCCS, server regeneration process is initiated on detection of data corruption events in order to ensure data availability. The ECC‐based HES significantly reduces the probability of server regeneration and minimizes the repair cost. Extensive theoretical analysis and simulation results validate the security, efficiency, and practicability of the proposed scheme.     

Attribute-based fully homomorphic encryption scheme over rings

The fully homomorphic encryption has important applications in the area of data security and privacy security of cloud computing,but the size of secret keys and ciphertext in most of current homomorphic encryption schemes were too large,which restricted its practical.To improve these drawbacks,a recoding scheme and a attribute-based encryption scheme based on learning with errors problem over rings were provided,then a attribute-based fully homomorphic encryption was constructed.The new scheme overcame the above mentioned drawbacks,because it did't need public key certificate,meanwhile,it can achieve the fine-grained access control to the ciphertext.Compared with similar results,proposed method decreases the size of keys and ciphertext greatly.     

具有隐私保护的云存储访问控制方案

针对传统的访问控制方案无法在云计算环境下保护用户的属性隐私,提出了具有隐私保护的云存储访问控制方案。采用混合加密体制实现了数据的机密性,即利用对称密钥加密明文数据,再利用公钥密码体制对对称密钥进行加密。在新的访问控制方案中,公钥加密采用了匿名的密文策略下基于属性的加密技术。安全性分析表明,新方案在保护用户属性隐私的同时,达到了选择明文安全性,可抵抗恶意用户及云存储服务器的合谋攻击。     

云计算环境中支持隐私保护的数字版权保护方案简

针对云计算环境中数字内容安全和用户隐私保护的需求,提出了一种云计算环境中支持隐私保护的数字版权保护方案。设计了云计算环境中数字内容版权全生命周期保护和用户隐私保护的框架,包括系统初始化、内容加密、许可授权和内容解密4个主要协议;采用基于属性基加密和加法同态加密算法的内容加密密钥保护和分发机制,保证内容加密密钥的安全性;允许用户匿名向云服务提供商订购内容和申请授权,保护用户的隐私,并且防止云服务提供商、授权服务器和密钥服务器等收集用户使用习惯等敏感信息。与现有的云计算环境中数字版权保护方案相比,该方案在保护内容安全和用户隐私的同时,支持灵活的访问控制,并且支持在线和超级分发应用模式,在云计算环境中具有较好的实用性。     

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.