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。     

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。     

支持属性撤销的可验证多关键词搜索加密方案

近年来,可搜索加密技术及细粒度访问控制的属性加密在云存储环境下得到广泛应用。考虑到现存的基于属性的可搜索加密方案存在仅支持单关键词搜索而不支持属性撤销的问题,以及单关键词搜索可能造成返回搜索结果部分错误并导致计算和宽带资源浪费的缺陷,该文提出一种支持属性撤销的可验证多关键词搜索加密方案。该方案允许用户检测云服务器搜索结果的正确性,同时在细粒度访问控制结构中支持用户属性的撤销,且在属性撤销过程中不需要更新密钥和重加密密文。该文在随机预言机模型下基于判定性线性假设被证明具有抵抗选择关键词集攻击安全性及关键词隐私性,同时从理论和实验两方面分析验证了该方案具有较高的计算效率与存储效率。     

云计算平台下基于属性加密的动态版权使用控制方案（英文）

In order to achieve fine-grained access control in cloud computing,existing digital rights management(DRM) schemes adopt attribute-based encryption as the main encryption primitive.However,these schemes suffer from inefficiency and cannot support dynamic updating of usage rights stored in the cloud.In this paper,we propose a novel DRM scheme with secure key management and dynamic usage control in cloud computing.We present a secure key management mechanism based on attribute-based encryption and proxy re-encryption.Only the users whose attributes satisfy the access policy of the encrypted content and who have effective usage rights can be able to recover the content encryption key and further decrypt the content.The attribute based mechanism allows the content provider to selectively provide fine-grained access control of contents among a set of users,and also enables the license server to implement immediate attribute and user revocation.Moreover,our scheme supports privacy-preserving dynamic usage control based on additive homomorphic encryption,which allows the license server in the cloud to update the users' usage rights dynamically without disclosing the plaintext.Extensive analytical results indicate that our proposed scheme is secure and efficient.     

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.     

Research on cloud storage systems supporting secure sharing

A practical scheme for the cloud storage system was proposed to ensure security and efficiency during data sharing.The scheme which combine attribute-based encryption,proxy encryption with symmetric encryption,could integrate access control,efficient search with encryption well together.The scheme archived conjunctive-keyword non-field subset search by using bilinear mapping and polynomial equation.The scheme reduced the cost of decryption by outsourcing most of the decryption operations from the terminal to the cloud.At last,the performance was analyzed and an experiment was made for verification.     

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。     

基于区块链的结果可追溯的可搜索加密方案

在可搜索加密方案中,无论是云端服务器还是用户,都可能存在欺骗行为。为了解决这种安全问题,给出公平性安全的定义,提出基于区块链的可搜索加密方案。通过第三方可信机构（trusted authority,TA）验证数据传输过程中数据的一致性,区块链记录完整验证结果以防止篡改,使所涉及的实体达成一致的安全共识,从而实现公平性安全。安全性与复杂性分析表明,该方案是可行的。当该方案与搜索结果可验证的可搜索加密方案相结合时,可优化成基于区块链的搜索结果可验证的可搜索加密方案,其安全性将得到进一步的提高。     

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.     

基于区块链的公钥可搜索加密方案

针对公钥加密方案的陷门安全问题,引入随机数构造陷门与索引,用于抵御来自服务器内部的关键字猜测攻击,避免因服务器好奇行为带来的数据泄露。对第三方的可信问题进行研究,将区块链技术与可搜索加密方案相结合,使用智能合约作为可信第三方进行检索工作,既可以防止服务器内部的关键字猜测攻击,又可以保证检索结果的正确性,从而限制服务器在下发数据时的恶意行为。通过安全性分析,验证了所提方案满足IND-KGA安全性。经过与其他方案进行实验对比,证明了所提方案在时间开销上具有一定的优势。     

基于区块链的多关键词模糊搜索加密方案

针对1对多数据密文共享中多关键词模糊匹配和用户公平性问题,该文提出一种基于区块链的多关键词模糊搜索加密方案。该文提出一种R-HashMap索引结构,通过使用对偶编码函数和位置敏感哈希函数来构建安全索引,并采用K最近邻算法来加密索引,通过计算欧式距离度量查询关键词向量与索引节点之间的相似性,实现多关键词模糊密文搜索。该文除了消除预定义词典和降低存储开销外,还在不增加搜索复杂度的前提下实现对安全索引的更新。此外,将以太坊区块链技术与可搜索加密方案相结合避免了恶意服务器对数据的篡改,使用智能合约作为可信第三方进行检索工作,不仅可以防止云服务器内部的关键词猜测攻击,还可以解决检索结果不正确的问题。通过安全性证明分析,该文不但满足自适应选择关键词语义安全性,还可以保护用户隐私和数据安全。将该文与其他方案进行实验对比,证明该文在保证精确度的前提下,时间开销上具有更好的效率优势。     

智慧医疗中基于属性加密的云存储数据共享

在电子病历系统中,为了实现多用户环境下的数据搜索,该文提出一种属性基可搜索加密方案。该文将密文和安全索引存储在医疗云,当用户请求医疗数据时,利用属性基可搜索加密算法进行数据搜索,实现了细粒度访问控制。同时方案引入了密文验证算法,解决了半诚实且好奇的云服务器模型下搜索结果不正确的问题。利用数据去重技术实现了重复数据的消除,减少占用医疗云的存储空间。方案同时实现了访问策略的隐藏,保证了数据用户的隐私安全。安全性分析表明,所提方案能很好地保护用户的隐私以及数据的安全。性能分析表明,该方案具有较好的性能,更加适用于智慧医疗等多对多应用场景,有效实现了医生和第三方数据用户在不侵犯患者隐私的前提下共享患者电子病历。     

区块链上基于云辅助的密文策略属性基数据共享加密方案

针对云存储的集中化带来的数据安全和隐私保护问题,该文提出一种区块链上基于云辅助的密文策略属性基(CP-ABE)数据共享加密方案。该方案采用基于属性加密技术对加密数据文件的对称密钥进行加密,并上传到云服务器,实现了数据安全以及细粒度访问控制;采用可搜索加密技术对关键字进行加密,并将关键字密文上传到区块链(BC)中,由区块链进行关键字搜索保证了关键字密文的安全,有效地解决现有的云存储共享系统所存在的安全问题。该方案能够满足选择明文攻击下的不可区分性、陷门不可区分性和抗串联性。最后,通过性能评估,验证了该方案的有效性。     

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.     

权限分离的属性基加密数据共享方案

属性基加密(ABE, attribute-based encryption)用于提供细粒度访问控制及一对多加密,现已被广泛应用于分布式环境下数据共享方案以提供隐私保护。然而,现有的属性基加密数据共享方案均允许数据拥有者任意修改数据,导致数据真实性无法保证,经常难以满足一些实际应用需求,如个人电子病例、审核系统、考勤系统等。为此,提出一种能保证数据真实可靠且访问控制灵活的数据共享方案。首先,基于RSA代理加密技术实现读写权限分离机制以保证数据真实可靠;其次,使用属性基加密机制提供灵活的访问控制策略;最后,利用关键字检索技术实现支持密钥更新的高效撤销机制。详细的安全性分析表明本方案能提供数据机密性以实现隐私保护,且性能分析和仿真表明本方案具有较高效率,能有效满足实际应用需求。     

具有隐私保护的细粒度智能家居远程数据安全更新方案

针对现存智能家居软件更新方案中存在的粗粒度访问控制、单点服务失效、用户解密效率低下等问题,该文提出一种具有隐私保护的细粒度智能家居远程数据安全更新方案。该方案通过属性基加密技术实现了细粒度访问控制,并结合区块链和星际文件系统(IPFS)技术对数据进行存储。通过对访问策略进行隐藏,构造出一种策略隐藏的密文策略基于属性加密(CP-ABE)算法,进一步保护了用户的隐私。此外,通过设计面向轻量级用户的外包解密算法,所提方案有效减轻了轻量级用户的计算负担,并结合区块链和智能合约技术实现了外包解密过程的公平支付。最后,基于判定的双线性迪菲赫尔曼 (DBDH)假设,证明了所提方案是选择明文攻击下的不可区分 (IND-CPA)安全的。仿真实验结果表明,所提方案与现有方案相比终端用户解密成本和通信开销明显降低。     

Attribute-based encryption scheme supporting attribute revocation in cloud storage environment

Attribute-based encryption (ABE) scheme is widely used in the cloud storage due to its fine-grained access control.Each attribute in ABE may be shared by multiple users at the same time.Therefore,how to achieve attribute-level user revocation is currently facing an important challenge.Through research,it has been found that some attribute-level user revocation schemes currently can’t resist the collusion attack between the revoked user and the existing user.To solve this problem,an attribute-based encryption scheme that supported the immediate attribute revocation was proposed.The scheme could achieve attribute-level user revocation and could effectively resist collusion attacks between the revoked users and the existing users.At the same time,this scheme outsourced complex decryption calculations to cloud service providers with powerful computing ability,which reduced the computational burden of the data user.The scheme was proved secure based on computational Diffie-Hellman assumption in the standard model.Finally,the functionality and efficiency of the proposed scheme were analyzed and verified.The experimental results show that the proposed scheme can safely implement attribute-level user revocation and has the ability to quickly decrypt,which greatly improves the system efficiency.     

Multi-authority attribute-based encryption with efficient revocation

Multi-authority attribute-based encryption was very suitable for data access control in a cloud storage environment.However,efficient user revocation in multi-authority attribute-based encryption remains a challenging problem that prevents it from practical applications.A multi-authority ciphertext-policy attribute-based encryption scheme with efficient revocation was proposed in prime order bilinear groups,and was further proved statically secure and revocable in the random oracle model.Extensive efficiency analysis results indicate that the proposed scheme significantly reduce the computation cost for the users.In addition,the proposed scheme supports large universe and any monotone access structures,which makes it more flexible for practical applications.     

面向敏感数据共享环境下的融合访问控制机制

为解决敏感数据共享应用中的数据分发问题和提高数据共享的安全性,将属性基加密机制和使用控制技术相结合,提出一种融合访问控制机制。该机制一方面采用属性基加密机制保证了数据在存储和分发过程中的机密性,通过灵活且可扩展的访问控制策略控制敏感数据的共享范围;另一方面,通过使用控制技术实现对用户的权限控制,防止合法用户对敏感数据进行非法操作,解决共享用户中的权限滥用问题。最后,对机制的安全性和性能进行了分析,显著地降低了服务端的工作负荷,并通过实验测试了该机制的有效性。     

Attribute-based proxy re-encryption scheme with multiple features

A ideal proxy re-encryption scheme has five features,such as one-way encryption,non-interaction,repeatability,controllability and verifiability.The existing schemes,however,have only two or three of the five features,which reduces the utility of them to some extent.For this,a new ciphertext-policy attribute-based proxy re-encryption (CP-ABPRE) scheme with the above five features was proposed.In the proposed scheme,the cloud proxy server could only re-encrypt the ciphertext specified by the delegator by using the re-encryption key,and resist the collusion attack between the user and the proxy satisfying the re-encryption sharing policy.Most of encryption and decryption were outsourced to cloud servers so that it reduced the computing burden on the user’s client.The security analysis show that the proposed scheme resists the selective chosen plaintext attack (SCPA).