The cloud allows clients to store and share data.Depending on the user’s needs,it is imperative to design an effective access control plan to share the information only with approved users.The user loses control of t...The cloud allows clients to store and share data.Depending on the user’s needs,it is imperative to design an effective access control plan to share the information only with approved users.The user loses control of their data when the data is outsourced to the cloud.Therefore,access control mechanisms will become a significant challenging problem.The Ciphertext-Policy Attribute-Based Encryption(CP-ABE)is an essential solution in which the user can control data access.CP-ABE encrypts the data under a limited access policy after the user sets some access policies.The user can decrypt the data if they satisfy the limited access policy.Although CP-ABE is an effective access control program,the privacy of the policy might be compromised by the attackers.Namely,the attackers can gather important information from plain text policy.To address this issue,the SHA-512 algorithm is presented to create a hash code for the user’s attributes in this paper.Depending on the created hash codes,an access policy will be formed.It leads to protecting the access policy against attacks.The effectiveness of the proposed scheme is assessed based on decryption time,private key generation time,ciphertext generation time,and data verification time.展开更多
A novel broadcast encryption scheme for group communication scenarios in distributed networks is presented. In the scheme, anyone is allowed to encrypt a message and distribute it to a designated group. Each member in...A novel broadcast encryption scheme for group communication scenarios in distributed networks is presented. In the scheme, anyone is allowed to encrypt a message and distribute it to a designated group. Each member in the designated group has the ability to independently decrypt a ciphertext. In contrast to traditional broadcast encryption, all the valid receivers in the proposed scheme compose the designated group. To take advantage of this property, a tab for the group is set and the matching private key for each member is generated. In addition, before decrypting a ciphertext, anyone in the scheme can verify the ciphertext, to ensure that the ciphertext is correct. This property is very important for large-scale group communication, as the gateway can filter incorrect ciphertext and alleviate the receiver's workload. Finally, a proof in the random oracle model is given, to show that the proposed scheme is secure against the adaptively chosen ciphertext attack.展开更多
Strong security in public key cryptography is not enongh; the encryption has to be achieved in an efficient way. OAEP or SAEP is only suitable for special applications (e. g. key transport), and securely transportin...Strong security in public key cryptography is not enongh; the encryption has to be achieved in an efficient way. OAEP or SAEP is only suitable for special applications (e. g. key transport), and securely transporting message of any length is a challenge. Motivated by the hybrid encryption, we present a practical approach to achieve the (adaptively) chosen eiphertext security. The time cost of encryption/decryption of proposed scheme is similar to OAEP and the bandwidth of message recovery is 92% for standard security parameter, while RSA-OAEP is 84%. The scheme is also provably secure against adaptively chosen ciphertext attacks in the random oracle model. We conclude that the approach is practical in more extensive application.展开更多
As the use of cloud storage for various services increases,the amount of private personal information along with data stored in the cloud storage is also increasing.To remotely use the data stored on the cloud storage...As the use of cloud storage for various services increases,the amount of private personal information along with data stored in the cloud storage is also increasing.To remotely use the data stored on the cloud storage,the data to be stored needs to be encrypted for this reason.Since“searchable encryption”is enable to search on the encrypted data without any decryption,it is one of convenient solutions for secure data management.A public key encryption with keyword search(for short,PEKS)is one of searchable encryptions.Abdalla et al.firstly defined IND-CCA security for PEKS to enhance it’s security and proposed consistent IND-CCA secure PEKS based on the“robust”ANO-CCA secure identity-based encryption(IBE).In this paper,we propose two generic constructions of consistent IND-CCA secure PEKS combining(1)a hierarchical identity based encryption(for short,HIBE)and a signature scheme or(2)a HIBE,an encapsulation,and a message authentication code(for short,MAC)scheme.Our generic constructions identify that HIBE requires the security of a signature or a MAC as well as the weaker“ANO-CPA security(resp.,IND-CPA security)”of HIBE than“ANOCCA security(resp.,IND-CCA security)”of IBE required in for achieving IND-CCA secure(resp.,consistent)PEKS.Finally,we prove that our generic constructions satisfy IND-CCA security and consistency under the security models.展开更多
In most existing CP-ABE schemes, there is only one authority in the system and all the public keys and private keys are issued by this authority, which incurs ciphertext size and computation costs in the encryption an...In most existing CP-ABE schemes, there is only one authority in the system and all the public keys and private keys are issued by this authority, which incurs ciphertext size and computation costs in the encryption and decryption operations that depend at least linearly on the number of attributes involved in the access policy. We propose an efficient multi-authority CP-ABE scheme in which the authorities need not interact to generate public information during the system initialization phase. Our scheme has constant ciphertext length and a constant number of pairing computations. Our scheme can be proven CPA-secure in random oracle model under the decision q-BDHE assumption. When user's attributes revocation occurs, the scheme transfers most re-encryption work to the cloud service provider, reducing the data owner's computational cost on the premise of security. Finally the analysis and simulation result show that the schemes proposed in this thesis ensure the privacy and secure access of sensitive data stored in the cloud server, and be able to cope with the dynamic changes of users' access privileges in large-scale systems. Besides, the multi-authority ABE eliminates the key escrow problem, achieves the length of ciphertext optimization and enhances the effi ciency of the encryption and decryption operations.展开更多
Proxy re-encryption(PRE)allows users to transfer decryption rights to the data requester via proxy.Due to the current PRE schemes from lattice(LPRE)cannot fulfill chosen-ciphertext attack(CCA)security,an identity-base...Proxy re-encryption(PRE)allows users to transfer decryption rights to the data requester via proxy.Due to the current PRE schemes from lattice(LPRE)cannot fulfill chosen-ciphertext attack(CCA)security,an identity-based PRE(IB-PRE)scheme from learning with errors over ring(RLWE)assumption with ciphertext evolution(IB-LPRE-CE)was proposed.IB-LPRE-CE generates the private key using the preimage sampling algorithm(SamplePre)and completes the ciphertext delegation using the re-encryption algorithm.In addition,for the problem of ciphertext delegation change caused by the long-term secret key update,the idea of PRE is used to complete ciphertext evolution and the modification of ciphertext delegation,which improves the efficiency of secure data sharing.In terms of security,IB-LPRE-CE is CCA security based on RLWE assumption.Compared with the current LPRE schemes,IB-LPRE-CE offers greater security and improves the computational efficiency of the encryption algorithm.展开更多
For leakage-resilient ciphertext-policy attribute-based encryption (CP-ABE) at present, the size of the ciphertexts in most of them relies on the number of attributes. How to overcome this shortcoming is a challenge...For leakage-resilient ciphertext-policy attribute-based encryption (CP-ABE) at present, the size of the ciphertexts in most of them relies on the number of attributes. How to overcome this shortcoming is a challenge problem. Based on the Goldreich-Levin theorem and dual system encryption, an efficient CP-ABE scheme with constant size ciphertexts is proposed in this paper. It can tolerate leakage on master secret key and attribute-based secret keys with auxiliary inputs. Furthermore, the proposed scheme can be realized as resilience against continual leakage if keys are periodically updated. Under some static assumptions instead of other strong assumptions, the introduced scheme achieves adaptively security in the standard model.展开更多
在定位请求服务中,如何保护用户的位置隐私和位置服务提供商(Localization service provider,LSP)的数据隐私是关系到WiFi指纹定位应用的一个具有挑战性的问题。基于密文域的K-近邻(K-nearest neighbors,KNN)检索,本文提出了一种适用于...在定位请求服务中,如何保护用户的位置隐私和位置服务提供商(Localization service provider,LSP)的数据隐私是关系到WiFi指纹定位应用的一个具有挑战性的问题。基于密文域的K-近邻(K-nearest neighbors,KNN)检索,本文提出了一种适用于三方的定位隐私保护算法,能有效提升对LSP指纹信息隐私的保护强度并降低计算开销。服务器和用户分别完成对指纹信息和定位请求的加密,而第三方则基于加密指纹库和加密定位请求,在隐私状态下完成对用户的位置估计。所提算法把各参考点的位置信息随机嵌入指纹,可避免恶意用户获取各参考点的具体位置;进一步利用布隆滤波器在隐藏接入点信息的情况下,第三方可完成参考点的在线匹配,实现对用户隐私状态下的粗定位,可与定位算法结合降低计算开销。在公共数据集和实验室数据集中,对两种算法的安全、开销和定位性能进行了全面的评估。与同类加密算法比较,在不降低定位精度的情况下,进一步增强了对数据隐私的保护。展开更多
密文策略属性基加密(ciphertext-policy attribute-based encryption,CP-ABE)技术可以在保证数据隐私性的同时提供细粒度访问控制.针对现有的基于CP-ABE的访问控制方案不能有效解决边缘计算环境中的关键数据安全问题,提出一种边缘计算...密文策略属性基加密(ciphertext-policy attribute-based encryption,CP-ABE)技术可以在保证数据隐私性的同时提供细粒度访问控制.针对现有的基于CP-ABE的访问控制方案不能有效解决边缘计算环境中的关键数据安全问题,提出一种边缘计算环境中基于区块链的轻量级密文访问控制方案(blockchain-based lightweight access control scheme over ciphertext in edge computing,BLAC).在BLAC中,设计了一种基于椭圆曲线密码的轻量级CP-ABE算法,使用快速的椭圆曲线标量乘法实现算法加解密功能,并将大部分加解密操作安全地转移,使得计算能力受限的用户设备在边缘服务器的协助下能够高效地完成密文数据的细粒度访问控制;同时,设计了一种基于区块链的分布式密钥管理方法,通过区块链使得多个边缘服务器能够协同地为用户分发私钥.安全性分析和性能评估表明BLAC能够保障数据机密性,抵抗共谋攻击,支持前向安全性,具有较高的用户端计算效率,以及较低的服务器端解密开销和存储开销.展开更多
To give concurrent consideration both the efficiency and the security(intensity of intractable problem) in the standard model,a chosen ciphertext secure identity-based broadcast encryption is proposed.Against the chos...To give concurrent consideration both the efficiency and the security(intensity of intractable problem) in the standard model,a chosen ciphertext secure identity-based broadcast encryption is proposed.Against the chosen ciphertext security model,by using identity(ID) sequence and adding additional information in ciphertext,the self-adaptive chosen identity security(the full security) and the chosen ciphertext security are gained simultaneously.The reduction of scheme's security is the decisional bilinear Diffie-Hellman(BDH) intractable assumption,and the proof of security shows that the proposed scheme is indistinguishable against adaptive chosen ciphertext attacks in the standard model under the decisional BDH intractable assumption.So the security level is improved,and it is suitable for higher security environment.展开更多
文摘The cloud allows clients to store and share data.Depending on the user’s needs,it is imperative to design an effective access control plan to share the information only with approved users.The user loses control of their data when the data is outsourced to the cloud.Therefore,access control mechanisms will become a significant challenging problem.The Ciphertext-Policy Attribute-Based Encryption(CP-ABE)is an essential solution in which the user can control data access.CP-ABE encrypts the data under a limited access policy after the user sets some access policies.The user can decrypt the data if they satisfy the limited access policy.Although CP-ABE is an effective access control program,the privacy of the policy might be compromised by the attackers.Namely,the attackers can gather important information from plain text policy.To address this issue,the SHA-512 algorithm is presented to create a hash code for the user’s attributes in this paper.Depending on the created hash codes,an access policy will be formed.It leads to protecting the access policy against attacks.The effectiveness of the proposed scheme is assessed based on decryption time,private key generation time,ciphertext generation time,and data verification time.
文摘A novel broadcast encryption scheme for group communication scenarios in distributed networks is presented. In the scheme, anyone is allowed to encrypt a message and distribute it to a designated group. Each member in the designated group has the ability to independently decrypt a ciphertext. In contrast to traditional broadcast encryption, all the valid receivers in the proposed scheme compose the designated group. To take advantage of this property, a tab for the group is set and the matching private key for each member is generated. In addition, before decrypting a ciphertext, anyone in the scheme can verify the ciphertext, to ensure that the ciphertext is correct. This property is very important for large-scale group communication, as the gateway can filter incorrect ciphertext and alleviate the receiver's workload. Finally, a proof in the random oracle model is given, to show that the proposed scheme is secure against the adaptively chosen ciphertext attack.
基金Supported by the National Natural Science Foun-dation of China (60403027)
文摘Strong security in public key cryptography is not enongh; the encryption has to be achieved in an efficient way. OAEP or SAEP is only suitable for special applications (e. g. key transport), and securely transporting message of any length is a challenge. Motivated by the hybrid encryption, we present a practical approach to achieve the (adaptively) chosen eiphertext security. The time cost of encryption/decryption of proposed scheme is similar to OAEP and the bandwidth of message recovery is 92% for standard security parameter, while RSA-OAEP is 84%. The scheme is also provably secure against adaptively chosen ciphertext attacks in the random oracle model. We conclude that the approach is practical in more extensive application.
文摘As the use of cloud storage for various services increases,the amount of private personal information along with data stored in the cloud storage is also increasing.To remotely use the data stored on the cloud storage,the data to be stored needs to be encrypted for this reason.Since“searchable encryption”is enable to search on the encrypted data without any decryption,it is one of convenient solutions for secure data management.A public key encryption with keyword search(for short,PEKS)is one of searchable encryptions.Abdalla et al.firstly defined IND-CCA security for PEKS to enhance it’s security and proposed consistent IND-CCA secure PEKS based on the“robust”ANO-CCA secure identity-based encryption(IBE).In this paper,we propose two generic constructions of consistent IND-CCA secure PEKS combining(1)a hierarchical identity based encryption(for short,HIBE)and a signature scheme or(2)a HIBE,an encapsulation,and a message authentication code(for short,MAC)scheme.Our generic constructions identify that HIBE requires the security of a signature or a MAC as well as the weaker“ANO-CPA security(resp.,IND-CPA security)”of HIBE than“ANOCCA security(resp.,IND-CCA security)”of IBE required in for achieving IND-CCA secure(resp.,consistent)PEKS.Finally,we prove that our generic constructions satisfy IND-CCA security and consistency under the security models.
基金supported by National Natural Science Foundation of China under Grant No.60873231Natural Science Foundation of Jiangsu Province under Grant No.BK2009426+1 种基金Major State Basic Research Development Program of China under Grant No.2011CB302903Key University Science Research Project of Jiangsu Province under Grant No.11KJA520002
文摘In most existing CP-ABE schemes, there is only one authority in the system and all the public keys and private keys are issued by this authority, which incurs ciphertext size and computation costs in the encryption and decryption operations that depend at least linearly on the number of attributes involved in the access policy. We propose an efficient multi-authority CP-ABE scheme in which the authorities need not interact to generate public information during the system initialization phase. Our scheme has constant ciphertext length and a constant number of pairing computations. Our scheme can be proven CPA-secure in random oracle model under the decision q-BDHE assumption. When user's attributes revocation occurs, the scheme transfers most re-encryption work to the cloud service provider, reducing the data owner's computational cost on the premise of security. Finally the analysis and simulation result show that the schemes proposed in this thesis ensure the privacy and secure access of sensitive data stored in the cloud server, and be able to cope with the dynamic changes of users' access privileges in large-scale systems. Besides, the multi-authority ABE eliminates the key escrow problem, achieves the length of ciphertext optimization and enhances the effi ciency of the encryption and decryption operations.
基金the National Natural Science Foundation of China under Grant,the Fundamental Research Funds for the Central Universities under Grant No.FRF-TP-14-046A2
基金supported by the Henan Key Laboratory of Network Cryptography Technology(LNCT2022-A11)the Shaanxi Key Laboratory of Information Communication Network and Security(ICNS202006)。
文摘Proxy re-encryption(PRE)allows users to transfer decryption rights to the data requester via proxy.Due to the current PRE schemes from lattice(LPRE)cannot fulfill chosen-ciphertext attack(CCA)security,an identity-based PRE(IB-PRE)scheme from learning with errors over ring(RLWE)assumption with ciphertext evolution(IB-LPRE-CE)was proposed.IB-LPRE-CE generates the private key using the preimage sampling algorithm(SamplePre)and completes the ciphertext delegation using the re-encryption algorithm.In addition,for the problem of ciphertext delegation change caused by the long-term secret key update,the idea of PRE is used to complete ciphertext evolution and the modification of ciphertext delegation,which improves the efficiency of secure data sharing.In terms of security,IB-LPRE-CE is CCA security based on RLWE assumption.Compared with the current LPRE schemes,IB-LPRE-CE offers greater security and improves the computational efficiency of the encryption algorithm.
基金supported in part by the Nature Science Foundation of China (61472307, 61402112, 61100165, 61100231)Natural Science Basic Research Plan in Shaanxi Province of China (2016JM6004)
文摘For leakage-resilient ciphertext-policy attribute-based encryption (CP-ABE) at present, the size of the ciphertexts in most of them relies on the number of attributes. How to overcome this shortcoming is a challenge problem. Based on the Goldreich-Levin theorem and dual system encryption, an efficient CP-ABE scheme with constant size ciphertexts is proposed in this paper. It can tolerate leakage on master secret key and attribute-based secret keys with auxiliary inputs. Furthermore, the proposed scheme can be realized as resilience against continual leakage if keys are periodically updated. Under some static assumptions instead of other strong assumptions, the introduced scheme achieves adaptively security in the standard model.
文摘在定位请求服务中,如何保护用户的位置隐私和位置服务提供商(Localization service provider,LSP)的数据隐私是关系到WiFi指纹定位应用的一个具有挑战性的问题。基于密文域的K-近邻(K-nearest neighbors,KNN)检索,本文提出了一种适用于三方的定位隐私保护算法,能有效提升对LSP指纹信息隐私的保护强度并降低计算开销。服务器和用户分别完成对指纹信息和定位请求的加密,而第三方则基于加密指纹库和加密定位请求,在隐私状态下完成对用户的位置估计。所提算法把各参考点的位置信息随机嵌入指纹,可避免恶意用户获取各参考点的具体位置;进一步利用布隆滤波器在隐藏接入点信息的情况下,第三方可完成参考点的在线匹配,实现对用户隐私状态下的粗定位,可与定位算法结合降低计算开销。在公共数据集和实验室数据集中,对两种算法的安全、开销和定位性能进行了全面的评估。与同类加密算法比较,在不降低定位精度的情况下,进一步增强了对数据隐私的保护。
文摘密文策略属性基加密(ciphertext-policy attribute-based encryption,CP-ABE)技术可以在保证数据隐私性的同时提供细粒度访问控制.针对现有的基于CP-ABE的访问控制方案不能有效解决边缘计算环境中的关键数据安全问题,提出一种边缘计算环境中基于区块链的轻量级密文访问控制方案(blockchain-based lightweight access control scheme over ciphertext in edge computing,BLAC).在BLAC中,设计了一种基于椭圆曲线密码的轻量级CP-ABE算法,使用快速的椭圆曲线标量乘法实现算法加解密功能,并将大部分加解密操作安全地转移,使得计算能力受限的用户设备在边缘服务器的协助下能够高效地完成密文数据的细粒度访问控制;同时,设计了一种基于区块链的分布式密钥管理方法,通过区块链使得多个边缘服务器能够协同地为用户分发私钥.安全性分析和性能评估表明BLAC能够保障数据机密性,抵抗共谋攻击,支持前向安全性,具有较高的用户端计算效率,以及较低的服务器端解密开销和存储开销.
基金the National Natural Science Foundation of China (No.60970119)the National Basic Research Program (973) of China (No.2007CB311201)
文摘To give concurrent consideration both the efficiency and the security(intensity of intractable problem) in the standard model,a chosen ciphertext secure identity-based broadcast encryption is proposed.Against the chosen ciphertext security model,by using identity(ID) sequence and adding additional information in ciphertext,the self-adaptive chosen identity security(the full security) and the chosen ciphertext security are gained simultaneously.The reduction of scheme's security is the decisional bilinear Diffie-Hellman(BDH) intractable assumption,and the proof of security shows that the proposed scheme is indistinguishable against adaptive chosen ciphertext attacks in the standard model under the decisional BDH intractable assumption.So the security level is improved,and it is suitable for higher security environment.