Bilinear Diffie-Hellman Research Articles

Providing a Secure Cloud Storage by Using Attribute Based Temporary Key Word Search Scheme

The cloud providers are not fully trusted in the accept of temporary keyword search on confidential data. Hence this is the main focus of this research, it is necessary to outsource data in the encrypted format. In the attribute-based keyword search scheme the authorized users generate some tokens which were in encrypted format and send them to cloud for the search operation. These tokens can be used to extract all the cipher texts which are generated at any time and contain the search token which were generated by authorized users. Since this may lead to some information leakage, a new cryptographic primitive is introduced which is more secure to propose a scheme in which the search tokens can only extract the cipher texts generated in a specified time interval and that cryptographic primitive is called key-policy attribute-based temporary keyword search (KPABTKS) which provide this property. To evaluate the security, we have to prove that the proposed scheme achieves the keyword secrecy property and is secure against selectively chosen keyword attack (SCKA) both in the random oracle model and Decisional Bilinear Diffie-Hellman (DBDH) assumption. And at last the research will show the complexity of the encryption algorithm is linear with respect to the number of the involved attributes.

Certificateless public key encryption with conjunctive keyword search and its application to cloud-based reliable smart grid system

A public key encryption scheme with conjunctive keyword search allows a semi-trusted third party (or a cloud server) to search over an encrypted data after receiving a trapdoor generated from a conjunctive keyword set. Assume that a sender sends a number of data to a receiver and those data are all stored in the same cloud server. Normally, if the receiver uses one keyword or separate keywords to look for through hundreds of data, it might get in return a huge number of associated data and most of them are unwanted. In this paper, we design a new certificateless public key encryption scheme with conjunctive keyword search, which only returns the desired data. We also prove that the designed scheme is secure against adaptive chosen keyword attacks in the random oracle model under bilinear Diffie-Hellman (BDH) problem assumption. Experimental results show that our scheme has better performance during the testing phase and has a lower communication cost than two related schemes. The comparison about security properties also shows that our scheme is more secure than them. Finally, we give an application example of our scheme in a cloud-based reliable smart grid system.

Heterogeneous deniable authentication and its application to e-voting systems

An electronic voting (e-voting) system allows voters to cast their votes secretly and securely over a public channel. Security is the critical issue that should be considered in such a system. In this paper, we propose a heterogeneous deniable authentication (HDA) protocol for e-voting systems. The proposed protocol allows a sender in a certificateless cryptography (CLC) environment to transmit a message to a receiver in a public key infrastructure (PKI)environment. Our protocol admits security proof in the random oracle model under the bilinear Diffie–Hellman (BDH) and computational Diffie–Hellman (CDH) assumptions. Additionally, our protocol provides batch verification, which can accelerate the verification of authenticators. Comprehensive analysis shows that our protocol is highly suitable for practical e-voting systems.

Flexible and Efficient Authenticated Key Agreement Scheme for BANs Based on Physiological Features

In Body Area Networks (BANs), bio-sensors can collect personal health information and cooperate with each other to provide intelligent health care services for medical users. Since personal health information is highly privacy-sensitive, the flourish of BANs still faces critical security challenges, especially secure communication between bio-sensors. In this paper, we propose a flexible and efficient authenticated key agreement scheme (PBAKA) to provide secure communication for BANs. Specifically, we employ a control unit (e.g., smart phone) to launch authentication based on physiological features collected from BANs, and integrate bilinear pairings to negotiate session keys for bio-sensors. Since physiological features can be collected from various kinds of bio-sensors in real time, PBAKA is flexible for adding new bio-sensors without pre-distributed keys. Meanwhile, PBAKA is computationally efficient by offloading authentication burden from resource-limited bio-sensors to the control unit. Security analysis demonstrates that PBAKA is provably secure under the decisional bilinear Diffie-Hellman assumption. Extensive experimental results validate efficient communication, computation and energy consumption of our scheme when compared with several existing solutions.

Improving the proof of "Privacy-preserving attribute-keyword based data publish-subscribe service on cloud platforms".

Most recently, Kan Yang et al. proposed an attribute-keyword based encryption scheme for data publish-subscribe service(AKPS), which is highly useful for cloud storage scenario. Unfortunately, we discover that there is a flaw in the security proof of indistinguishability of the tag and trapdoor against chosen keyword attack under the Bilinear Diffie-Hellman (BDH) assumption. As the security proof is a key component for a cryptographic scheme, based on the Decisional Diffie-Hellman (DDH) assumption, we improve the security proof method and give a new security proof of the AKPS scheme for indistinguishability of the tag and trapdoor in our proposal, which is more rigorous than the original one. Furthermore, we also demonstrate that the AKPS scheme is secure against data Replayable Chosen Ciphertext Attack (RCCA).

An authenticated hierarchical asymmetric group key agreement protocol based on identity

Asymmetric group key agreement protocol is to negotiate a shared group encryption key. Each member can calculate a decryption key corresponding to the encryption key. With the rapid development of network and system technology, secure information exchange has been one of the foci. In this paper, we propose an authenticated hierarchical asymmetric group key agreement protocol based on identity. Based on the realisation of a round of asymmetric group key agreement, the protocol carries out a second round of agreement. Different levels of secrets exchange information between a group of players with different permissions as the number of rounds increases, which can achieve anonymity and authentication and support dynamic group key updating of nodes to achieve forward and backward security of group key. The protocol proved to be secure under the assumption of bilinear computational Diffie-Hellman problem. The performance analysis shows that the proposed scheme is efficient.

A revocable storage CP-ABE scheme with constant ciphertext length in cloud storage.

The ciphertext policy attribute-based encryption (CP-ABE) is widely used in cloud storage. It not only provides a secure data sharing scheme but also has the characteristics of fine-grained access control. However, most CP-ABE schemes have problems such as the ciphertext length increases with the complexity of the access policy, the encryption scheme is complex, the computational efficiency is low, and the fine-grained revocation cannot be performed. In view of the above problems, this pa-per proposes an efficient CP-ABE scheme with fine-grained revocable storage and constant ciphertext length. The scheme combines proxy re-encryption with CP-ABE technology, adopts the flexible access strategy AND-gates on multi-valued attributes with wildcards (AND∗m ), and realizes revocable storage and fixed-length ciphertext. At the same time, in order to reduce the amount of user decryption calcu-lation, the complex operation in the decryption process is outsourced to the third-party server and the decryption result is verified to ensure the correctness of the information. Finally, the security of the scheme is proved under the decisional bilinear Diffie-Hellman (DBDH) assumption. In addition, the performance analysis shows that the scheme is efficient and feasible in cloud storage.

Group Key Agreement Protocol Based on Privacy Protection and Attribute Authentication

Group key agreement is a good way to ensure secure communication within a group. However, the identity authentication, privacy protection, and information sharing access control (different access rights may exist for different sensitivity of information) are key issues to be solved in group key agreement. Aiming at these problems, this paper proposes a group key agreement protocol based on privacy protection and attribute authentication (GKA-PPAA). The protocol proposes identity authentication for hidden attributes; it not only preserves the advantages of traditional identity-based key agreement protocol, but also provides hiding the identity information and privacy protection of the individual, and also proposes information sharing access control, which different secret information is shared among a set of members who have different levels of authority. It increases the flexibility of group key management. In addition, the group key factors are also calculated before the group key agreement, which eliminates most of the computation overhead due to the group key agreement. This protocol is proven secure under the discrete logarithm problem (DLP) and decisional bilinear Diffie-Hellman (DBDH) problem assumptions. The performance analysis shows that the proposed scheme is much more efficient than the existing ones.

Lattice-Based Key-Aggregate (Searchable) Encryption in Cloud Storage

In cloud storage, selectively sharing encrypted data is becoming increasingly important. One key design challenge is the management of encryption keys. Traditionally, a large quantity of encryption keys have to be managed by the data owner, and an equally large number of keyword trapdoors must be sent to the cloud for the purpose of searching over the shared data, which are cumbersome in terms of secure communication and management. Recently, key-aggregate (searchable) encryption schemes have been introduced to alleviate the problem. However, they were only designed under the Bilinear Diffie-Hellman Exponent assumption in the prior works. Lattice-based key-aggregate (searchable) encryption schemes are valuable, because they have security against quantum computing attacks, average-case to worse-case equivalence as well as simplicity and potential efficiency. Here we propose a key-aggregate encryption scheme and a key-aggregate searchable encryption scheme which are both based on a lattice problem (i.e., the Learning with Errors problem). Some key techniques are employed during the construction of the schemes. A basis delegation algorithm is designed to generate the aggregate key without increasing the lattice dimension. The encryption algorithms of the two schemes are trickily devised to make the encrypted files decryptable or searchable. To overcome the problem of general matrix multiplication failing to satisfy commutative law, a hash function is designed by using diagonalizable matrices to make the encrypted file decryptable and the trapdoor adjustable. We present the schemes' correctness proof, formal security analysis as well as performance analysis, which confirm that they are provably secure and practically efficient. To the best of our knowledge, the former is the first lattice-based key-aggregate encryption scheme and the latter is the first lattice-based key-aggregate searchable encryption scheme. We also demonstrate their application to cloud storage for searchable group data sharing by combining the two schemes.

Improved Cryptanalysis of Provable Certificateless Generalized Signcryption

Certificateless generalized signcryption adaptively work as certificateless signcryption, signature or encryption scheme having single algorithm for suitable storage-constrained environments. Recently, Zhou et al. proposed a novel Certificates generalized scheme, and proved its ciphertext indistinguishability under adaptive chosen ciphertext attacks (IND-CCA2) using Gap Bi-linear Diffie-Hellman and Computational Diffie-Hellman assumption as well as proved existential unforgeability against chosen message attacks (EUF-CMA) using the Gap Bi-linear Diffie-Hellman and Computational Diffie-Hellman assumption in random oracle model. In this paper, we analyzed Zhou et al. scheme and unfortunately proved IND-CCA2 insecure in encryption and signcryption modes in defined security model. We also present a practical and improved scheme, provable secure in random oracle model.

A New Encrypted Data Switching Protocol: Bridging IBE and ABE Without Loss of Data Confidentiality

Encryption technologies have become one of the most prevalent solutions to safeguard data confidentiality in many real-world applications, e.g., cloud-based data storage systems. Encryption outputting a relatively “static” format of encrypted data, however, may hinder further data operations. For example, encrypted data may need to be “transformed” into other formats for computation or other purposes. To enable encryption to be used in another device equipped with a different encryption mechanism, the concept of encryption switching was first proposed in CRYPTO 2016 for conversion particularly between Paillier and ElGamal encryptions. This paper considers the conversion between conventional identity-based and attribute-based encryptions and further proposes a concrete construction via the technique of proxy re-encryption. The construction is proved to be CPA secure in the standard model under q-decisional parallel bilinear Diffie-Hellman exponent assumption. The performance comparisons highlight that our bridging mechanism reduces computation and communication cost on the client side, especially when the data of the client is encrypted and outsourced to a remote cloud. The computational costs with respect to re-encryption (on the server side) and decryption (on the client side) are acceptable in practice.

Efficient Certificateless Public Key Cryptography With Equality Test for Internet of Vehicles

The fast progression of the Internet of Vehicles (IoV) has resulted in a large number of vehicles connecting to networks. This leads to massive growth in the data collected from vehicles via IoV. Fortunately, cloud computing provides a vast range of services such as operating systems, hardware, software, and resources. Therefore, the massive amount of data cumulated through IoV can be outsourced to the cloud. However, considering the untrusted nature of the cloud, the cumulated data must be encrypted before it is outsourced to the cloud server. Unfortunately, this ensures to difficulty while searching the data. To address this challenge, an efficient certificateless public key cryptography with equality test (CL-PKC-ET) is presented in this paper. In this scheme, the authorized cloud server has the permission to execute the equality test on encrypted data and retrieve the result without knowing any relevant information about the ciphertext. Our CL-PKC-ET scheme is demonstrated under the Bilinear Diffie-Hellman assumption in the random oracle model. Ultimately, we compare the CL-PKE-ET with a state-of-art scheme and the performance evaluation indicates that our scheme accomplishes 96.40%, 32.08%, and 43.98% reduction in computation costs during the encryption, decryption, and test stages, respectively. Therefore, we assert that our scheme is ideal for deployment in both the cloud and IoV environments.

How to Watermark Cryptographic Functions by Bilinear Maps

We introduce a notion of watermarking for cryptographic functions and propose a concrete scheme for watermarking cryptographic functions. Informally speaking, a digital watermarking scheme for cryptographic functions embeds information, called a mark, into functions such as one-way functions and decryption functions of public-key encryption. There are two basic requirements for watermarking schemes. A mark-embedded function must be functionally equivalent to the original function. It must be difficult for adversaries to remove the embedded mark without damaging the original functionality. In spite of its importance and usefulness, there have only been a few theoretical works on watermarking for functions (or programs). Furthermore, we do not have rigorous definitions of watermarking for cryptographic functions and concrete constructions. To solve the problem above, we introduce a notion of watermarking for cryptographic functions and define its security. Furthermore, we present a lossy trapdoor function (LTF) based on the decisional bilinear Diffie-Hellman problem problem and a watermarking scheme for the LTF. Our watermarking scheme is secure under the symmetric external Diffie-Hellman assumption in the standard model. We use techniques of dual system encryption and dual pairing vector spaces (DPVS) to construct our watermarking scheme. This is a new application of DPVS.

A hierarchical group key agreement protocol using orientable attributes for cloud computing

Group key agreement is one of the key technologies for ensuring information exchange security among group members. Due to different sensitivities of the information, group members may only want to exchange certain secret information under certain circumstances, and also due to different access permissions of member, certain information exchange may aim at different access authorities. Aiming at these requirements, a hierarchical group key agreement protocol using orientable attribute (HGKA-OA) is proposed in this paper. In this protocol, different secret information is shared among a set of members who have different authority levels. Assuming different permission levels correspond to different attributes or their combinations of the terminal, when one people has some secret information he can exchange information with some people who have the appropriate level of security permissions, rather than all the members in the group. The proposed scheme eliminates a majority of the computation task of terminals by moving identity authentication computation to the registration. In addition, the group key factors are also calculated before the group key agreement, which eliminates most of computation overhead due to group key agreement. This protocol is proven secure under the Decisional Bilinear Diffie-Hellman (DBDH) problem assumption and performance analysis shows that the proposed scheme is more efficient than existing works.

Identity-Based Proxy Signcryption Protocol with Universal Composability

Proxy signcryption means that the proxy signcrypter obtains the delegate authorization from the original signcrypter and then signcrypts the specified message on behalf of the original signcrypter. In this paper, we construct an identity-based proxy signcryption protocol (IBPSP) based on the universally composable (UC) framework. In the random oracle model, we prove that this protocol has the semantic security under the gap bilinear Diffie-Hellman and computational Diffie-Hellman assumptions. At the same time, an ideal functionality of the identity-based proxy signcryption protocol is defined in the UC security framework, and we also prove the equivalence between the universally composable identity-based proxy signcryption protocol and its IND-CCA2 and UF-CMA security. Analysis shows this IBPSP has both low computation complexity and semantic security together with UC security.

A searchable personal health records framework with fine-grained access control in cloud-fog computing.

Fog computing can extend cloud computing to the edge of the network so as to reduce latency and network congestion. However, existing encryption schemes were rarely used in fog environment, resulting in high computational and storage overhead. Aiming at the demands of local information for terminal device and the shortcomings of cloud computing framework in supporting mobile applications, by taking the hospital scene as an example, a searchable personal health records framework with fine-grained access control in cloud-fog computing is proposed. The proposed framework combines the attribute-based encryption (ABE) technology and search encryption (SE) technology to implement keyword search function and fine-grained access control ability. When keyword index and trapdoor match are successful, the cloud server provider only returns relevant search results to the user, thus achieving a more accurate search. At the same time, the scheme is multi-authority, and the key leakage problem is solved by dividing the user secret key distribution task. Moreover, in the proposed scheme, we securely outsource part of the encryption and decryption operations to the fog node. It is effective both in local resources and in resource-constrained mobile devices. Based on the decisional q-parallel bilinear Diffie-Hellman exponent (q-DBDHE) assumption and decisional bilinear Diffie-Hellman (DBDH) assumption, our scheme is proven to be secure. Simulation experiments show that our scheme is efficient in the cloud-fog environment.

Efficient Privacy-Preserving Access Control Scheme in Electronic Health Records System

The sharing of electronic health records (EHR) in cloud servers is an increasingly important development that can improve the efficiency of medical systems. However, there are several concerns focusing on the issues of security and privacy in EHR system. The EHR data contains the EHR owner’s sensitive personal information, if these data are obtained by a malicious user, it will not only cause the leakage of patient’s privacy, but also affect the doctor’s diagnosis. It is a very challenging problem for the EHR owner fully controls over own EHR data as well as preserves the privacy of himself. In this paper, we propose a new privacy-preserving access control (PPAC) scheme for EHR. To achieve fine-grained access control of the EHR data, we utilize the attribute-based signcryption (ABSC) mechanism to signcrypt data based on the access policy for the linear secret sharing schemes. Employing the cuckoo filter to hide the access policy, it could protect the EHR owner’s privacy information. In addition, the security analysis shows that the proposed scheme is provably secure under the decisional bilinear Diffie-Hellman exponent assumption and the computational Diffie-Hellman exponent assumption in the standard model. Furthermore, the performance analysis indicates that the proposed scheme achieves low costs of communication and computation compared with the related schemes, meanwhile preserves the EHR owner’s privacy. Therefore, the proposed scheme is better suited to EHR system.

Revocable hierarchical identity-based broadcast encryption

Hierarchical Identity-Based Broadcast Encryption (HIBBE) organizes users into a tree-like structure, and it allows users to delegate their decryption ability to subordinates and enable encryption to any subset of users while only intended users can decrypt. However, current HIBBE schemes do not support efficient revocation of private keys. Here, a new primitive called Revocable Hierarchical Identity-Based Broadcast Encryption (RHIBBE) is formalized that allows revocation of the HIBBE. Ciphertext indistinguishability is defined against the selectively Bounded Revocable Identity-Vector-Set and Chosen-Plaintext Attack (IND-sBRIVS-CPA). An IND-sBRIVS-CPA secure RHIBBE scheme is constructed with efficient revocation on prime-order bilinear groups. The unbounded version of the scheme is also shown to be secure but a little weaker than the former under the decisional n-Weak Bilinear Diffie-Hellman inversion assumption.

Identity-Based Encryption with Cloud Revocation Authority and Its Applications

Identity-based encryption (IBE) is a public key cryptosystem and eliminates the demands of public key infrastructure (PKI) and certificate administration in conventional public key settings. Due to the absence of PKI, the revocation problem is a critical issue in IBE settings. Several revocable IBE schemes have been proposed regarding this issue. Quite recently, by embedding an outsourcing computation technique into IBE, Li et al. proposed a revocable IBE scheme with a key-update cloud service provider (KU-CSP). However, their scheme has two shortcomings. One is that the computation and communication costs are higher than previous revocable IBE schemes. The other shortcoming is lack of scalability in the sense that the KU-CSP must keep a secret value for each user. In the article, we propose a new revocable IBE scheme with a cloud revocation authority (CRA) to solve the two shortcomings, namely, the performance is significantly improved and the CRA holds only a system secret for all the users. For security analysis, we demonstrate that the proposed scheme is semantically secure under the decisional bilinear Diffie-Hellman (DBDH) assumption. Finally, we extend the proposed revocable IBE scheme to present a CRA-aided authentication scheme with period-limited privileges for managing a large number of various cloud services.

Identity-Based Private Matching over Outsourced Encrypted Datasets

With wide use of cloud computing and storage services, sensitive information is increasingly centralized into the cloud to reduce the management costs, which raises concerns about data privacy. Encryption is a promising way to maintain the confidentiality of outsourced sensitive data, but it makes effective data utilization to be a very challenging task. In this paper, we focus on the problem of private matching over outsourced encrypted datasets in identity-based cryptosystem that can simplify the certificate management. To solve this problem, we propose an Identity-Based Private Matching scheme ( $\mathsf{IBPM}$ ), which realizes fine-grained authorization that enables the privileged cloud server to perform private matching operations without leaking any private data. We present the rigorous security proof under the Decisional Linear Assumption and Decisional Bilinear Diffie-Hellman Assumption. Furthermore, through the analysis of the asymptotic complexity and the experimental evaluation, we verify that the cost of our $\mathsf{IBPM}$ scheme is linear to the size of the dataset and it is more efficient than the existing work of Zheng and Xu [30] . Finally, we apply our $\mathsf{IBPM}$ scheme to build two efficient schemes, including identity-based fuzzy private matching as well as identity-based multi-keyword fuzzy search.