Attribute-based encryption (ABE) is suitable for mobile cloud storage to protect data confidentiality and realize fine-grained data access control. It is essential for ABE schemes to achieve attribute revocation as users’ attributes may be changed frequently. Keyword search over encrypted data also needs to be solved in the mobile cloud storage. In addition, computational efficiency is a consideration for the resource-constrained mobile device. Focusing on the above-mentioned problems, an efficiently revocable and searchable ABE (RSABE) scheme for the mobile cloud storage is proposed. In our scheme, the function of attribute revocation is efficiently achieved by delegating the update of secret key and ciphertext to the powerful cloud server. Keyword search is also supported, in which data owners and users can generate the keywords index and search trapdoor, respectively, without relying on always online trusted authority. Furthermore, an outsourced decryption technology is used to reduce the computational load of decryption on user side. Our RSABE scheme is proven to be semantically secure against selective ciphertext policy and chosen plaintext attack, and to be secure against chosen keyword attack in the random oracle model. Finally, performance evaluation demonstrates that our scheme is highly efficient.

Efficiently Revocable and Searchable Attribute-Based Encryption Scheme for Mobile Cloud Storage

Searchable encryption is a promising technique that allows cloud service provider return the interested files to the user, even if the shared files are encrypted. However, once encrypted data is uploaded to the cloud, the data owner loses the physical control of the data; the cloud service provider may face the problem of duplicate data occupying the storage space; how can the data user obtain the legal access rights? Therefore, data integrity detection, data deduplication and reasonable access authorization become the focus of attention. To address these problems, we propose a novel verifiable attribute-based keyword search over encrypted data supporting data deduplication. In the scheme, attribute-based encryption is introduced to achieve effective access authorization based on its one-to-many advantage, as well data confidentiality. A data label of each shared file is generated to finish data deduplication, while the third-party auditor and hash function are adopted to ensure data integrity, including ciphertext, plaintext and symmetric key. Moreover, in order to solve the problem of high computational load caused by attribute-based encryption, outsourcing decryption is used to optimize the scheme. The formal security analysis shows that our scheme can implement fine-grained authorization to search and realize indistinguishable keywords, unforgeability of signatures and confidentiality of ciphertexts. Meanwhile, the results of the experiment reveal that our scheme has a low band-width communication, storage and computability.

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Verifiable Attribute-Based Keyword Search Over Encrypted Cloud Data Supporting Data Deduplication

With the emergence of cloud computing, data owners are showing interest to outsource the data to the cloud servers and allowing the data users to access the data as and when required.
However, outsourcing sensitive data into the cloud leads to privacy issues. Encrypting the data before outsourcing provides privacy, but it does not provide search functionality. To achieve search over encrypted data without compromising the privacy, searchable encryption (SE) schemes have been proposed. It protects the user’s sensitive information by providing searchability on encrypted data stored in the cloud. In this paper, we surveyed different SE schemes which are existed in the cloud domain. In this survey, we presented the taxonomy of the SE schemes: symmetric searchable encryption, public key searchable encryption, and attribute-based searchable encryption schemes, and then provided a detailed discussion on the SE schemes in terms of index structure and search functionality. A comparative analysis of SE schemes is also provided on security and performance. Furthermore, we discussed the challenges, future directions, and applications of SE schemes.

A scoping review of searchable encryption schemes in cloud computing: taxonomy, methods, and recent developments

Outsourcing data in cloud storage is gaining popularity recently. For protecting data privacy, the data should be encrypted, and it is thus critical to provide search services for encrypted outsourced data. However, it becomes a problem about how to retrieve encrypted data while protecting data privacy at the same time. Therefore, public key encryption with keyword search (PEKS) is proposed. Nevertheless, the majority of the existing PEKS schemes are based on bilinear mappings and do not provide quantum security. Although some lattice-based PEKS schemes have been proposed, they cannot support conjunctive keyword search. In this paper, we first propose a public key encryption with conjunctive keyword search (PECK) using lattices. Our PECK scheme provides efficient search over encrypted data containing multiple keywords for a single data user. To support multiple data users, a multi-user PECK scheme is also presented. The two schemes are proved secure against indistinguishable chosen keyword attacks (IND-CKA) based on learning with errors (LWE) problem in the random oracle model. Finally, we provide performance evaluation of our proposed scheme by theoretical analysis and experimental simulation.

Public key encryption with conjunctive keyword search on lattice

Keyword search over encrypted cloud data based on blockchain in smart medical applications

Conjunctive searchable encryption is an efficient way to perform multi-keyword search over encrypted data in cloud storage. However, most existing methods do not take into account the integrity verification of the search result. Moreover, existing integrity verification methods can only verify the integrity of single-keyword search results, which cannot meet the requirements of conjunctive search. To address this problem, we proposed a conjunctive keyword searchable encryption scheme with an authentication mechanism that can efficiently verify the integrity of search results. The proposed scheme is based on the dynamic searchable symmetric encryption and adopts the Merkle tree and bilinear map accumulator to prove the correctness of set operations. It supports conjunctive keyword as input for conjunctive search and gives the server the ability to prove the integrity of the search result to the user. Formal proofs and extensive experiments show that the proposed scheme is efficient, unforgeable and adaptive secure against chosen-keyword attacks.

Yuhai Qin

Papers

Integrity-verifiable conjunctive keyword searchable encryption in cloud storage