Multi-user Searchable Encryption Research Articles

Fast Multi-User Searchable Encryption with Forward and Backward Private Access Control

Untrusted servers are servers or storage entities lacking complete trust from the data owner or users. This characterization implies that the server hosting encrypted data may not enjoy full trust from data owners or users, stemming from apprehensions related to potential security breaches, unauthorized access, or other security risks. The security of searchable encryption has been put into question by several recent attacks. Currently, users can search for encrypted documents on untrusted cloud servers using searchable symmetric encryption (SSE). This study delves deeply into two pivotal concepts of privacy within dynamic searchable symmetric encryption (DSSE) schemes: forward privacy and backward privacy. The former serves as a safeguard against the linkage of recently added documents to previously conducted search queries, whereas the latter guarantees the irretrievability of deleted documents in subsequent search inquiries. However, the provision of fine-grained access control is complex in existing multi-user SSE schemes. SSE schemes may also incur high computation costs due to the need for fine-grained access control, and it is essential to support document updates and forward privacy. In response to these issues, this paper suggests a searchable encryption scheme that uses simple primitive tools. We present a multi-user SSE scheme that efficiently controls access to dynamically encrypted documents to resolve these issues, using an innovative approach that readily enhances previous findings. Rather than employing asymmetric encryption as in comparable systems, we harness low-complexity primitive encryption tools and inverted index-based DSSE to handle retrieving encrypted files, resulting in a notably faster system. Furthermore, we ensure heightened security by refreshing the encryption key after each search, meaning that users are unable to conduct subsequent searches with the same key and must obtain a fresh key from the data owner. An experimental evaluation shows that our scheme achieves forward and Type II backward privacy and has much faster search performance than other schemes. Our scheme can be considered secure, as proven in a random oracle model.

Privacy-Preserving Dynamic Multi-Keyword Ranked Search Scheme in Multi-User Settings

With the rapid development of consumer electronics in Industry 5.0, personalized service supplement based on the cloud infrastructure for the Internet of Things (IoT) has been a promising requirement pushed to consumers. During the massive and frequent IoT data interaction from the consumer-centric in Industry 5.0, efficiently searchable encryption for multiple consumers are indispensable. Existing multi-user searchable encryption is based on attribute and predicate encryption technology to realize one-to-many rather than realistic many-to-many scenarios. Moreover, multi-keyword ranked search, dynamic update, and search pattern hiding have not been implemented in the multi-user scenario. In this paper, to address the above problems for consumer electronics in Industry 5.0, we present a privacy-preserving dynamic multi-keyword ranked search scheme over encrypted cloud data to accomplish pay-as-you-consume cloud data security sharing. Our scheme designs a specific tree-based index structure and a “Greedy Breadth-First Search” algorithm to achieve the sub-linear search. To support dynamic updates in the cloud, a novel secure maximum generation protocol is proposed. Finally, the security analysis and experiment evaluation prove our scheme cannot only preserve the privacy of index and search patterns but also support dynamic update operations under the multi-writer/multi-reader setting at an acceptable cost.

One for all: Efficient verifiable dynamic multi-user searchable encryption in the presence of corrupted users

Dynamic multi-user searchable symmetric encryption (DMUSSE) enables the data owner to dynamically outsource encrypted database to the cloud server and selectively share the search capability with data users. However, inter-user state synchronization is expensive but often necessary in multi-user setting. In addition, only a few works are proposed against the malicious servers that achieve verifiability (guarantee the integrity of query results) by deploying a Merkle tree for all database entries in a straightforward way, which is inevitably subject to logarithmic communication overhead. In this work, we propose a new verifiable DMUSSE scheme with improved performance, while maintaining user-server collusion resistance. Concretely, we first design an efficient and forward-and-backward-secure DMUSSE scheme with the aid of Hyperledger Fabric (a permissioned blockchain), greatly reducing synchronous communication and computation. In particular, our scheme does not reveal any information about uncorrupted users when corrupted users collude with an adversarial server. Then, we achieve efficient verifiability of query results based on multiset hash functions with O(1) communication cost. Finally, we compare our scheme with the state-of-the-art solutions O-μSE and Q-μSE (Chamani et al. TDSC 2021). Experimental results show that our scheme brings at least 90.9% communication savings, 2.75×, 109.2×, and 11.67× speedup in search, update, and verify time, respectively.

Multi-User Collusion-Resistant Searchable Encryption for Cloud Storage

The continued development of cloud computing requires technologies protecting users' data privacy even from the cloud providers themselves, such as Multi-user searchable encryption. It allows data owners to selectively enable users to perform keyword searches over their encrypted data stored at a cloud server. For privacy purposes, it is important to limit what an adversarial server can infer about the encrypted data, even if it colludes with some users. Clearly, in this case it can learn the content of data shared with these “corrupted” users, however, it is important to ensure this collusion does not reveal information about parts of the dataset that are only shared with “uncorrupted” users via <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">cross-user</i> leakage. In this work, we propose three novel multi-user searchable encryption schemes eliminating cross-user leakage. Compared to previous ones, our first two schemes are the first to achieve asymptotically <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">optimal search time</i> . Our third scheme achieves minimal user storage and forward privacy with respect to data sharing, but slightly slower search performance. We formally prove the security of our schemes under reasonable assumptions. Moreover, we implement them for textual documents and tabular databases and evaluate their computation and communication performance with encouraging results.

MULTI-OWNER DATA SHARING

In the case of Provable Multiple files Data that changes over time in cloud computing,possession refers to the dynamic transfer of stored data to a cloud server. Multiple files indicate that the data will be replicated on multiple servers. The project owner uploads the data to the cloud server using automatic data capture, and the files are then stored on multiple servers. Data loss due to hacking and server crashes can be avoided by uploading data to multiple servers. By distributing the secret key among the several users, multi-user searchable encryption directly adapts a single-user system to a multi-user environment. This is obviously not capable of achieving user accountability, and in the event of user revocation, it necessitates key renewal among non-revoked users, which then necessitates re-encrypting the external database. These issues might be resolved if the cloud implemented access control before responding to user search requests, but as noted in, access control deployment is prohibitively expensive in practise. To make matters worse, users must maintain a separate set of secrets for authentication and authorization. We introduced a new technique, fully homomorphic encryption (FHE), in this project for multiple data file acquisition, file security, and data corruption. For data protection, we must use the FHE algorithm in this project. There are three of them: keygen, copygen, and taggen.The process described above was carried out in the existing system. Keywords- Multiple file data; Cloud server; Fully homomorphic encryption ; FHE algorithm;

DuMSE: Toward Practical and Dynamic Multiuser Search Over Encrypted Cloud Data Against Keyword Guessing Attack

For multiuser search scenarios over encrypted cloud data, the multiuser searchable encryption (MUSE) technology is a viable solution for incorporating privacy protection and favorable operability functions together. However, current MUSE technologies suffer from three practical limitations: 1) a secure channel between data owner and users will greatly increase the burden of owner; 2) a trusted third party (TTP) is required in some solutions; and 3) some solutions cannot resist keyword guessing attack (KGA), which means that the information of search trapdoor is easily leaked. In order to solve the above three problems, our first practical solution (DuMSE) without secure channel and without TTP is proposed in this article, which also can resist KGA. With inverted indexes, the search time complexity of DuMSE can be reduced to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$r$ </tex-math></inline-formula> , where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$r$ </tex-math></inline-formula> is the number of corresponding data. To support dynamically updating data, our second dynamic solution based on DuMSE is also proposed in this article, named as dynamic DuMSE (dDuMSE). The construction of dDuMSE includes not only the above features of DuMSE but also a new feature. Our analysis and experimental results show that the proposed schemes are secure and practical.

A Hierarchical Searchable Encryption Scheme Using Blockchain-Based Indexing

Focusing on the fine-grained access control challenge of multi-user searchable encryption, we propose a hierarchical searchable encryption scheme using blockchain-based indexing (HSE-BI). First, we propose a hierarchical search index structure based on a DAG-type access policy and a stepwise hierarchical key derivation mechanism; which we outsourced to the blockchain network to achieve reliable hierarchical search. We design a dynamic append-only update protocol for the blockchain-based index to deal with adding and deleting files. Secondly, we propose a hierarchical authorization mechanism based on broadcast encryption to achieve fine-grained search permission granting and revoking, which can prevent a malicious server from colluding with corrupted users. The security and complexity analysis shows that HSE-BI achieves optimal search time while satisfying adaptive secure and revocation secure. Our experimental results are encouraging, e.g., compared with the traditional multi-user searchable encryption schemes, HSE-BI’s hierarchical search policy does not impact the search performance visually. The growth rate of the search latency decreases with the increasing number of hierarchical users, which can act as an efficient crypto tool to open up venues for other applications. We demonstrate that HSE-BI is more suitable for actual applications with fine-grained access requirements and can act as an efficient crypto tool to open up venues for other applications.

Parallel Key-Insulated Multiuser Searchable Encryption for Industrial Internet of Things

With the rapid development of the industrial Internet of Things (IIoT) and cloud computing, an increasing number of companies outsource their data to cloud servers to save costs. To protect data privacy, sensitive industrial data must be encrypted before being outsourced to cloud servers. A multiuser searchable encryption (MUSE) scheme was introduced to ensure high efficiency of encrypted data retrieval. In an IIoT system with numerous users, the existing MUSE schemes suffer from certain key exposure problems owing to the limited key protection of smart devices and frequent queries by users. In this article, we propose a parallel key-insulated MUSE scheme for IIoT. This scheme utilizes broadcast encryption technology to implement MUSE. In addition, our scheme introduces a key-insulated primitive to improve the tolerance to key exposure. The security of our scheme is proved in the random oracle model. The experimental results show that our scheme achieves high computational efficiency.

Encrypted Speech Retrieval Scheme Based on Multiuser Searchable Encryption in Cloud Storage

In order to solve the problem of multiuser security sharing and privacy protection of the speech data in cloud storage and realize efficient encrypted speech retrieval, an encrypted speech retrieval scheme based on multiuser searchable encryption was proposed. Firstly, the ciphertext-policy attribute-based encryption (CP-ABE) and searchable encryption (SE) are combined to support a multiuser searchable speech encryption scheme, which achieves the encryption and fine-grained access control of the speech data. Secondly, the Mel frequency cepstral coefficient (MFCC) feature of the original speech that is used as the input of the long- and short-term memory network (LSTM) is extracted to perform the deep semantic feature extraction as the speech keywords. Finally, the speech keywords are encrypted to generate a secure index, bound together with the encrypted speech, and then stored in the cloud. During the user retrieving, the keywords of query speech are extracted by utilizing the trained LSTM to generate the search trapdoor of the user and then uploaded to the cloud server, and the Euclidean distance is used for matching the security index with the search trapdoor. In addition, a proxy server is introduced to execute the partial ciphertext decryption operations to reduce computation overhead and storage space. The theoretical analysis and experimental results show that the proposed scheme has higher security and retrieval accuracy and can realize the secure storage of the massive speech data and multiuser data sharing.

Towards Multi-user Searchable Encryption Scheme with Support for SQL Queries

Towards Multi-user Searchable Encryption Scheme with Support for SQL Queries

Edge-Cloud-Assisted Multiuser Forward Secure Searchable Encryption (EMFSSE) Scheme in the P2P Networking Environment

P2P network enables users to share resources effectively. However, with the advent of the big data era, the sensitive data of users in P2P network are also increasing dramatically. In order to solve the contradiction between the huge amount of sensitive data and the limited local storage space, an increasing number of users choose to encrypt their sensitive data and store them in the cloud server. For the problem of the secure storage and flexible access of large amounts of user data in P2P networks, an edge-cloud-assisted multiuser forward secure searchable encryption scheme is proposed. The scheme uses the proxy reencryption technique to optimize the multiuser searchable encryption and prevent the decryption key from being directly transmitted between users. By introducing an edge-cloud architecture, the system achieves efficient communication and timely response capabilities. The security analysis proves that our scheme achieves the CPA (chosen-plaintext attack) security based on DBDH assumption and the forward privacy. Finally, the theoretical and experimental comparisons between this scheme and other schemes show that our scheme has high efficiency in the process of data update, search, and trapdoor generation. In addition, due to the use of edge-cloud architecture, our scheme reduces about 90% and 75% of the user’s consumption in the encryption and token generation process.

Server-aided searchable encryption in multi-user setting

Searchable encryption schemes allow users to search encrypted data containing some keyword without decrypting the data. It protects the data privacy of data owners, meanwhile facilitates efficient data access in secure cloud storage service. Most of the existing schemes only considered the single-user setting, in which a user uploads his encrypted data and later performs searches on it. However, the majority of databases in practice do not only serve one user; instead, they support write operations by multiple data owners and search operations by some authorized users. There exists the following issues in existing multi-user searchable encryption schemes. First, some schemes allow only one data owner to write to the encrypted database; second, a number of schemes may require the data owner to interact with the authorized users to distribute secret keys; third, some other schemes cannot efficiently support the search authorization revocation on users, and do not achieve the trapdoor unlinkability. In this paper, we address these issues by proposing a server-aided searchable encryption scheme in multi-user setting. In our scheme, the data owners only need to know the public key of an administration server to generate the searchable ciphertext, regardless of the number of authorized users. Furthermore, our scheme is shown to be semantically secure against outside keyword guessing attacks. Finally, the performance analyses and comparisons with some existing schemes demonstrate that our scheme achieves better performance.

Multi-user searchable encryption voice in home IoT system

With the development of home IoT voice systems that can provide interfaces, such as Amazon Alex, it is easy to disclose personal privacy when people search voice conveniently. It becomes a challenge how to search voice effectively with privacy-preserving for multi-user. In the paper, we propose a multi-user searchable encrypted voice scheme (MUSEV). The outline is as the follows. voices are divided into two parts. One is answer. The other is query, or key words of voices. Answer part will be encrypted and query part will be converted into features. The feature and encrypted answer are bound together and uploaded to the server. If the feature is matched successfully, the answer part encrypted can be acquired. First, the feature of voice query is extracted using Mel Frequency Cepstral Coefficents (MFCC). Next, the feature of voice query and voice answer encrypted by Advanced Encryption Standard (AES) are bound. Before uploading the server, we adopt obfuscation function to hide the features on the server. The features obfuscated will be matched. If the query feature is matched successfully, the encrypted voice answer associated with it will be returned to a user. Then, the user can get the plaintext of voice answer by decrypting these voice answers encrypted. To improve multi-user retrieval performance, we employ Long Short-Term Memory networks (LSTM) for voice conversion between users. Meantime, Diffie-Hellman algorithm is used to exchange parameters between users to enhance security. Theoretical analysis and experimental results prove that MUSEV is secure and effective.

A Secure and Efficient Task Matching Scheme for Spatial Crowdsourcing

The sharing economy has greatly promoted the rapid development and application of spatial crowdsourcing. Although privacy-preserving spatial task matching as an indispensable part has been extensively explored, existing schemes cannot be deployed into the practical environment due to drawbacks in the one-side location protection, the matching efficiency, and the dynamic updates. In this study, we propose a novel Secure and Efficient Spatial Task Matching framework (SESTM) with utilizing multi-user searchable encryption and secure index technique, which enables to preserve the location privacy of requesters and workers while achieving efficient task allocation and good user scalability. Specifically, requesters firstly transform and encrypt their task locations before being outsourced, and we secondly design a secure and dynamic tree-based index SD-Tree for SC-server to merge these uploaded encrypted data without knowing their underlying content. Finally, SESTM provides efficient task matching services for multiple workers based on encrypted queries. Furthermore, SD-Tree also provides fast delete and insert operations under logarithmic time to reduce the dynamic update overhead for real SC services. Extensive theoretical analysis and performance evaluation demonstrate the practicality of our method.

Towards Multi-user Searchable Encryption Supporting Boolean Query and Fast Decryption

Towards Multi-user Searchable Encryption Supporting Boolean Query and Fast Decryption

Keyword guessing on multi-user searchable encryption

Keyword guessing on multi-user searchable encryption

Dual-side privacy-preserving task matching for spatial crowdsourcing

With the popularity of mobile phones and the ubiquity of wireless transmission technologies, spatial crowdsourcing (SC) has emerged as a novel approach to outsource location-based tasks to a set of workers who physically move to the designated locations to perform the tasks. To achieve the accurate task matching, both requesters and workers need to expose their locations or queries to the SC-Server, which raises security concerns. Although many protection measures have been proposed, there are some drawbacks in one-side protection, dual-server setting and user scalability when they are applied to the practical crowdsourcing environment. In this paper, we design a general framework for spatial task matching in a single-server setting to simultaneously protect the privacy for both tasks and workers. Combining multi-user searchable encryption with segment tree, we propose two different schemes to achieve the spatial task matching over the encrypted data. Efficient user enrollment and revocation are also supported. Extensive experiments validate the feasibility of our schemes.

Efficient Attribute-Based Searchable Encryption on Cloud Storage

Cloud service is very popular for its computing and storage capacity at lower cost. More and more data are being moved to the cloud to reduce storage cost. On the other hand, since the cloud is not fully trustable, in order to protect data privacy against third-parties and even the cloud server, they are usually encrypted by cryptology technology before uploading. However, many operations, such as searching, are hard to perform on encrypted data. To solve this problem, searchable encryption has emerged. Searchable encryption in multi-user setting is much less efficient than in single-user setting. In order to address this problem, we propose a multi-owner to multi-user searchable encryption scheme based on attribute-based encryption. Our scheme keeps data secure in the cloud even against the cloud server. It allows users with appropriate authorizations to perform search operations on encrypted data. In addition, search tokens are generated by users instead of data owners. We prove that token privacy and index privacy are well protected in our scheme. The cloud server and illegimate users are not able to get any useful information about search tokens and ciphertexts. Ciphertexts of our scheme are constant-size, which reduce the time-complexity and bandwidth overhead of our scheme.

Fine-grained search and access control in multi-user searchable encryption without shared keys

Searchable encryption schemes enable secure sharing and efficient retrieval of encrypted documents stored in the cloud. Multi-user symmetric searchable encryption allows multiple users to upload encrypted data to the cloud and selectively authorize other people to search and retrieve documents without revealing any information about either the search query or sensitive information. This however, poses major challenges since it involves managing the access control policies of a set of users by a third party. Selectively sharing files among an arbitrary set of users is more challenging than allowing all members of a group to access a set of documents. The proposed scheme ensures that the search returns only those documents that are accessible to the querier and guarantees that only authorized users are allowed to decrypt a document. A bilinear map accumulator combined with pairing based cryptography ensures that only authorized users can decrypt a shared document. Prior schemes have addressed the problem using shared keys or by using trusted third parties. The proposed scheme supports both keyword searches and selective sharing of data among multiple users in the cloud without requiring shared keys or trusted third parties. The security of our scheme is proved using rigorous security analysis.

Secure and efficient encrypted keyword search for multi-user setting in cloud computing

A key challenge to design searchable encryption in multi-user setting lies in the efficient management of encryption and search keys. Existing multi-user searchable encryption schemes either extend the single-user searchable encryption framework with broadcast encryption or require search user refers to the data owner and get the search token. However, this implies the necessity that the data owner distributes a single shared secret key among the group of users or requires the data owner stay online to authorize other users to search. In this paper, we address this practical problem, which is neglected in the literature. We also study secret-key-recovery attack where a malicious user can deduce a valid secret when given a search token. We show such attack violates secret key privacy, which is important in the whole system. Inspired by asymmetric group key agreement and multilinear map technology, we provide a secure and efficient encrypted keyword search scheme for multi-user setting, in which a data owner can share data with a group users without knowing which user in the group. In the proposed scheme, (a) each user has his own secret key, (b) each user generates trapdoors without getting any help from data owner or the third party, (c) our scheme features constant communication overhead, and (d) our scheme resist the secret-key-recovery attack. Our scheme preserves the traceability inherited from the asymmetric group key agreement system. We offer rigorous security proof of our scheme, and the performance analysis demonstrates the efficiency of our scheme.