Abstract Public key encryption with equality test (PKEET) plays an important role in the cloud storage. It allows a third party to test whether two ciphertexts contain the same message without decryption. Since the third party is not fully trusted, it is sometimes necessary to prevent the third party from testing the ciphertexts all the time. To this end, we propose the notion of revocable public key encryption with equality test (R-PKEET). We give the construction of R-PKEET in the random oracle model, which employs time key to update trapdoor and partial ciphertexts. In details, our scheme enables a user to revoke the third party’s test right by sending a time key to the cloud server, which is responsible for updating partial ciphertexts using the time key. Compared with related works, our scheme achieves both lightweight revocation and lower computational complexity by using Shamir’s secret sharing and Lagrange interpolating polynomial.

Abstract The encryption of user data is crucial when employing electronic health record services to guarantee the security of the data stored on cloud servers. Attribute-based encryption (ABE) scheme is considered a powerful encryption technique that offers flexible and fine-grained access control capabilities. Further, the multi-user collaborative access ABE scheme additionally supports users to acquire access authorization through collaborative works. However, the existing multi-user collaborative access ABE schemes do not consider the different weights of collaboration users. Therefore, using these schemes for weighted multi-user collaborative access results in redundant attributes, which inevitably reduces the efficiency of the ABE scheme. This paper proposes a revocable and verifiable weighted attribute-based encryption with collaborative access scheme (RVWABE-CA), which can provide efficient weighted multi-user collaborative access, user revocation, and data integrity verification, as the fundamental cornerstone for establishing a robust framework to facilitate secure sharing of electronic health records in a public cloud environment. In detail, this scheme employs a novel weighted access tree to eliminate redundant attributes, utilizes encryption version information to control user revocation, and establishes Merkle Hash Tree for data integrity verification. We prove that our scheme is resistant against chosen plaintext attack. The experimental results demonstrate that our scheme has significant computational efficiency advantages compared to related works, without increasing storage or communication overhead. Therefore, the RVWABE-CA scheme can provide an efficient and flexible weighted collaborative access control and user revocation mechanism as well as data integrity verification for electronic health record systems.

More and more images/videos will be consumed by both human and machine in many fields. Optimization of image processing algorithm for hybrid human and machine becomes a challenging task. To address this problem, feature structure similarity index (FSSIM) is proposed in this paper as an objective metric for image quality assessment (IQA), by defining structure similarity in low-level feature domain. Features extracted by the first convolutional layer of pre-trained resnet50 network are treated as common feature domain for both human and machine vision. Moreover, multi-scale structure similarity with weighting matrix is used as distance measure in the feature domain. FSSIM is capable of fully decoupling image processing and its downstream machine tasks, enabling image processing algorithm optimization for hybrid human and machine vision. Experimental results show FSSIM-optimized image processing algorithms achieve significant performance improvement over existing metrics in context of machine vision tasks including object detection and semantic segmentation. Meanwhile reconstructed images of FSSIM-optimized algorithms are better friendly to human vision.

With the increasing electricity consumption and the wide application of renewable energy sources, energy auction attracts a lot of attention due to its economic benefits. In recent years, much research employs double auction mechanisms to design a market model for smart grid and shows its paramount importance for energy trading. However, few of them are able to quickly and securely identify the potential winner or winners from all sealed bids and asks throughout the auction process. In this paper, we propose an efficient multi-user threshold equality retrieval (MTER) by a novel non-interactive threshold public key encryption with equality test (T-PKEET) as a building block for bid-ask filtering to help different double auction mechanisms be implemented effectively in the smart grid. In this new T-PKEET primitive, the key used to authorize the equality test is shared amongnservers so that at leastkservers are collaborated to compute the test function: a combiner who has a userU’s ciphertextCand another user Û’s ciphertext Ĉ wishes to carry out the equality test on ciphertextsCand Ĉ Preferably, T-PKEET solves a challenge problem of resisting against message recovery attack in PKEET system. We construct a concrete T-PKEET scheme with flexible authorization by issuing tag-based test key shares and ciphertext-based test key shares and prove it to achieve st-IND-CCA2 security against insider adversary in the standard model. The experimental results show that the Trapdoor and Test algorithms of T-PKEET scheme have significant efficiency, whose cost is only 8.46% and 17.78% that of the work closest to ours. Therefore, our construction can effectively facilitate demand responses of the filtering on sealed bids and asks for double auction in smart grid.

Cloud-based Internet of Things (IoT) system is becoming a promising architecture in our modern society. However, cloud-based IoT system brings a number of challenges in the security aspect while improving the efficiency of data analytics. Especially, searching on encrypted data is challenging given today’s technology. Thus searchable encryption has emerged as one of the important research fields. Public key encryption with equality test (PKEET) provides a simple but useful mechanism to cryptographically protect data while keeping it available for equality test on ciphertexts. However, PKEET schemes in the literature are not suitable for cloud-based IoT system with privacy protection enhancement since the untrustworthy cloud server may be interested in query results by itself and hence reveal the private information of data owner out of the expectation of data user. Even worse, it could launch offline message recovery attack (OMRA) based on the returned query results. In this paper, we introduce a new notion of public key encryption with outsourced equality test (PKE-OET) for adapting to cloud-based IoT environments as well as providing a flexible solution to resist against OMRA without taking any information about entrusted parties as input in encryption. We formally define the security model of PKE-OET against three types of adversary including IND-CCA-I, IND-CCA-II and IND-CCA-III. We present a generic PKE-OET construction using a new variant of smooth projective hash function (SPHF) with a novel Lin-Hom property, which is of independent interest. Then we provide an efficient PKE-OET instantiation from Symmetric eXternal Diffie-Helllman (SXDH) assumption and show its practicality for cloud-based IoT environments through a series of experiments on Cloud Server and Raspberry Pi.

Abstract ID-based encryption with equality test (IBEET) allows a tester to compare ciphertexts encrypted under different public keys for checking whether they contain the same message. In this paper, we first introduce group mechanism into IBEET and propose a new primitive, namely group ID-based encryption with equality test (G-IBEET). With the group mechanism: (1) group administrator can authorize a tester to make comparison between ciphertexts of group users, but it cannot compare their ciphertexts with any ciphertext of any user who is not in the group. Such group granularity authorization can make IBEET that adapts to group scenario; (2) for the group granularity authorization, only one trapdoor, named group trapdoor, should be issued to the tester, which can greatly reduce the cost of computation, transmission and storage of trapdoors in traditional IBEET schemes; (3) G-IBEET can resist the insider attack launched by the authorized tester, which is an open problem in IBEET. We give definitions for G-IBEET and propose a concrete construction with an efficient test algorithm. We then give its security analysis in the random oracle model.

Abstract Group signature (GS) allows each member in a group to do signatures anonymously on behalf of the group under management of a group authority. Membership revocation has been a central issue in GS and widely studied so far. The mechanism of verifier local revocation for GS, first formalized by Boneh and Shacham, has an advantage of making the signers free from fetching the up-to-date information of the revoked users and practicality in the scenario of periodically update in the large population of group users. Most of work related to group signature with verifier-local revocation either can only achieve selfless anonymity or have inefficient constructions due to complicate primitives. Aiming to a recent chosen ciphertext attack-almost-full anonymous notion for GS, this paper presents an efficient GS with verifier local revocation in the standard model by adding a new primitive plaintext searchable encryption into Groth’s GS under Canard et al.’s framework. We prove that it has backward unlinkability to ensure that all signatures generated by the user before the revocation remain anonymous, even if it is revoked later.

Thanks to its convenience and cost-savings feature, cloud computing ushers a new era. Yet its security and privacy issues must not be neglected. Private set intersection (PSI) is useful and important in many cloud computing applications, such as document similarity, genetic paternity and data mining. The cloud server performs intersection operations on two outsourced encrypted datasets of data owners. In the existing protocols, however, data owners cannot decide whether to use all or part of their encrypted data to compute the intersection, nor can they specify whom to compare with. In this paper, we introduce an enhanced notion of outsourced PSI, called authorized PSI (APSI), which supports flexible authorization and cross-type authorized comparison of datasets. To demonstrate this notion, we propose a concrete APSI protocol, and prove it to be secure in the random oracle model based on simple number-theoretic assumptions. Experimental results show that our APSI protocol has performance comparable with existing related outsourced PSI protocols.

Abstract In the era of cloud computing, public key encryption with keyword search (PEKS) is an extremely useful cryptographic tool for searching on encryption data, whose strongest security notion is indistinguishability encryption against chosen ciphertext attack (ind-cca). Adballa et al. presented a transformation from identity based encryption (IBE) to PEKS in the Theory of Cryptography Conference 2010. This paper proposes a new framework of ind-cca secure PEKS in the standard model. Our main technical tool is a newly introduced notion of smooth projective hash function with key mapping, in which the hash key hk is mapped into another mapping projection key mhp besides the classical projection key hp. Finally, we provide an instantiation of our framework based on symmetric eXternal Diffie–Hellman assumption.

In the identity-based broadcast encryption (IBBE), only these users whose identities are chosen in the ciphertext computing can decrypt the encrypted message. In this paper, we introduce an extension of IBBE, namely Identity-Based Broadcast Encryption for Inner Product (IBBE-IP), where message encryption is replaced by inner product encryption (IPE) introduced by Abdalla et al. (PKC 2015). Precisely, in the IBBE-IP, the private key is associated with a pair of an identity and a vector (ID,y→)⁠. The user with private key of (ID,y→) can decrypt the encrypted vector x→ for an identity set S selected by the encryptor and learn the inner product 〈x→,y→〉 if and only if ID∈S⁠. Differing from the IBBE, the decryption in the IBBE-IP yields the inner product associated with the encrypted vector without leaking any information of the vector. The encrypted vector is protected as long as the number of selected identities is less than their length. We present a construction of IBBE-IP with constant-size private keys and it supports unbounded private key queries, which was unachieved in the previous works of IPE in the public-key setting. The security of our proposed scheme is proved in the random oracle model.

We present dRMT (disaggregated Reconfigurable Match-Action Table), a new architecture for programmable switches. dRMT overcomes two important restrictions of RMT, the predominant pipeline-based architecture for programmable switches: (1) table memory is local to an RMT pipeline stage, implying that memory not used by one stage cannot be reclaimed by another, and (2) RMT is hardwired to always sequentially execute matches followed by actions as packets traverse pipeline stages. We show that these restrictions make it difficult to execute programs efficiently on RMT.

The Database-As-a-Service (DaaS) model provides seamless mechanisms for database management and service. As a countermeasure to security treats, encryption technologies have been widely adopted in database systems. Accordingly, privacy-preserving queries on encrypted databases has become an important research topic. In this paper, we present the first solution of authorized equi-join for multiple data contributors in the PKC-based setting. With the improved ciphertext security under checkability, our underlying cryptographic construction could be used independently as a standard procedure for many other relational operations, for instance, intersection, difference, and set union. As a feature, our scheme allows flexible authorization policies for the join operation by the controlled trapdoor transitivity, which has not yet been studied thoroughly in the literature. Our proposed scheme is efficient in encryption and execution and has a reasonable ciphertext size. It can be applied as a building block for data query in the DaaS model.

Unlicensed LTE system holds high potential to effectively offload data/video traffic from the crowded licensed band. Previous effort of deploying LTE in the unlicensed band (e.g. license-assisted access LAA) relies on one or more LTE carriers in the licensed band, and may not be desired in certain scenarios. This paper studies a new technology of utilizing LTE directly in an unlicensed band, without any assistance from a licensed band, i.e. the stand-alone unlicensed LTE, for which we term SAiL. Various SAiL design considerations are discussed and several technologies are proposed to enable a success SAiL.

Probabilistic public key encryption with equality test (PKEET), introduced by Yang et al. in CT-RSA 2010, is able to check whether two ciphertexts are encryptions of the same message under different public keys without leaking anything else about the message encrypted under either public key. PKEET schemes have many applications, for example, in constructing searchable encryption and partitioning encrypted data. Previous PKEET schemes lack a delegation mechanism for users to specify who can perform the equality test between their ciphertexts. In this paper, we propose the notion of public key encryption with delegated equality test (PKE-DET), which requires only the delegated party to deal with the work in a practical multi-user setting, and present a concrete construction in Type 2 pairing, which is provably secure under the newly introduced security notions.

We reformalize and recast the notion of public key encryption with equality test (PKEET), which was proposed in CT-RSA 2010 and supports to check whether two ciphertexts encrypted under different public keys contain the same message. PKEET has many interesting applications, for example, in constructing searchable encryption and partitioning encrypted data. However, the original PKEET scheme lacks an authorization mechanism for a user to control the comparison of its ciphertexts with others’. In this paper, we study the authorization mechanism for PKEET, and propose four types of authorization policies to enhance the privacy of users’ data. We give the definitions of the policies, propose a PKEET scheme supporting these four types of authorization at the same time, and prove its security based on the computational Diffie–Hellman assumption in the random oracle model. To the best of our knowledge, it is the only PKEET scheme supporting flexible authorization.

ABSTRACT In outsourced database, it is desirable to store sensitive data in an encrypted form to reduce security and privacy risks because the server may not be fully trusted. Several approaches have been proposed in recent literatures to efficiently support queries on encrypted databases. Most researches focus on keywords search and range query while few works study on join query because of a lack of related cryptography primitives. We propose a solution of a privacy‐preserving general join supporting both equality tests and simple non‐equality tests on ciphertexts by using the revised Boneh–Goh–Nissim encryption algorithm and a Bloom filter. Finally, we analyze its advantages and disadvantages by the comparison with existing method on the performance and the newly introduced security notions. Copyright © 2013 John Wiley & Sons, Ltd.

Individuals who have upper limb movement problems include people with cerebral palsy (CP) and stroke victims. Both these conditions lead to difficulties in daily activities such as reaching, grasping etc. Virtual reality (VR), which could provide a repetitive multimodal task-oriented rehabilitation environment for patients to undertake self-training in safety, is considered to be a suitable tool for medical health rehabilitation. Using electromyography (EMG) biofeedback in rehabilitation could provide patients with opportunities to improve the ability by assessing their muscle activity response and learning self-control of movement during specific training tasks. This paper presents a study on developing EMG as an important interactive tool in a VR based system for hand rotation and grasping motion rehabilitation. The input interface includes an EMG system and a real-time magnetic motion tracking system, and the output interface is a PC monitor. The developed EMG biofeedback based VR system enables the user to interact with virtual objects in real-time with multiform feedback. Ten healthy subjects participated in the preliminary task evaluation test, and the results suggest that the specified skills have improved during training. The beneficial effects of the developed system indicate the potential values for further clinical application.

Real-world surface textures normally comprise rough surface geometry and various reflectance properties. These surface textures are different from 2D still texture as their images can therefore vary dramatically with illumination directions. Research into hole filling has long been focusing on 2D images, surfaces of 3D models or video clips to reconstruct missing information around the hole area. However, no reports are available regarding hole filling for rough or 3D surface textures. This paper presents a simple framework for filling holes on 3D surface texture. Firstly, we represent 3D surface texture under varied illumination directions using gradient and albedo maps as well as eigen base images. Then, the hole area is searched and an order map is established for filling the hole iteratively using patches from surface representation. Finally, the filling algorithm for the 3D surface representation is performed according to the order map to generate missing information in the hole area. Experiments show that the proposed approach can not only produce hole-filled images under arbitrary illumination directions, but also has the ability to repair the surface geometry.