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2019-10-02
Span, M. T., Mailloux, L. O., Grimaila, M. R., Young, W. B..  2018.  A Systems Security Approach for Requirements Analysis of Complex Cyber-Physical Systems. 2018 International Conference on Cyber Security and Protection of Digital Services (Cyber Security). :1–8.
Today's highly interconnected and technology reliant environment places greater emphasis on the need for dependably secure systems. This work addresses this problem by detailing a systems security analysis approach for understanding and eliciting security requirements for complex cyber-physical systems. First, a readily understandable description of key architectural analysis definitions and desirable characteristics is provided along with a survey of commonly used security architecture analysis approaches. Next, a tailored version of the System-Theoretic Process Analysis approach for Security (STPA-Sec) is detailed in three phases which supports the development of functional-level security requirements, architectural-level engineering considerations, and design-level security criteria. In particular, these three phases are aligned with the systems and software engineering processes defined in the security processes of NIST SP 800-160. Lastly, this work is important for advancing the science of systems security by providing a viable systems security analysis approach for eliciting, defining, and analyzing traceable security, safety, and resiliency requirements which support evaluation criteria that can be designed-for, built-to, and verified with confidence.
2019-09-30
Liu, Y., Li, L., Gao, Q., Cao, J., Wang, R., Sun, Z..  2019.  Analytical Model of Torque-Prediction for a Novel Hybrid Rotor Permanent Magnet Machines. IEEE Access. 7:109528–109538.

This paper presents an analytical method for predicting the electromagnetic performance in permanent magnet (PM) machine with the spoke-type rotor (STR) and a proposed hybrid rotor structure (HRS), respectively. The key of this method is to combine magnetic field analysis model (MFAM) with the magnetic equivalent circuit model. The influence of the irregular PM shape is considered by the segmentation calculation. To obtain the boundary condition in the MFAM, respectively, two equivalent methods on the rotor side are proposed. In the STR, the average flux density of the rotor core outer-surface is calculated to solve the Laplace's equation with considering for the rotor core outer-surface eccentric. In the HRS, based on the Thevenin's theorem, the equivalent parameters of PM remanence BreB and thickness hpme are obtained as a given condition, which can be utilized to compute the air-gap flux density by conventional classic magnetic field analysis model of surface-mounted PMs with air-gap region. Finally, the proposed analytical models are verified by the finite element analysis (FEA) with comparisons of the air-gap flux density, flux linkage, back-EMF and electromagnetic torque, respectively. Furthermore, the performance that the machine with the proposed hybrid structure rotor can improve the torque density as explained.

Onufer, J., Ziman, J., Duranka, P., Kravčák, J..  2019.  The Study of Closure Domain Structure Dynamics in Bistable Microwires Using the Technique of Three-Level Field Pulses. IEEE Transactions on Magnetics. 55:1–6.

The process of release of a single domain wall from the closure domain structure at the microwire ends and the process of nucleation of the reversed domain in regions far from the microwire ends were studied using the technique that consists in determining the critical parameters of the rectangular magnetic field pulse (magnitude-Hpc and length-τc) needed for free domain wall production. Since these processes can be influenced by the magnitude of the magnetic field before or after the application of the field pulse (Hi, τ), we propose a modified experiment in which the so-called three-level pulse is used. The three-level pulse starts from the first level, then continues with the second measuring rectangular pulse (Hi, τ), which ends at the third field level. Based on the results obtained in experiments using three-level field pulses, it has been shown that reversed domains are not present in the remanent state in regions far from the microwire ends. Some modification of the theoretical model of a single domain wall trapped in a potential well will be needed for an adequate description of the depinning processes.

Elbidweihy, H., Arrott, A. S., Provenzano, V..  2018.  Modeling the Role of the Buildup of Magnetic Charges in Low Anisotropy Polycrystalline Materials. IEEE Transactions on Magnetics. 54:1–5.

A Stoner-Wohlfarth-type model is used to demonstrate the effect of the buildup of magnetic charges near the grain boundaries of low anisotropy polycrystalline materials, revealed by measuring the magnetization during positive-field warming after negative-field cooling. The remnant magnetization after negative-field cooling has two different contributions. The temperature-dependent component is modeled as an assembly of particles with thermal relaxation. The temperature-independent component is modeled as an assembly of particles overcoming variable phenomenological energy barriers corresponding to the change in susceptibility when the anisotropy constant changes its sign. The model is applicable to soft-magnetic materials where the buildup of the magnetic charges near the grain boundaries creates demagnetizing fields opposing, and comparable in magnitude to, the anisotropy field. The results of the model are in qualitative agreement with published data revealing the magneto-thermal characteristics of polycrystalline gadolinium.

Xu, F., Peng, R., Zheng, T., Xu, X..  2019.  Development and Validation of Numerical Magnetic Force and Torque Model for Magnetically Levitated Actuator. IEEE Transactions on Magnetics. 55:1–9.

To decouple the multi-axis motion in the 6 degrees of freedom magnetically levitated actuators (MLAs), this paper introduces a numerical method to model the force and torque distribution. Taking advantage of the Gaussian quadrature, the concept of coil node is developed to simplify the Lorentz integral into the summation of the interaction between each magnetic node in the remanence region and each coil node in the coil region. Utilizing the coordinate transformation in the numerical method, the computation burden is independent of the position and the rotation angle of the moving part. Finally, the experimental results prove that the force and torque predicted by the numerical model are rigidly consistent with the measurement, and the force and torque in all directions are decoupled properly based on the numerical solution. Compared with the harmonic model, the numerical wrench model is more suitable for the MLAs undertaking both the translational and rotational displacements.

Hohlfeld, J., Czoschke, P., Asselin, P., Benakli, M..  2019.  Improving Our Understanding of Measured Jitter (in HAMR). IEEE Transactions on Magnetics. 55:1–11.

The understanding of measured jitter is improved in three ways. First, it is shown that the measured jitter is not only governed by written-in jitter and the reader resolution along the cross-track direction but by remanence noise in the vicinity of transitions and the down-track reader resolution as well. Second, a novel data analysis scheme is introduced that allows for an unambiguous separation of these two contributions. Third, based on data analyses involving the first two learnings and micro-magnetic simulations, we identify and explain the root causes for variations of jitter with write current (WC) (write field), WC overshoot amplitude (write-field rise time), and linear disk velocity measured for heat-assisted magnetic recording.

Kim, Seung-Wook, Park, Sun Young, Han, Junghyun.  2018.  Magnetization Dynamics for Magnetic Object Interactions. ACM Trans. Graph.. 37:121:1–121:13.
The goal of this paper is to simulate the interactions between magnetic objects in a physically correct way. The simulation scheme is based on magnetization dynamics, which describes the temporal change of magnetic moments. For magnetization dynamics, the Landau-Lifshitz-Gilbert equation is adopted, which is widely used in micromagnetics. Through effectively-designed novel models of magnets, it is extended into the macro scale so as to be combined with real-time rigid-body dynamics. The overall simulation is stable and enables us to implement mutual induction and remanence that have not been tackled by the state-of-the-art technique in magnet simulation. The proposed method can be applied to various fields including magnet experiments in the virtual world.
Bickel, J. E., Aidala, K. E..  2019.  Phase Diagram of 360° Domain Walls in Magnetic Rings. IEEE Transactions on Magnetics. 55:1–6.

One method to increase bit density in magnetic memory devices is to use multi-state structures, such as a ferromagnetic nanoring with multiple domain walls (DWs), to encode information. However, there is a competition between decreasing the ring size in order to more densely pack bits and increasing it to make multiple DWs stable. This paper examines the effects of ring geometry, specifically inner and outer diameters (ODs), on the formation of 360° DWs. By sequentially increasing the strength of an applied circular magnetic field, we examine how DWs form under the applied field and whether they remain when the field is returned to zero. We examine the relationships between field strength, number of walls initially formed, and the stability of these walls at zero field for different ring geometries. We demonstrate that there is a lower limit of 200 nm to the ring diameter for the formation of any 360° DWs under an applied field, and that a high number of 360° DWs are stable at remanence only for narrow rings with large ODs.

Davila, Y. G., Júnior, F. A. Revoredo, Peña-Garcia, R., Padrón-Hernández, E..  2019.  Peak in Angular Dependence of Coercivity in a Hexagonal Array of Permalloy Spherical Nanocaps. IEEE Magnetics Letters. 10:1–3.

Micromagnetic simulations of coercivity as a function of external magnetic field direction were performed for a hexagonal array of hemispherical Permalloy nanocaps. The analysis was based on hysteresis loops for arrangements of nanocaps of variable thickness (5 nm and 10 nm). The angular dependence of coercivity had a maximum at about 80° with respect to the arrangement plane. An increase in coercivity with nanocap thickness is related to the magnetization reversal mechanism, where the dipole energy of individual caps generates an effective intermediate axis, locking the magnetic moments. The coercivity has maximum values of 109 Oe for 5 nm and 156 Oe for 10 nm thickness. The remanence decreases monotonically with angle. This is associated with the influence of shape anisotropy, where the demagnetizing field in the plane of the array is much smaller than the demagnetizing field perpendicular to the plane.

Liu, B., He, L., Zhang, H., Sfarra, S., Fernandes, H., Perilli, S., Ren, J..  2019.  Research on stress detection technology of long-distance pipeline applying non-magnetic saturation. IET Science, Measurement Technology. 13:168–174.

In order to study the stress detection method on long-distance oil and gas pipeline, the distribution characteristics of the surface remanence signals in the stress concentration regions must be known. They were studied by using the magnetic domain model in the non-magnetic saturation state. The finite element method was used herein with the aim to analyse the static and mechanical characteristics of a ferromagnetic specimen. The variation law of remanence signal in stress concentration regions was simulated. The results show that a residue signal in the stress concentration region exists. In addition, a one-to-one correspondence in the non-magnetic saturation environment is evident. In the case of magnetic saturation, the remanence signal of the stress concentration region is covered and the signal cannot be recognised.

Jiao, Y., Hohlfield, J., Victora, R. H..  2018.  Understanding Transition and Remanence Noise in HAMR. IEEE Transactions on Magnetics. 54:1–5.

Transition noise and remanence noise are the two most important types of media noise in heat-assisted magnetic recording. We examine two methods (spatial splitting and principal components analysis) to distinguish them: both techniques show similar trends with respect to applied field and grain pitch (GP). It was also found that PW50can be affected by GP and reader design, but is almost independent of write field and bit length (larger than 50 nm). Interestingly, our simulation shows a linear relationship between jitter and PW50NSRrem, which agrees qualitatively with experimental results.

2019-09-26
Liu, Y., Zhang, J., Gao, Q..  2018.  A Blockchain-Based Secure Cloud Files Sharing Scheme with Fine-Grained Access Control. 2018 International Conference on Networking and Network Applications (NaNA). :277-283.
As cloud services greatly facilitate file sharing online, there's been a growing awareness of the security challenges brought by outsourcing data to a third party. Traditionally, the centralized management of cloud service provider brings about safety issues because the third party is only semi-trusted by clients. Besides, it causes trouble for sharing online data conveniently. In this paper, the blockchain technology is utilized for decentralized safety administration and provide more user-friendly service. Apart from that, Ciphertext-Policy Attribute Based Encryption is introduced as an effective tool to realize fine-grained data access control of the stored files. Meanwhile, the security analysis proves the confidentiality and integrity of the data stored in the cloud server. Finally, we evaluate the performance of computation overhead of our system.
Mishra, B., Jena, D..  2018.  CCA Secure Proxy Re-Encryption Scheme for Secure Sharing of Files through Cloud Storage. 2018 Fifth International Conference on Emerging Applications of Information Technology (EAIT). :1-6.
Cloud Storage Service(CSS) provides unbounded, robust file storage capability and facilitates for pay-per-use and collaborative work to end users. But due to security issues like lack of confidentiality, malicious insiders, it has not gained wide spread acceptance to store sensitive information. Researchers have proposed proxy re-encryption schemes for secure data sharing through cloud. Due to advancement of computing technologies and advent of quantum computing algorithms, security of existing schemes can be compromised within seconds. Hence there is a need for designing security schemes which can be quantum computing resistant. In this paper, a secure file sharing scheme through cloud storage using proxy re-encryption technique has been proposed. The proposed scheme is proven to be chosen ciphertext secure(CCA) under hardness of ring-LWE, Search problem using random oracle model. The proposed scheme outperforms the existing CCA secure schemes in-terms of re-encryption time and decryption time for encrypted files which results in an efficient file sharing scheme through cloud storage.
Pant, S., Kumar, V..  2018.  BitTrusty: A BitCoin Incentivized Peer-to-Peer File Sharing System. 2018 IEEE 3rd International Conference on Computing, Communication and Security (ICCCS). :148-155.
Among the various challenges faced by the P2P file sharing systems like BitTorrent, the most common attack on the basic foundation of such systems is: Free-riding. Generally, free-riders are the users in the file sharing network who avoid contributing any resources but tend to consume the resources unethically from the P2P network whereas white-washers are more specific category of free-riders that voluntarily leave the system in a frequent fashion and appearing again and again with different identities to escape from the penal actions imposed by the network. BitTorrent being a collaborative distributed platform requires techniques for discouraging and punishing such user behavior. In this paper, we propose that ``Instead of punishing, we may focus more on rewarding the honest peers''. This approach could be presented as an alternative to other mechanisms of rewarding the peers like tit-for-tat [10], reciprocity based etc., built for the BitTorrent platform. The prime objective of BitTrusty is: providing incentives to the cooperative peers by rewarding in terms of cryptocoins based on blockchain. We have anticipated three ways of achieving the above defined objective. We are further investigating on how to integrate these two technologies of distributed systems viz. P2P file sharing systems and blockchain, and with this new paradigm, interesting research areas can be further developed, both in the field of P2P cryptocurrency networks and also when these networks are combined with other distributed scenarios.
Nelmiawati, Arifandi, W..  2018.  A Seamless Secret Sharing Scheme Implementation for Securing Data in Public Cloud Storage Service. 2018 International Conference on Applied Engineering (ICAE). :1-5.
Public cloud data storage services were considered as a potential alternative to store low-cost digital data in the short term. They are offered by different providers on the Internet. Some providers offer limited free plans for the users who are starting the service. However, data security concern arises when data stored are considered as a valuable asset. This study explores the usage of secret sharing scheme: Rabin's IDA and Shamir's SSA to implement a tool called dCloud for file protection stored in public cloud storage in a seamless way. It addresses data security by hiding its complexities when targeting ordinary non-technical users. The secret key is automatically generated by dCloud in a secure random way on Rabin's IDA. Shamir's SSA completes the process through dispersing the key into each of Rabin's IDA output files. Moreover, the Hash value of the original file is added to each of those output files to confirm the integrity of the file during reconstruction. Besides, the authentication key is used to communicate with all of the defined service providers during storage and reconstruction as well. It is stored into local secure key-store. By having a key to access the key-store, an ordinary non-technical user will be able to use dCloud to store and retrieve targeted file within defined public cloud storage services securely.
Torkura, K. A., Sukmana, M. I. H., Meinig, M., Cheng, F., Meinel, C., Graupner, H..  2018.  A Threat Modeling Approach for Cloud Storage Brokerage and File Sharing Systems. NOMS 2018 - 2018 IEEE/IFIP Network Operations and Management Symposium. :1-5.
Cloud storage brokerage systems abstract cloud storage complexities by mediating technical and business relationships between cloud stakeholders, while providing value-added services. This however raises security challenges pertaining to the integration of disparate components with sometimes conflicting security policies and architectural complexities. Assessing the security risks of these challenges is therefore important for Cloud Storage Brokers (CSBs). In this paper, we present a threat modeling schema to analyze and identify threats and risks in cloud brokerage brokerage systems. Our threat modeling schema works by generating attack trees, attack graphs, and data flow diagrams that represent the interconnections between identified security risks. Our proof-of-concept implementation employs the Common Configuration Scoring System (CCSS) to support the threat modeling schema, since current schemes lack sufficient security metrics which are imperatives for comprehensive risk assessments. We demonstrate the efficiency of our proposal by devising CCSS base scores for two attacks commonly launched against cloud storage systems: Cloud sStorage Enumeration Attack and Cloud Storage Exploitation Attack. These metrics are then combined with CVSS based metrics to assign probabilities in an Attack Tree. Thus, we show the possibility combining CVSS and CCSS for comprehensive threat modeling, and also show that our schemas can be used to improve cloud security.
Wang, Fei, Kwon, Yonghwi, Ma, Shiqing, Zhang, Xiangyu, Xu, Dongyan.  2018.  Lprov: Practical Library-Aware Provenance Tracing. Proceedings of the 34th Annual Computer Security Applications Conference. :605-617.
With the continuing evolution of sophisticated APT attacks, provenance tracking is becoming an important technique for efficient attack investigation in enterprise networks. Most of existing provenance techniques are operating on system event auditing that discloses dependence relationships by scrutinizing syscall traces. Unfortunately, such auditing-based provenance is not able to track the causality of another important dimension in provenance, the shared libraries. Different from other data-only system entities like files and sockets, dynamic libraries are linked at runtime and may get executed, which poses new challenges in provenance tracking. For example, library provenance cannot be tracked by syscalls and mapping; whether a library function is called and how it is called within an execution context is invisible at syscall level; linking a library does not promise their execution at runtime. Addressing these challenges is critical to tracking sophisticated attacks leveraging libraries. In this paper, to facilitate fine-grained investigation inside the execution of library binaries, we develop Lprov, a novel provenance tracking system which combines library tracing and syscall tracing. Upon a syscall, Lprov identifies the library calls together with the stack which induces it so that the library execution provenance can be accurately revealed. Our evaluation shows that Lprov can precisely identify attack provenance involving libraries, including malicious library attack and library vulnerability exploitation, while syscall-based provenance tools fail to identify. It only incurs 7.0% (in geometric mean) runtime overhead and consumes 3 times less storage space of a state-of-the-art provenance tool.
Khan, Mohammad Taha, Hyun, Maria, Kanich, Chris, Ur, Blase.  2018.  Forgotten But Not Gone: Identifying the Need for Longitudinal Data Management in Cloud Storage. Proceedings of the 2018 CHI Conference on Human Factors in Computing Systems. :543:1-543:12.
Users have accumulated years of personal data in cloud storage, creating potential privacy and security risks. This agglomeration includes files retained or shared with others simply out of momentum, rather than intention. We presented 100 online-survey participants with a stratified sample of 10 files currently stored in their own Dropbox or Google Drive accounts. We asked about the origin of each file, whether the participant remembered that file was stored there, and, when applicable, about that file's sharing status. We also recorded participants' preferences moving forward for keeping, deleting, or encrypting those files, as well as adjusting sharing settings. Participants had forgotten that half of the files they saw were in the cloud. Overall, 83% of participants wanted to delete at least one file they saw, while 13% wanted to unshare at least one file. Our combined results suggest directions for retrospective cloud data management.
Dziembowski, Stefan, Eckey, Lisa, Faust, Sebastian.  2018.  FairSwap: How To Fairly Exchange Digital Goods. Proceedings of the 2018 ACM SIGSAC Conference on Computer and Communications Security. :967-984.
We introduce FairSwap – an efficient protocol for fair exchange of digital goods using smart contracts. A fair exchange protocol allows a sender S to sell a digital commodity x for a fixed price p to a receiver R. The protocol is said to be secure if R only pays if he receives the correct x. Our solution guarantees fairness by relying on smart contracts executed over decentralized cryptocurrencies, where the contract takes the role of an external judge that completes the exchange in case of disagreement. While in the past there have been several proposals for building fair exchange protocols over cryptocurrencies, our solution has two distinctive features that makes it particular attractive when users deal with large commodities. These advantages are: (1) minimizing the cost for running the smart contract on the blockchain, and (2) avoiding expensive cryptographic tools such as zero-knowledge proofs. In addition to our new protocols, we provide formal security definitions for smart contract based fair exchange, and prove security of our construction. Finally, we illustrate several applications of our basic protocol and evaluate practicality of our approach via a prototype implementation for fairly selling large files over the cryptocurrency Ethereum. This article is summarized in: the morning paper an interesting/influential/important paper from the world of CS every weekday morning, as selected by Adrian Colyer
Ghareh Chamani, Javad, Papadopoulos, Dimitrios, Papamanthou, Charalampos, Jalili, Rasool.  2018.  New Constructions for Forward and Backward Private Symmetric Searchable Encryption. Proceedings of the 2018 ACM SIGSAC Conference on Computer and Communications Security. :1038-1055.
We study the problem of dynamic symmetric searchable encryption. In that setting, it is crucial to minimize the information revealed to the server as a result of update operations (insertions and deletions). Two relevant privacy properties have been defined in that context: forward and backward privacy. The first makes it hard for the server to link an update operation with previous queries and has been extensively studied in the literature. The second limits what the server can learn about entries that were deleted from the database, from queries that happen after the deletion. Backward privacy was formally studied only recently (Bost et al., CCS 2017) in a work that introduced a formal definition with three variable types of leakage (Type-I to Type-III ordered from most to least secure), as well as the only existing schemes that satisfy this property. In this work, we introduce three novel constructions that improve previous results in multiple ways. The first scheme achieves Type-II backward privacy and our experimental evaluation shows it has 145-253X faster search computation times than previous constructions with the same leakage. Surprisingly, it is faster even than schemes with Type-III leakage which makes it the most efficient implementation of a forward and backward private scheme so far. The second one has search time that is asymptotically within a polylogarithmic multiplicative factor of the theoretical optimal (i.e., the result size of a search), and it achieves the strongest level of backward privacy (Type-I). All previous Type-I constructions require time that is at least linear in the total number of updates for the requested keywords, even the (arbitrarily many) previously deleted ones. Our final scheme improves upon the second one by reducing the number of roundtrips for a search at the cost of extra leakage (Type-III).
Blömer, Johannes, Löken, Nils.  2018.  Cloud Architectures for Searchable Encryption. Proceedings of the 13th International Conference on Availability, Reliability and Security. :25:1-25:10.
Blömer et al. have presented a cloud architecture for enabling fine-grained cryptographic access control to data in the cloud. The architecture is intended to provide this service to large-scale orgnaizations. We revisit the cloud architecture, and enrich it with searchable encryption. In the process, we identify some shortcomings of Blömer et al.'s architecture, that prevent many cryptographic primitives from being implemented within the framework of the architecture. Subsequently, we propose fixes to these issues. As a result, we are able to propose a concrete instantiation of searchable encryption, in the form of Bost's $Σ$o$\phi$o$ς$ scheme, in Blömer et al.'s architecture. Moreover, with our fixes, other primitives can be adapted to the architecture as well.
Kodera, Y., Kuribayashi, M., Kusaka, T., Nogami, Y..  2018.  Advanced Searchable Encryption: Keyword Search for Matrix-Type Storage. 2018 Sixth International Symposium on Computing and Networking Workshops (CANDARW). :292-297.
The recent development of IoT technologies and cloud storages, many types of information including private information have been gradually outsourced. For such a situation, new convenient functionalities such as arithmetic and keyword search on ciphertexts are required to allow users to retrieve information without leaking any information. Especially, searchable encryptions have been paid much attention to realize a keyword search on an encrypted domain. In addition, an architecture of searchable symmetric encryption (SSE) is a suitable and efficient solution for data outsourcing. In this paper, we focus on an SSE scheme which employs a secure index for searching a keyword with optimal search time. In the conventional studies, it has been widely considered that the scheme searches whether a queried keyword is contained in encrypted documents. On the other hand, we additionally take into account the location of a queried keyword in documents by targeting a matrix-type data format. It enables a manager to search personal information listed per line or column in CSV-like format data.
Xu, J., Ying, C., Tan, S., Sun, Z., Wang, P., Sun, Z..  2018.  An Attribute-Based Searchable Encryption Scheme Supporting Trapdoor Updating. 2018 IEEE 16th Intl Conf on Dependable, Autonomic and Secure Computing, 16th Intl Conf on Pervasive Intelligence and Computing, 4th Intl Conf on Big Data Intelligence and Computing and Cyber Science and Technology Congress(DASC/PiCom/DataCom/CyberSciTech). :7-14.
In the cloud computing environment, a growing number of users share their own data files through cloud storage. However, there will be some security and privacy problems due to the reason that the cloud is not completely trusted, so it needs to be resolved by access control. Attribute-based encryption (ABE) and searchable encryption (SE) can solve fine-grained access control. At present, researchers combine the two to propose an attribute-based searchable encryption scheme and achieved remarkable results. Nevertheless, most of existing attribute-based searchable encryption schemes cannot resist online/offline keyword guessing attack. To solve the problem, we present an attribute-based (CP-ABE) searchable encryption scheme that supports trapdoor updating (CSES-TU). In this scheme, the data owner can formulate an access strategy for the encrypted data. Only the attributes of the data user are matched with the strategy can the effective trapdoor be generated and the ciphertext be searched, and that this scheme will update trapdoors at the same time. Even if the keywords are the same, new trapdoors will be generated every time when the keyword is searched, thus minimizing the damage caused by online/offline keyword guessing attack. Finally, the performance of the scheme is analyzed, and the proof of correctness and security are given at the same time.
Li, S., Wang, F., Shi, T., Kuang, J..  2019.  Probably Secure Multi-User Multi-Keyword Searchable Encryption Scheme in Cloud Storage. 2019 IEEE 3rd Information Technology, Networking, Electronic and Automation Control Conference (ITNEC). :1368-1372.
Searchable encryption server protects privacal data of data owner from leaks. This paper analyzes the security of a multi-user searchable encryption scheme and points out that this scheme does not satisfy the invisibility of trapdoors. In order to improve the security of the original scheme, this paper proposes a probably secure multi-user multi-keyword searchable encryption scheme. New secheme not only ensures the confidentiality of the cipher text keyword, but also does not increase the encryption workload of the data owner when the new data user joins. In the random oracle model, based on the hard problem of decisional Diffie-Hellman, it is proved that the scheme has trapdoor indistinguishability. In the end, obtained by the simulation program to achieve a new computationally efficient communication at low cost.