• Journal of Information Processing Systems
• /
• v.14 no.5
• /
• pp.1087-1101
• /
• 2018

As cloud computing has become a widespread technology, malicious attackers can obtain the private information of users that has leaked from the service provider in the outsourced databases. To resolve the problem, it is necessary to encrypt the database prior to outsourcing it to the service provider. However, the most existing data encryption schemes cannot process a query without decrypting the encrypted databases. Moreover, because the amount of the data is large, it takes too much time to decrypt all the data. For this, Programmable Order-Preserving Secure Index Scheme (POPIS) was proposed to hide the original data while performing query processing without decryption. However, POPIS is weak to both order matching attacks and data count attacks. To overcome the limitations, we propose a group order-preserving data encryption scheme (GOPES) that can support efficient query processing over the encrypted data. Since GOPES can preserve the order of each data group by generating the signatures of the encrypted data, it can provide a high degree of data privacy protection. Finally, it is shown that GOPES is better than the existing POPIS, with respect to both order matching attacks and data count attacks.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.11
• /
• pp.5560-5579
• /
• 2019

Searchable symmetric encryption (SSE) scheme can perform search on encrypted data directly without revealing the plain data and keywords. At present, many constructive SSE schemes were proposed. However, they cannot really resist the malicious adversary, because it (i.e., the cloud server) may delete some important data. As a result, it is very likely that the returned search results are incorrect. In order to better guarantee the integrity of outsourcing data, and ensure the correction of returned search results at the same time, in this paper, we combine SSE with blockchain (BC), and propose a SSE-on-BC framework model. We then construct two concrete schemes based on the size of the data, which can better provide privacy protection and integrity verification for data. Lastly, we present their security and performance analyses, which show that they are secure and feasible.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.12 no.7
• /
• pp.3375-3400
• /
• 2018

With the advent of database-as-a-service (DAAS) and cloud computing, more and more data owners are motivated to outsource their data to cloud database in consideration of convenience and cost. However, it has become a challenging work to provide security to database as service model in cloud computing, because adversaries may try to gain access to sensitive data, and curious or malicious administrators may capture and leak data. In order to realize privacy preservation, sensitive data should be encrypted before outsourcing. In this paper, we present a secure and practical system over encrypted cloud data, called QSDB (queryable and secure database), which simultaneously supports SQL query operations. The proposed system can store and process the floating point numbers without compromising the security of data. To balance tradeoff between data privacy protection and query processing efficiency, QSDB utilizes three different encryption models to encrypt data. Our strategy is to process as much queries as possible at the cloud server. Encryption of queries and decryption of encrypted queries results are performed at client. Experiments on the real-world data sets were conducted to demonstrate the efficiency and practicality of the proposed system.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.2
• /
• pp.1043-1063
• /
• 2019

With delegating proxy to process data before outsourcing, data owners in restricted access could enjoy flexible and powerful cloud storage service for productivity, but still confront with data integrity breach. Identity-based data auditing as a critical technology, could address this security concern efficiently and eliminate complicated owners' public key certificates management issue. Recently, Yu et al. proposed an Identity-Based Public Auditing for Dynamic Outsourced Data with Proxy Processing (https://doi.org/10.3837/tiis.2017.10.019). It aims to offer identity-based, privacy-preserving and batch auditing for multiple owners' data on different clouds, while allowing proxy processing. In this article, we first demonstrate this scheme is insecure in the sense that malicious cloud could pass integrity auditing without original data. Additionally, clouds and owners are able to recover proxy's private key and thus impersonate it to forge tags for any data. Secondly, we propose an improved scheme with provable security in the random oracle model, to achieve desirable secure identity based privacy-preserving batch public auditing with proxy processing. Thirdly, based on theoretical analysis and performance simulation, our scheme shows better efficiency over existing identity-based auditing scheme with proxy processing on single owner and single cloud effort, which will benefit secure big data storage if extrapolating in real application.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.27 no.4
• /
• pp.971-980
• /
• 2017

Data deduplication can be utilized to reduce storage space in cloud storage services by storing only a single copy of data rather than all duplicated copies. Users who are concerned the confidentiality of their outsourced data can use secure encryption algorithms, but it makes data deduplication ineffective. In order to reconcile data deduplication with encryption, Liu et al. proposed a new server-side cross-user deduplication scheme by exploiting password authenticated key exchange (PAKE) protocol in 2015. In this paper, we demonstrate that this scheme has side channel which causes insecurity against the confirmation-of-file (CoF), or duplicate identification attack.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.10 no.10
• /
• pp.5171-5189
• /
• 2016

With the popularity of cloud computing, many data owners outsource their graph data to the cloud for cost savings. The cloud server is not fully trusted and always wants to learn the owners' contents. To protect the information hiding, the graph data have to be encrypted before outsourcing to the cloud. The adjacent vertex search is a very common operation, many other operations can be built based on the adjacent vertex search. A boolean adjacent vertex search is an important basic operation, a query user can get the boolean search results. Due to the graph data being encrypted on the cloud server, a boolean adjacent vertex search is a quite difficult task. In this paper, we propose a solution to perform the boolean adjacent vertex search over encrypted graph data in cloud computing (BASG), which maintains the query tokens and search results privacy. We use the Gram-Schmidt algorithm and achieve the boolean expression search in our paper. We formally analyze the security of our scheme, and the query user can handily get the boolean search results by this scheme. The experiment results with a real graph data set demonstrate the efficiency of our scheme.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.14 no.2
• /
• pp.133-141
• /
• 2018

The purpose of this study was to propose a model of knowledge transfer in IT outsourcing. In this study, structural holes were chosen as antecedent factors, and job performance as a consequence factor. We conducted a survey in which we collected data from 42 respondents working in one of the leading IT companies in Seoul, South Korea. The data were analyzed using UCINET 6 and SmartPLS 2.0. The antecedent factors (structural holes in closeness network and in professional network) turned out to be statistically significant. Knowledge transfer considerably influenced job performance. Lastly, implications and limitations of these findings were discussed, and directions for future research were suggested.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.17 no.2
• /
• pp.450-470
• /
• 2023

Traditional cloud computing faces some challenges such as huge energy consumption, network delay and single point of failure. Edge computing is a typical distributed processing platform which includes multiple edge servers closer to the users, thus is more robust and can provide real-time computing services. Although outsourcing data to edge servers can bring great convenience, it also brings serious security threats. In order to provide image retrieval while ensuring users' data privacy, a privacy preserving image retrieval scheme in edge environment is proposed. Considering the distributed characteristics of edge computing environment and the requirement for lightweight computing, we present a privacy-preserving image retrieval scheme in edge computing environment, which two or more "honest but curious" servers retrieve the image quickly and accurately without divulging the image content. Compared with other traditional schemes, the scheme consumes less computing resources and has higher computing efficiency, which is more suitable for resource-constrained edge computing environment. Experimental results show the algorithm has high security, retrieval accuracy and efficiency.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2021.05a
• /
• pp.263-264
• /
• 2021

The purpose of this study is to empirically confirm the effect of the characteristics of construction workers on the occurrence of defects in construction. In this study, the degree of direct construction is measured through the ratio of the direct recruitment and outsourcing manpower of the original contractor, and the effect of this on the occurrence of defects is empirically analyzed using financial data. In addition, it is verified whether the degree of defect occurrence varies depending on the job skill level of the direct hired personnel inputted to the construction. Through this, it will be possible to prepare an argument for revitalizing the direct construction of construction companies and an opportunity to promote it.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.8 no.11
• /
• pp.4226-4241
• /
• 2014

Cloud storage provides an easy, cost-effective and reliable way of data management for users without the burden of local data storage and maintenance. Whereas, this new paradigm poses many challenges on integrity and privacy of users' data, since users losing grip on their data after outsourcing the data to the cloud server. In order to address these problems, recently, Worku et al. have proposed an efficient privacy-preserving public auditing scheme for cloud storage. However, in this paper, we point out the security flaw existing in the scheme. An adversary, who is on-line and active, is capable of modifying the outsourced data arbitrarily and avoiding the detection by exploiting the security flaw. To fix this security flaw, we further propose a secure and efficient privacy-preserving public auditing scheme, which makes up the security flaw of Worku et al.'s scheme while retaining all the features. Finally, we give a formal security proof and the performance analysis, they show the proposed scheme has much more advantages over the Worku et al.'s scheme.