• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권2호
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• pp.1043-1063
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• 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.

• 정보보호학회논문지
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• 제25권1호
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• pp.75-82
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• 2015

최근 클라우드에 원격 저장된 데이터의 무결성 검증을 위해 제 3의 감사자에게 감사 임무를 위탁할 수 있는 다양한 공공 감사 기법이 제안되었으며, 검증 효율성을 높이기 위해 위탁받은 다중 감사 임무를 한 번에 수행할 수 있는 일괄 감사 기법 또한 제안되었다. 하지만 하나의 데이터라도 손상된 경우 일괄 감사의 검증은 실패하게 되고 포함된 모든 감사 임무를 다시 개별적으로 수행해야 한다는 문제점을 가진다. 일괄 감사는 여러 사용자의 데이터 인증자들이 복잡하게 합쳐져 있으므로 일괄 감사가 실패하는 경우 손상된 데이터를 식별하는 것은 매우 어려운 문제이다. 본 논문에서는 프라이버시 보존 가능한 공공 감사 기법인 Wang 등의 기법을 다중 클라우드의 다중 사용자에 대한 일괄 감사가 가능하도록 확장하고, 다중 클라우드 중에서 단일 클라우드의 데이터만 손상된 경우 해당 클라우드를 식별할 수 있는 기법을 제안한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권4호
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• pp.2198-2222
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• 2019

The cloud storage service becomes a rising trend based on the cloud computing, which promotes the remote data integrity auditing a hot topic. Some research can audit the integrity and correctness of user data and solve the problem of user privacy leakage. However, these schemes cannot use fewer data blocks to achieve better auditing results. In this paper, we figure out that the random sampling used in most auditing schemes is not well apply to the problem of cloud service provider (CSP) deleting the data that users rarely use, and we adopt the probability proportionate to size sampling (PPS) to handle such situation. A new scheme named improving audit efficiency of remote data for cloud storage is designed. The proposed scheme supports the public auditing with fewer data blocks and constrains the server's malicious behavior to extend the auditing cycle. Compared with the relevant schemes, the experimental results show that the proposed scheme is more effective.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권10호
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• pp.5039-5061
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• 2017

Cloud storage becomes a new trend that more and more users move their data to cloud storage servers (CSSs). To ensure the security of cloud storage, many cloud auditing schemes are proposed to check the integrity of users' cloud data. However, most of them are based on public key infrastructure, which leads to complex certificates management and verification. Besides, most existing auditing schemes are inefficient when user uploads a large amount of data or a third party auditor (TPA) performs auditing for multiple users' data on different CSSs. To overcome these problems, in this paper, we propose an efficient and secure auditing scheme based on identity-based cryptography. To relieve user's computation burden, we introduce a proxy, which is delegated to generate and upload homomorphic verifiable tags for user. We extend our auditing scheme to support auditing for dynamic data operations. We further extend it to support batch auditing in multiple users and multiple CSSs setting, which is practical and efficient in large scale cloud storage system. Extensive security analysis shows that our scheme is provably secure in random oracle model. Performance analysis demonstrates that our scheme is highly efficient, especially reducing the computation cost of proxy and TPA.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권4호
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• pp.2219-2236
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• 2017

With cloud storage services, users can handle an enormous amount of data in an efficient manner. However, due to the widespread popularization of cloud storage, users have raised concerns about the integrity of outsourced data, since they no longer possess the data locally. To address these concerns, many auditing schemes have been proposed that allow users to check the integrity of their outsourced data without retrieving it in full. Yuan and Yu proposed a public auditing scheme with a deduplication property where the cloud server does not store the duplicated data between users. In this paper, we analyze the weakness of the Yuan and Yu's scheme as well as present modifications which could improve the security of the scheme. We also define two types of adversaries and prove that our proposed scheme is secure against these adversaries under formal security models.

• 정보기술과데이타베이스저널
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• 제8권1호
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• pp.67-80
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• 2001

Information Systems (IS) auditing has been know to be helpful in developing optimal IS and managing information resources successfully. The public sector of Korea has witnessed the rapidly growing demand for IS auditing. However, there is a dearth of research that evaluate the effects of IS auditing. This study assesses the impacts of IS auditing based on a process perspective. In order to evaluate the effects objectively and properly, the current study collected empirical data from 58 firms. This stuuy confirmed that IS auditing was a very effective tool for successful IS implementation. The results show that IS auditing improves “project management”, “support”, and “engineering” practices while it does not make any impact on “contract” practice. In general, IS auditing has a tremendous impact on facilitating organization’quality improvement efforts.

• 정보과학회 논문지
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• 제43권4호
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• pp.497-508
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• 2016

클라우드 스토리지를 이용하면 사용자는 시간과 장소의 제약 없이 데이터를 원격으로 위탁 및 공유할 수 있게 된다. 그러나 기존에 클라우드에 존재하는 보안상 위협과 사용자가 물리적으로 본인의 데이터를 소유하고 있지 않는다는 사실로 인해, 클라우드 스토리지 서버에 저장된 사용자 데이터에 대한 무결성 검증이 필수적으로 요구되고 있다. 최근 몇 년간 클라우드 스토리지 환경에서 공공 무결성 검증 기법을 제안하는 많은 연구들이 제안되어 왔다. 그러나 현재까지 제안된 대부분의 클라우드 공공 무결성 검증 기법의 경우 검증 단계에서 과도한 연산량이 발생하거나 안전성을 보장받지 못했다. 본 논문에서는 J. Zhang등이 제안한 자체 인증 기반 무결성 검증 기법이 두 가지 공격에 취약함을 보인 후, 이 두 가지 공격에 안전하면서도 동일한 연산 효율성을 보장하는 새로운 자체인증 기반 클라우드 무결성 검증 기법을 제안한다. 뿐만 아니라, 제안하는 기법이 세 가지 안전성 모델에서 안전함을 증명한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권11호
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• pp.5653-5672
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• 2019

In cloud computing era, an increasing number of resource-constrained users outsource their data to cloud servers. Due to the untrustworthiness of cloud servers, it is important to ensure the integrity of outsourced data. However, most of existing solutions still have challenging issues needing to be addressed, such as the identity privacy protection of users, the traceability of users, the supporting of dynamic user operations, and the publicity of auditing. In order to tackle these issues simultaneously, in this paper, we propose a traceable dynamic public auditing scheme with identity privacy preserving for cloud storage. In the proposed scheme, a single user, including a group manager, is unable to know the signer's identity. Furthermore, our scheme realizes traceability based on a secret sharing mechanism and supports dynamic user operations. Based on the security and efficiency analysis, it is shown that our scheme is secure and efficient.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권11호
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• pp.4226-4241
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• 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.

• 한국시스템다이내믹스연구
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• 제12권3호
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• pp.25-46
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• 2011

Recently, performance auditing system of governmen is carried out as most promising framework of government audit. Performance audit by the Board of Audit and Inspection of Korea involves assessing the causes and effects of government policies, programs, and Institutions with the criteria of economy, efficiency, effectiveness. Performance auditing will contribute to strengthening the values of objective assessments of whether public resources are responsibly and effectively managed to achieve intended results. Nevertheless, there seems to be a problems appears in implementation of audit. That is the problems of tendency return to legitimacy audit which is result from the lack of strong approach and methodology. So, this study purpose to developing stronger audit concepts and methods that add to the process and framework of traditional performance auditing system. First, this study evaluates the limitation of current performance auditing system with the perspective of systems thinking. Second, this study analyzes the process and method of current system and develop the conceptual model of the Dynamics Audit System using the system dynamics methodology, which focused on the appropriate auditing process and framework.