• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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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.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.1
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• pp.75-82
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• 2015

Recently, many public auditing schemes have been proposed to support public auditability that enables a third party auditor to verify the integrity of data stored in the remote cloud server. To improve the performance of the auditor, several public auditing schemes support batch auditing which allows the auditor to handle simultaneously multiple auditing delegations from different users. However, when even one data is corrupted, the batch auditing will fail and individual and repeated auditing processes will be required. It is difficult to identify the corrupted data from the proof in which distinct data blocks and authenticators of distinct users are intricately aggregated. In this paper, we extend a public auditing scheme of Wang et al. to support batch auditing for multi-cloud and multi-user. We propose an identification scheme of the corrupted cloud when the data of a single cloud is corrupted in the batch auditing of multi-cloud and multi-user.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.4
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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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• v.11 no.10
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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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• v.11 no.4
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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.

• The Journal of Information Technology and Database
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• v.8 no.1
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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.

• Journal of KIISE
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• v.43 no.4
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• pp.497-508
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• 2016

With a cloud storage service, data owners can easily access their outsourced data in cloud storage on different devices and at different locations, and can share their data with others. However, as the users no longer physically have possession of their outsourced data and the cloud still facing the existence of internal/external threats, the task of checking the data integrity is formidable. Over recent years, numerous schemes have been proposed to ensure data integrity in an untrusted cloud. However, the existing public auditing schemes use a third-party auditor(TPA) to execute high computation to check data integrity and may still face many security threats. In this paper, we first demonstrate that the scheme proposed by Zhang et al. is not secure against our two threat models, and then we propose a self-certified public auditing scheme to eliminate the security threats and guarantee a constant communication cost. Moreover, we prove the securities of our public auditing scheme under three security models.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.11
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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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• v.8 no.11
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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.

• Korean System Dynamics Review
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• v.12 no.3
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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.