• Journal of Industrial Technology
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• v.24 no.B
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• pp.193-198
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• 2004

We propose and analyse a flexible secure file sharing scheme which can be used for data sharing among members in P2P environment. When a member wants to share data, notification messages are sent to the members with whom the member wants to share data. Each notification message includes one-time password encrypted with the receiver's public key. A member who received the notification message can download the data by using the one-time password. The proposed scheme provides selective sharing, download confirmation and efficient memory management. In terms of security, the proposed scheme supports authentication, entity privacy, replay attack protection and disguise prevention.

• Journal of Korea Multimedia Society
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• v.25 no.9
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• pp.1291-1306
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• 2022

The dual image-based reversible data hiding scheme embeds secret data into two images to increase the embedding capacity of secret data. The dual image-based reversible data hiding scheme can transmit a lot of secret data. Therefore, various schemes have been proposed until recently. In 2021, Chen and Hong proposed a dual image-based reversible data hiding scheme that embeds a large amount of secret data using a reference matrix, secret data, and bit values. However, in this paper, more secret data can be embedded than Chen and Hong's scheme. To achieve this goal, the proposed scheme generates polynomials and shared values using secret sharing scheme, and embeds secret data using reference matrix and septenary number, and random value. Experimental results show that the proposed scheme can transmit more secret data to the receiver while maintaining the image quality similar to other dual image-based reversible data hiding schemes.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2006.06a
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• pp.765-773
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• 2006

In ubiquitous environment, private enterprise or public institution's privacy data are sometimes exposed to hackers because of the lack of the sense of information security. We apply secret sharing scheme to solve the privacy problems. But, the existing secret sharing scheme are not suitable for the management of large a quantity of data because that required operation of large capacity. In this paper, We propose new secret sharing scheme for privacy data management. Our scheme makes high-speed operation possible, and it also allows for set weight for each secret pieces depending on weight of participants. The scheme proposed in this paper makes it efficient to collect and manage secure privacy data in ubiquitous environment.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.4
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• pp.61-70
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• 2005

We propose and implement a flexible secure peer-to-peer(P2P) file sharing scheme which can be used for data sharing among closed user group (CUG) members. When a member wants to share data, notification messages are sent to the members with whom the member wants to share data. Each notification message includes one-time password encrypted with the receiver's public key. A member who received the notification message can download the data by using the one-time password. The proposed scheme provides selective sharing, download confirmation and efficient storage management. In terms of security, the proposed scheme supports authentication, entity privacy, replay attack protection and disguise prevention. We also implement the proposed system and find that the system is very useful among P2P service of closed user groups.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.7
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• pp.2703-2718
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• 2015

Nowadays, public cloud storage is gaining popularity and a growing number of users are beginning to use the public cloud storage for online data storing and sharing. However, how the encrypted data stored in public clouds can be effectively shared becomes a new challenge. Proxy re-encryption is a public-key primitive that can delegate the decryption right from one user to another. In a proxy re-encryption system, a semi-trusted proxy authorized by a data owner is allowed to transform an encrypted data under the data owner's public key into a re-encrypted data under an authorized recipient's public key without seeing the underlying plaintext. Hence, the paradigm of proxy re-encryption provides a promising solution to effectively share encrypted data. In this paper, we propose a new certificate-based proxy re-encryption scheme for encrypted data sharing in public clouds. In the random oracle model, we formally prove that the proposed scheme achieves chosen-ciphertext security. The simulation results show that it is more efficient than the previous certificate-based proxy re-encryption schemes.

• Journal of Korea Society of Industrial Information Systems
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• v.20 no.2
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• pp.11-18
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• 2015

As the communication technology and mobile devices develop, the need for the efficient and secure remote storage is required. And recently, many companies support cloud storages to meet the requirements of the customers. Especially in the business field where various companies collaborate, data sharing is an essential functionality to enhance their work performance. However, existing researches have not fully satisfied the requirement either efficiency and security. This paper suggests efficient and secure data sharing scheme for cloud storage by using secret sharing scheme. Proposed scheme can be applied to business collaborations and team projects.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.8
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• pp.2708-2721
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• 2014

Data outsourcing in the cloud (DOC) is a promising solution for data management at the present time, but it could result in the disclosure of outsourced data to unauthorized users. Therefore, protecting the confidentiality of such data has become a very challenging issue. The conventional way to achieve data confidentiality is to encrypt the data via asymmetric or symmetric encryptions before outsourcing. However, this is computationally inefficient because encryption/decryption operations are time-consuming. In recent years, a few DOC schemes based on secret sharing have emerged due to their low computational complexity. However, Dautrich and Ravishankar pointed out that most of them are insecure against certain kinds of collusion attacks. In this paper, we proposed a novel DOC scheme based on Shamir's secret sharing to overcome the security issues of these schemes. Our scheme can allow an authorized data user to recover all data files in a specified subset at once rather than one file at a time as required by other schemes that are based on secret sharing. Our thorough analyses showed that our proposed scheme is secure and that its performance is satisfactory.

• Journal of Korea Multimedia Society
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• v.20 no.2
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• pp.261-270
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• 2017

Data hiding is a way to hide the information in multimedia media such as images or video. The scheme proposed by Nguyen and Chang, was able to embed, extract, and restore the cover image and the secret data using Sudoku. But in the extracting phase, the occurrence of duplicate values in the reference matrix was found to decrease the embedding capacity of secret data. This paper has proposed a reversible data hiding scheme while maintaining the quality of the image to provide high embedding capacity using $7{\times}7$ Sudoku and Shamir's secret sharing scheme.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.12
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• pp.4042-4061
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• 2022

Recently, various security threats such as data leakage and data forgery have been possible in the communication and storage of data shared in the cloud environment. This paper conducted a study on the CP-ABSC scheme to solve these security threats. In the existing CP-ABSC scheme, if the data is obtained by the unsigncryption of the data user incorrectly, the identity of the data owner who uploaded the ciphertext cannot be known. Also, when verifying the leaked secret key, the identity information of the data user who leaked the secret key cannot be known. In terms of efficiency, the number of attributes can affect the ciphertext. In addition, a large amount of computation is required for the user to unsigncrypt the ciphertext. In this paper, we propose ECP-ABSC that provides data user traceability, and use it in a cloud environment to provide an efficient and secure data sharing scheme. The proposed ECP-ABSC scheme can trace and verify the identity of the data owner who uploaded the ciphertext incorrectly and the data user who leaked the secret key for the first time. In addition, the ciphertext of a constant size is output and the efficiency of the user's unsigncryption computation were improved.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.5
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• pp.1634-1652
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• 2022

Due to the increasing need for data sharing in the age of big data, how to achieve data access control and implement user permission revocation in the blockchain environment becomes an urgent problem. To solve the above problems, we propose a novel blockchain-based data sharing scheme (BDSS) with fine-grained access control and permission revocation in this paper, which regards the medical environment as the application scenario. In this scheme, we separate the public part and private part of the electronic medical record (EMR). Then, we use symmetric searchable encryption (SSE) technology to encrypt these two parts separately, and use attribute-based encryption (ABE) technology to encrypt symmetric keys which used in SSE technology separately. This guarantees better fine-grained access control and makes patients to share data at ease. In addition, we design a mechanism for EMR permission grant and revocation so that hospital can verify attribute set to determine whether to grant and revoke access permission through blockchain, so it is no longer necessary for ciphertext re-encryption and key update. Finally, security analysis, security proof and performance evaluation demonstrate that the proposed scheme is safe and effective in practical applications.