• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.1
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• pp.46-55
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• 2009

We study the problem of searching documents containing each of several keywords (conjunctive keyword search) over encrypted documents. A conjunctive keyword search protocol consists of three entities: a data supplier, a storage system such as database, and a user of storage system. A data supplier uploads encrypted documents on a storage system, and then a user of the storage system searches documents containing each of several keywords. Recently, many schemes on conjunctive keyword search have been suggested in various settings. However, the schemes require high computation cost for the data supplier or user storage. Moreover, up to now, their securities have been proved in the random oracle model. In this paper, we propose efficient conjunctive keyword search schemes over encrypted documents, for which security is proved without using random oracles. The storage of a user and the computational and communication costs of a data supplier in the proposed schemes are constant. The security of the scheme relies only on the hardness of the Decisional Bilinear Diffie-Hellman (DBDH) problem.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.1
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• pp.87-97
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• 2005

A secure index search protocol let us search the index of encrypted documents using the trapdoor for a keyword. It enables an untrusted server to learn nothing more than the search result about the documents without revealing the keyword. A lot of secure search protocols have been suggested but they only considered the search between a single-user and a server. In real organizations such as government offices or enterprises where exist many hierarchical departments, the search system for groups is arisen more often. In this paper, we construct secure index search protocols for hierarchical group settings without re-encryption of the old encrypted documents when group keys are re-keyed newly.

• Journal of Internet Computing and Services
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• v.11 no.4
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• pp.143-158
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• 2010

The illegal leakage of enterprise digital confidential information will threaten the enterprise with bankruptcy. Today since most small-and-medium companies have no capability to fight against illegally compromising their critically confidential documents in spite of knowing the leakage of them, strongly safe distribution system of the digital confidential documents should be designed so in secure as to prevent any malicious intent of embezzlement from accessing the critical information. Current DRM-based protection system is not always perfect to protect the digital secrets, even seems to leave the secrets open. Therefore our study has analyzed the illegal leakage paths that hackers attack against and the vulnerability of the current protection systems. As result, we study the group communication based system architecture satisfying the security conditions to make even legitimate working employee keep out of the confidential documents, without performance degradation. The main idea of this architecture is to stay every secrets in encrypted form; to isolate the encrypted documents from the crypto-key; to associate every entity with one activity and to authenticate every entity with DSA-based public key system; multiple authentication method make hackers too busy to get a privilege to access the secrets with too many puzzle pieces. This paper deal with the basic architectural structure for the above issues.

• The Journal of Korean Institute of Next Generation Computing
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• v.13 no.2
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• pp.7-17
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• 2017

In this paper, we propose the TPS (TPM-enhanced Privacy Protection System) which is an automated privacy protection system enhanced with a TPM (Trusted Platform Module). The TPS detects documents including personal information by periodic scanning the disk of clients at regular intervals and encrypts them. Hence, system manages the encrypted documents in the server. In particular, the security of TPS was greatly enhanced by limiting the access of documents including the personal information with regard to the client in an abnormal state through the TPM-based platform verification mechanism of the client system. In addition, we proposed and implemented a VTF (Virtual Trusted File) interface to provide users with the almost identical user interface as general document access even though documents containing personal information are encrypted and stored on the remote server. Consequently, the TPS automates the compliance of the personal information protection acts without additional users' interventions.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.11
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• pp.1983-1988
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• 2006

There are gradually built on electronic commerce and business information system for the effective and automated use of internet while the mainstream of industry moves on information. It is necessary that a company should develop a electronic approval system because the business documents have application to an electronic commerce, business information system as well Currently, electronic approval system on groupware is using the way of inserting the image of an approval signature, which is vulnerable on a security by attacks of fraudulent use of electrical signature and eavesdropping on electronic documents. In this paper, we implementation XML form generator based on DTD having business documents structure for creating a valid business XML documents. we designed electronic approval system based on secured XML which transfers encrypted documents. For the security issues of written XML business documents, it makes use of the crypto algorithm having high performance transaction by the interchange of public key between a server and a client.

• International Journal of Computer Science & Network Security
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• v.21 no.12
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• pp.65-74
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• 2021

Digital image processing and retrieving have increasingly become very popular on the Internet and getting more attention from various multimedia fields. That results in additional privacy requirements placed on efficient image matching techniques in various applications. Hence, several searching methods have been developed when confidential images are used in image matching between pairs of security agencies, most of these search methods either limited by its cost or precision. This study proposes a secure and efficient method that preserves image privacy and confidentially between two communicating parties. To retrieve an image, feature vector is extracted from the given query image, and then the similarities with the stored database images features vector are calculated to retrieve the matched images based on an indexing scheme and matching strategy. We used a secure content-based image retrieval features detector algorithm called Speeded-Up Robust Features (SURF) algorithm over public cloud to extract the features and the Honey Encryption algorithm. The purpose of using the encrypted images database is to provide an accurate searching through encrypted documents without needing decryption. Progress in this area helps protect the privacy of sensitive data stored on the cloud. The experimental results (conducted on a well-known image-set) show that the performance of the proposed methodology achieved a noticeable enhancement level in terms of precision, recall, F-Measure, and execution time.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.1
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• pp.149-157
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• 2003

Recently, the Internet enhanced by development of IT makes the processing and exchanging of information, As the Internet is sending and receiving digitized documents over the Internet e-mail system. The security of document information is being threated when exchanging digitized documents over an open network such as the Internet. The degree of threat is even higher when sensitive documents are involved Therefore, in this paper, the secure e-mail system on a client is designed and implemented in order to make secure exchanging of digitized documents. By using the public key infrastructure in which encrypted mail transmission, proof of delivery and integrity of the message are garanted, unauthorized manipulation, illegal acquisition and mutual authentication problem can be prevented in order to secure the document information which is crucial and sensible when exchanging the digitized document over the Internet. Futhenmore, by using the SET protocol based on public key cryptography, the secure mail system is designed and implemented in order for the users not having any professional knowledge to deal with the system easily and friendly in GUI environment.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.5
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• pp.1328-1342
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• 2013

Searchable encryption is a cryptographic protocol for searching a document in encrypted databases. A simple searchable encryption protocol, which is capable of using only one keyword at one time, is very limited and cannot satisfy demands of various applications. Thus, designing a searchable encryption with useful additional functions, for example, conjunctive keyword search, is one of the most important goals. There have been many attempts to construct a searchable encryption with conjunctive keyword search. However, most of the previously proposed protocols are based on public-key cryptosystems which require a large amount of computational cost. Moreover, the amount of computation in search procedure depends on the number of documents stored in the database. These previously proposed protocols are not suitable for extremely large data sets. In this paper, we propose a new searchable encryption protocol with a conjunctive keyword search based on a linked tree structure instead of public-key based techniques. The protocol requires a remarkably small computational cost, particularly when applied to extremely large databases. Actually, the amount of computation in search procedure depends on the number of documents matched to the query, instead of the size of the entire database.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.5
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• pp.972-977
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• 2003

XML has weakness problems on document modulation and elimination of data Because of the XML gives priority to present data format, XML signature, XML encryption, or XML access control is provided to overcome those weakness problems. However, structured XML efficiency contravention problem occurred from XML encryption and absence of protection from DID attack are still remains unsolved. In this paper, we suggests the XML schema that satisfies both validity and encryption. The DTD is unnecessary because XML schema supports Well-Formed XML documents and include meta information. Also XML schema has possibility to generate each XML document dynamically and because of self efficiency investigator rule, it has an advantage on extendability of DID based encryption of XML documents.

• Convergence Security Journal
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• v.13 no.1
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• pp.51-57
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• 2013

RSA is the most widely used public key algorithms. Payment via the SSL communications, and user authentication using RSA secure shopping mall that can protect the user's valuable information in the process of building. SSL-based electronic signature technology and encryption protocols for this technology are electronic documents are delivered to the other party through a separate encryption process, the information sender to enter information on a web browser (user) and the recipient (the Web server of the site Manager), except you will not be able to decrypt the contents. Therefore, the information is encrypted during the transfer of electronic documents even if hackers trying to Sniffing because its contents can never understand. Of internet shopping mall in the user authentication 'and' Communications' SSL secure shopping mall built with the goal of the methodology are presented.