• ETRI Journal
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• v.38 no.1
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• pp.123-132
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• 2016

The Boneh, Goh, and Nissim (BGN) cryptosytem is the first homomorphic encryption scheme that allows additions and multiplications of plaintexts on encrypted data. BGN-type cryptosystems permit very small plaintext sizes. The best-known approach for the expansion of a message size by t times is one that requires t implementations of an initial scheme; however, such an approach becomes impractical when t is large. In this paper, we present a method of message expansion of BGN-type homomorphic encryption using composite product pairing, which is practical for relatively large t. In addition, we prove that the indistinguishability under chosen plaintext attack security of our construction relies on the decisional Diffie-Hellman assumption for all subgroups of prime order of the underlying composite pairing group.

• Convergence Security Journal
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• v.2 no.1
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• pp.49-57
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• 2002

Real-Time Protocol (RTP) is used for multimedia information transmission and RTP payload must be encrypted for providing multimedia information security. Encryption/decryption delay is minimized, because there are constraints in transporting a multimedia data through the Internet. Therefore, encryption algorithm is changed with considering network traffic and load. During many users participate in the same multimedia service, an user who already left the service can receive and decrypt the RTP payload because of knowing the encryption key. In this paper, Security Control Protocol for RTP is designed and implemented for changing the encryption algorithm and the key.

• Annual Conference of KIPS
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• 2013.11a
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• pp.906-909
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• 2013

The Semantic Web is leading us to a world of information sharing by enabling distributed knowledge aggregation and creation. RDF is the foundations of the Semantic Web. For secure Semantic web we need to secure RDF as well. Unauthorized access to an RDF document can change or damage its semantics or manipulate the relations between resources. This article includes the study of RDF security issues and analysis of the existing solutions. After finding limitations of existing solution, a hybrid approach has been proposed.

• Journal of the Korean Association of Geographic Information Studies
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• v.26 no.4
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• pp.67-79
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• 2023

Service environments through laptops, smart devices, and various IoT devices are developing very rapidly. Recent security measures in these Internet environments mainly consist of network application level solutions such as firewall(Intrusion Prevention Systems) and IDS (intrusion detection system). In addition, various security data have recently been used on-site, and issues regarding the management and destruction of such security data have been raised. Products such as DRM(Digital Rights Management) and DLP(Data Loss Prevention) are being used to manage these security data. However despite these security measures, data security measures taken out to be used in the field are operated to the extent that the data is encrypted, delivered, and stored in many environments, and measures for encryption key management or data destruction are insufficient. Based on these issues we aim to propose a SecureOS Module, an OS-based security module. With this module users can manage and operate security data through a consistent interface, addressing the problems mentioned above.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.10
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• pp.118-127
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• 2014

DNA data storage refers to any technique for storing massive digital data in base sequence of DNA and has been recognized as the future storage medium recently. This paper presents an information hiding method for DNA data storage that the massive data is hidden in non-coding strand based on DNA steganography. Our method maps the encrypted data to the data base sequence using the numerical mapping table and then hides it in the non-coding strand using the key that consists of the seed and sector length. Therefore, our method can preserve the protein, extract the hidden data without the knowledge of host DNA sequence, and detect the position of mutation error. Experimental results verify that our method has more high data capacity than conventional methods and also detects the positions of mutation errors by the parity bases.

• Journal of Korea Multimedia Society
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• v.2 no.2
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• pp.155-165
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• 1999

Because the encrypted data is random, there is a possibility of threat that attacker reveals the secret data. On the other hand, as the image steganogrphy is to embed the secret data into cover image and to transmit the embedded image to receiver, an attacker could not know the existence of secret data even though he/she sees the embedded image, therefore the sender may reduce the threat of attack. In the image steganography, the secret data is embedded by modifying value of pixels as a form of noise. If the secret data is embedded into gray image, the degradation of image quality results from the modifications of image due to noise. Therefore many methods have been proposed to embed the secret data while dethering the gray image, but the existing method using error-diffusion has a problem that any patterns such as a diagonal lines or vertical take place due to embedding the secret data at the fixed interval. To solve this problem and to improve the existing method, we proposed the new method that embeds the secret data at changed point with respect to 1's run-length or at the position where has the minimum difference with the original dithered value. We evaluated the performance of the proposed method by computer simulation.

• The Journal of the Convergence on Culture Technology
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• v.10 no.1
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• pp.435-441
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• 2024

In order for the large amount of collected data sets to be used as deep learning training data, sensitive personal information such as resident registration number and disease information must be changed or encrypted to prevent it from being exposed to hackers, and the data must be reconstructed to match the structure of the built deep learning model. Currently, these tasks are performed manually by experts, which takes a lot of time and money. To solve these problems, this paper proposes a technique that can automatically perform data processing tasks to protect personal information during the deep learning process. In the proposed technique, privacy protection tasks are performed based on data generalization and data reconstruction tasks are performed using circular queues. To verify the validity of the proposed technique, it was directly implemented using C language. As a result of the verification, it was confirmed that data generalization was performed normally and data reconstruction suitable for the deep learning model was performed properly.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.12
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• pp.1904-1913
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• 2021

With the proliferation of smart phones and the development of IoT technology, it has become possible to collect personal data for public purposes. However, users are afraid of voluntarily providing their private data due to privacy issues. To remedy this problem, mainly three techniques have been studied: data disturbance, traditional encryption, and homomorphic encryption. In this work, we perform simulations to compare them in terms of accuracy, message length, and computation delay. Experiment results show that the data disturbance method is fast and inaccurate while the traditional encryption method is accurate and slow. Similar to traditional encryption algorithms, the homomorphic encryption algorithm is relatively effective in privacy preserving because it allows computing encrypted data without decryption, but it requires high computation costs as well. However, its main cost, arithmetic operations, can be processed in parallel. Also, data analysis using the homomorphic encryption needs to do decryption only once at any number of data.

• Journal of Digital Contents Society
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• v.9 no.1
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• pp.125-130
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• 2008

User web service is increasing by development of internet technology. Quantity of encrypted data that transmitted through the network are increasing by development of encipherment technology. We have many problems; it is caused by technical development and service increase of user requests. It is like that, we have reliability of contents and illegality copy problem of internet contents in web application system. It is contents protection skills in web that encipherment technology, authentication and digital signature. We need message encoding and secret key for solve vulnerability of encipherment in web application system. In this paper, we propose a distributed secure system that can data confidentiality and user authentication. It prevent performance degradation from bottle neck in encipherment server, and improve service quality.

• 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.