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Dr. Nam-Su Jho
Electronics and Telecommunications Research Institute (ETRI)

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0 Cryptography
0 Data Encryption
0 Quantum cryptography
0 Block Chain
0 Privacy & Security

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Journal article
Published: 10 December 2020 in Sustainability
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For secure location proof in many applications, distance bounding protocols are considered as one of the useful tools that can be used in practice. In distance bounding protocols, a prover and a verifier can measure the distance between them by performing an interactive protocol. In general, the verifier is regarded as an honest service provider, and thus, an adversarial verifier is not considered for security analysis. However, we cannot ignore the possibility of the corruption of the verifier, which can spoil the prover’s privacy. To handle the security problem, a prover-anonymous and deniable distance bounding protocol is proposed, which can guarantee the privacy of the prover even though the verifier is corrupted. In this paper, we review the prover-anonymous and deniable distance bounding protocol in terms of the membership management, and we show that the communication overhead in the protocol for each membership change is O(n) where n is the number of users. Then, we propose an improved membership management technique, which can efficiently support membership change in terms of the communication overhead. The improved technique requires O(1) for each membership change instead of O(n), as in the existing protocol.

ACS Style

Nam-Su Jho; Taek-Young Youn. Dynamic Membership Management in Anonymous and Deniable Distance Bounding. Sustainability 2020, 12, 10330 .

AMA Style

Nam-Su Jho, Taek-Young Youn. Dynamic Membership Management in Anonymous and Deniable Distance Bounding. Sustainability. 2020; 12 (24):10330.

Chicago/Turabian Style

Nam-Su Jho; Taek-Young Youn. 2020. "Dynamic Membership Management in Anonymous and Deniable Distance Bounding." Sustainability 12, no. 24: 10330.

Journal article
Published: 02 June 2020 in Sensors
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Currently, “connected cars” are being actively designed over smart cars and autonomous cars, to establish a two-way communication network between the vehicle and all infrastructure. Additionally, because vehicle black boxes are becoming more common, specific processes for secure and efficient data sharing and transaction via vehicle networks must be developed. In this paper, we propose a Blockchain-based vehicle data marketplace platform model, along with a data sharing scheme, using Blockchain-based data-owner-based attribute-based encryption (DO-ABE). The proposed model achieves the basic requirements such as data confidentiality, integrity, and privacy. The proposed system securely and effectively handles large-capacity and privacy-sensitive black box video data by storing the metadata on Blockchain (on-chain) and encrypted raw data on off-chain (external) storage, and adopting consortium Blockchain. Furthermore, the data owners of the proposed model can control their own data by applying the Blockchain-based DO-ABE and owner-defined access control lists.

ACS Style

Byeong-Gyu Jeong; Taek-Young Youn; Nam-Su Jho; Sang Uk Shin; Taek-Young Youn. Blockchain-Based Data Sharing and Trading Model for the Connected Car. Sensors 2020, 20, 3141 .

AMA Style

Byeong-Gyu Jeong, Taek-Young Youn, Nam-Su Jho, Sang Uk Shin, Taek-Young Youn. Blockchain-Based Data Sharing and Trading Model for the Connected Car. Sensors. 2020; 20 (11):3141.

Chicago/Turabian Style

Byeong-Gyu Jeong; Taek-Young Youn; Nam-Su Jho; Sang Uk Shin; Taek-Young Youn. 2020. "Blockchain-Based Data Sharing and Trading Model for the Connected Car." Sensors 20, no. 11: 3141.

Journal article
Published: 29 May 2020 in Energies
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Deduplication of encrypted data is a significant function for both the privacy of stored data and efficient storage management. Several deduplication techniques have been designed to provide improved security or efficiency. In this study, we focus on the client-side deduplication technique, which has more advantages than the server-side deduplication technique, particularly in communication overhead, owing to conditional data transmissions. From a security perspective, poison, dictionary, and identification attacks are considered as threats against client-side deduplication. Unfortunately, in contrast to other attacks, identification attacks and the corresponding countermeasures have not been studied in depth. In identification attacks, an adversary tries to identify the existence of a specific file. Identification attacks should be countered because adversaries can use the attacks to break the privacy of the data owner. Therefore, in the literature, some counter-based countermeasures have been proposed as temporary remedies for such attacks. In this paper, we present an analysis of the security features of deduplication techniques against identification attacks and show that the lack of security of the techniques can be eliminated by providing uncertainness to the conditional responses in the deduplication protocol, which are based on the existence of files. We also present a concrete countermeasure, called the time-locked deduplication technique, which can provide uncertainness to the conditional responses by withholding the operation of the deduplication functionality until a predefined time. An additional cost for locking is incurred only when the file to be stored does not already exist in the server’s storage. Therefore, our technique can improve the security of client-side deduplication against identification attacks at almost the same cost as existing techniques, except in the case of files uploaded for the first time.

ACS Style

Taek-Young Youn; Nam-Su Jho; Keonwoo Kim; Ku-Young Chang; Ki-Woong Park; Taek-Young Youn. Locked Deduplication of Encrypted Data to Counter Identification Attacks in Cloud Storage Platforms. Energies 2020, 13, 2742 .

AMA Style

Taek-Young Youn, Nam-Su Jho, Keonwoo Kim, Ku-Young Chang, Ki-Woong Park, Taek-Young Youn. Locked Deduplication of Encrypted Data to Counter Identification Attacks in Cloud Storage Platforms. Energies. 2020; 13 (11):2742.

Chicago/Turabian Style

Taek-Young Youn; Nam-Su Jho; Keonwoo Kim; Ku-Young Chang; Ki-Woong Park; Taek-Young Youn. 2020. "Locked Deduplication of Encrypted Data to Counter Identification Attacks in Cloud Storage Platforms." Energies 13, no. 11: 2742.

Article
Published: 01 February 2017 in ETRI Journal
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Message-locked encryption (MLE) is a widespread cryptographic primitive that enables the deduplication of encrypted data stored within the cloud. Practical client-side contributions of MLE, however, are vulnerable to a poison attack, and server-side MLE schemes require large bandwidth consumption. In this paper, we propose a new client-side secure deduplication method that prevents a poison attack, reduces the amount of traffic to be transmitted over a network, and requires fewer cryptographic operations to execute the protocol. The proposed primitive was analyzed in terms of security, communication costs, and computational requirements. We also compared our proposal with existing MLE schemes.

ACS Style

Keonwoo Kim; Taek‐Young Youn; Nam‐Su Jho; Ku‐Young Chang; Taek-Young Youn. Client-Side Deduplication to Enhance Security and Reduce Communication Costs. ETRI Journal 2017, 39, 116 -123.

AMA Style

Keonwoo Kim, Taek‐Young Youn, Nam‐Su Jho, Ku‐Young Chang, Taek-Young Youn. Client-Side Deduplication to Enhance Security and Reduce Communication Costs. ETRI Journal. 2017; 39 (1):116-123.

Chicago/Turabian Style

Keonwoo Kim; Taek‐Young Youn; Nam‐Su Jho; Ku‐Young Chang; Taek-Young Youn. 2017. "Client-Side Deduplication to Enhance Security and Reduce Communication Costs." ETRI Journal 39, no. 1: 116-123.

Journal article
Published: 01 August 2015 in The Journal of Supercomputing
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Searchable encryption is an encryption system which provides confidentiality of stored documents and usability of document search at the same time. Remote cloud storage is the most typical application for searchable encryption. By applying searchable encryption, inside attacks can be prevented fundamentally. Designing searchable encryption which supports various queries—for example, range query, conjunctive keyword query, etc.—is also important for convenience. In this paper, we focus on range query problem. Up to now, only a few results have been proposed, in which the main functions are constructed using public key cryptosystems. Therefore, the amount of computations for encryption and search is large. Furthermore, search time depends on the size of the entire database. We propose a new searchable encryption protocol which is based on a symmetric key encryption and linked chain structure instead of public key-based techniques. The main contribution of the protocol is reducing the computation cost for search remarkably. In reality, the amount of computations depends on the number of documents that are matched to a query instead of the size of the entire database.

ACS Style

Nam-Su Jho; Ku-Young Chang; DoWon Hong; Changho Seo. Symmetric searchable encryption with efficient range query using multi-layered linked chains. The Journal of Supercomputing 2015, 72, 4233 -4246.

AMA Style

Nam-Su Jho, Ku-Young Chang, DoWon Hong, Changho Seo. Symmetric searchable encryption with efficient range query using multi-layered linked chains. The Journal of Supercomputing. 2015; 72 (11):4233-4246.

Chicago/Turabian Style

Nam-Su Jho; Ku-Young Chang; DoWon Hong; Changho Seo. 2015. "Symmetric searchable encryption with efficient range query using multi-layered linked chains." The Journal of Supercomputing 72, no. 11: 4233-4246.

Conference paper
Published: 01 January 2009 in Computer Vision
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Key pre-distribution in wireless sensor network is aimed at delivering keys to sensor networks at the low expense of computation, communication, and memory while providing a high degree of security expressed by network resiliency to node capture. In this paper, we introduce a computationally efficient construction for the symmetric matrix-based key distribution. Particularly, this work introduces an original modification over the well known DDHV scheme (by Du et al.). Our modification shows that using a specific structures for the public matrix instead of fully random matrix with elements in ℤq can reduce the computation overhead for generating the key information and the key itself at the expense of small memory overhead. Our modification guarantees the same level of security for restricted network size. We show an extensive security analysis of the provided scheme in different settings and compare to the relevant works in the literature to demonstrate its merit.

ACS Style

Abedelaziz Mohaisen; Nam-Su Jho; DoWon Hong. A Computationally-Efficient Construction for the Matrix-Based Key Distribution in Sensor Network. Computer Vision 2009, 190 -199.

AMA Style

Abedelaziz Mohaisen, Nam-Su Jho, DoWon Hong. A Computationally-Efficient Construction for the Matrix-Based Key Distribution in Sensor Network. Computer Vision. 2009; ():190-199.

Chicago/Turabian Style

Abedelaziz Mohaisen; Nam-Su Jho; DoWon Hong. 2009. "A Computationally-Efficient Construction for the Matrix-Based Key Distribution in Sensor Network." Computer Vision , no. : 190-199.