• Journal of the Korea Society of Computer and Information
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• v.28 no.3
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• pp.59-65
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• 2023

As research on blockchain applications in various fields is actively increasing, management of private keys that prove users of blockchain has become important. If you lose your private key, you lose all your data. In order to solve this problem, previously, blockchain wallets, private key recovery using partial information, and private key recovery through distributed storage have been proposed. In this paper, we propose a safe private key backup and recovery method using Shamir's Secrete Sharing (SSS) scheme and biometric information, and evaluate its safety. In this paper, we propose a safe private key backup and recovery method using Shamir's Secrete Sharing (SSS) scheme and biometric information, and evaluate its safety against robustness during message exchange, replay attack, man-in-the-middle attack and forgery and tampering attack.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.12
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• pp.4725-4747
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• 2020

Software defined networking (SDN) is considered to be one of the most promising paradigms in the future. To solve the scalability and performance problem that a single and centralized controller suffers from, the distributed multi-controller architecture is adopted, thus forms multi-domain SDN. In a multi-domain SDN network, it is of great importance to ensure a reliable control plane. In this paper, we focus on the reliability problem of multi-domain SDN against controller failure from perspectives of backup controller deployment and controller replication. We firstly propose a placement algorithm for backup controllers, which considers both the reliability and the cost factors. Then a controller replication mechanism based on shared data storage is proposed to solve the inconsistency between the active and standby controllers. We also propose a shared data storage layout method that considers both reliability and performance. Besides, a fault recovery and repair process is designed based on the controller backup and shared data storage mechanism. Simulations show that our approach can recover and repair controller failure. Evaluation results also show that the proposed backup controller placement approach is more effective than other methods.

• The KIPS Transactions:PartC
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• v.16C no.3
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• pp.335-346
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• 2009

Mobile environments are evolving the main communication environment as a develops of communication technology. In mobile environments, sensitive information can be compromised on-line, so demand for security has increased. Also, mobile devices that provide various services are in danger from malware and illegal devices, phishing and sniffing etc, and the privacy. Therefore, MTM(Mobile Trusted Module) is developed and promoted by TCG(Trusted Computing Group), which is an industry standard body to enhance the security level in the mobile computing environment. MTM protects user privacy and platform integrity, because it is embedded in the platform, and it is physically secure. However, a security approach is required when secret data is migrated elsewhere, because MTM provides strong security functions. In this paper, we analyze the TCG standard and migration method for cryptographic key, then we propose a secure migration scheme for cryptographic key using key Backup/Recovery method.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.4
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• pp.1911-1930
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• 2017

Overlay routing has emerged as a promising approach to improve reliability and efficiency of the Internet. The key to overlay routing is the placement and maintenance of the overlay infrastructure, especially, the selection and placement of key relay nodes. Spurred by the observation that a few relay nodes with high betweenness centrality can provide more optimal routes for a large number of node pairs, we propose a resilient routing overlay network construction method by introducing Super-Relay nodes. In detail, we present the K-Minimum Spanning Tree with Super-Relay nodes algorithm (SR-KMST), in which we focus on the selection and connection of Super-Relay nodes to optimize the routing quality in a resilient and scalable manner. For the simultaneous path failures between the default physical path and the overlay backup path, we also address the selection of recovery path. The objective is to select a proper one-hop recovery path with minimum cost in path probing and measurement. Simulations based on a real ISP network and a synthetic Internet topology show that our approach can provide high-quality overlay routing service, while achieving good robustness.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.9
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• pp.4023-4043
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• 2016

Network virtualization has been regarded as a core attribute of the Future Internet. In a network virtualization environment (NVE), multiple heterogeneous virtual networks can coexist on a shared substrate network. Thus, a substrate network failure may affect multiple virtual networks. In this case, it is increasingly critical to provide survivability for the virtual networks against the substrate network failures. Previous research focused on mechanisms that ensure the resilience of the virtual network. However, the resource efficiency is still important to make the mapping scheme practical. In this paper, we study the survivable virtual network embedding mechanisms against substrate link and node failure from the perspective of improving the resource efficiency. For substrate link survivability, we propose a load-balancing and re-configuration strategy to improve the acceptance ratio and bandwidth utilization ratio. For substrate node survivability, we develop a minimum cost heuristic based on a divided network model and a backup resource cost model, which can both satisfy the location constraints of virtual node and increase the sharing degree of the backup resources. Simulations are conducted to evaluate the performance of the solutions. The proposed load balancing and re-configuration strategy for substrate link survivability outperforms other approaches in terms of acceptance ratio and bandwidth utilization ratio. And the proposed minimum cost heuristic for substrate node survivability gets a good performance in term of acceptance ratio.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.3
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• pp.861-876
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• 2022

Cryptoassets such as Bitcoin and Ethereum are widely traded around the world. Cryptocurrencies are also transferred between investors. Cryptocurrency has become a new and attractive means of remittance. Thus, blockchain-based smart contracts also attract attention when central banks design digital currencies. However, it has been discovered that a significant amount of cryptoassets on blockchain are lost or stranded for a variety of reasons, including the loss of the private key or the owner's death. To address this issue, we propose a method for recoverable transactions that would replace the traditional transaction by allowing cryptoassets to be sent to a backup account address after a deadline has passed. We provide the computational workload required for our method by analyzing the prototype. The method proposed in this paper can be considered as a good model for digital currency design, including central bank digital currency (CBDC).

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.3
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• pp.429-438
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• 2021

The mandatory installation of the ECDIS (Electronic Chart Display and Information System) became an important navigational equipment for navigation officer. In addition, ECDIS is a key component of the ship's digitalization in conjunction with various navigational equipment. Meanwhile, cyber-attacks emerge as a new threat along with digitalization. Damage caused by cyber-attacks is also reported in the shipping sector, and IMO recommends that cybersecurity guidelines be developed and included in International Security Management (ISM). This study analyzed the cybersecurity hazards of ECDIS, where various navigational equipment are connected. To this end, Importance-Performance Analysis (IPA) was conducted on navigation officer using ECDIS. As a result, the development of technologies for cyber-attack detection and prevention should be priority. In addition, policies related to 'Hardware and Software upgrade', 'network access control', and 'data backup and recovery' were analyzed as contents to be maintained. This paper is significant in deriving risk factors from the perspective of ECDIS users and analyzing their priorities, and it is necessary to analyze various cyber-attacks that may occur on ships in the future.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7B
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• pp.605-619
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• 2003

The main memory DBMS(MMDBMS) efficiently supports various database applications that require high performance since it employs main memory rather than disk as a primary storage. In this paper, we discuss the index manager of the Tachyon, a next-generation MMDBMS. Recently, the gap between the CPU processing and main memory access times is becoming much wider due to rapid advance of CPU technology. By devising data structures and algorithms that utilize the behavior of the cache in CPU, we are able to enhance the overall performance of MMDBMSs considerably. In this paper, we address the practical implementation issues and our solutions for them obtained in developing the cache-conscious index manager of the Tachyon. The main issues touched are (1) consideration of the cache behavior, (2) compact representation of the index entry and the index node, (3) support of variable-length keys, (4) support of multiple-attribute keys, (5) support of duplicated keys, (6) definition of the system catalog for indexes, (7) definition of external APIs, (8) concurrency control, and (9) backup and recovery. We also show the effectiveness of our approach through extensive experiments.