• Journal of Industrial Convergence
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• v.21 no.9
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• pp.49-56
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• 2023

ID is used as identifying information and password as user authentication for ID-based authentication. In order to have a secure user authentication, the password is generated as a hash value on the client and sent to the server, where it is compared with the stored information and authentication is performed. However, if even one character is incorrect, the different hash value is generated, authentication will be failed and cannot be performed and various functions cannot be applied to the password. In this study, we generate several hash value including imaginary number of entered password and transmit to server and perform authentcation. we propose a technique can grants the right differentially to give various rights to the user who have many rights by one account. This can defend shoulder surfing attack by imaginary password and provide convenience to users who have various rights by granting right based on password.

• Convergence Security Journal
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• v.18 no.2
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• pp.11-17
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• 2018

Lamport's one-time password (OTP) was originally proposed to address the weaknesses of a simple password system: fixed password, pre-shared password. However, a main weakness of Lamport's OTP is that a root hash value of a new hash chain should be re-registered after consuming all the hash values since OTP generation is based on the finite hash chain. Several studies have been conducted to solve these drawbacks, but new drawbacks such as increased burden of proof for verifiers and verifiers have been exposed. In this paper, we propose and compare a novel OTP that overlaps several short hash chains instead of one long hash chain, which is the core of existing Lamport OTP, to solve the drawbacks while maintaining the advantages of Lamport.

• The KIPS Transactions:PartD
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• v.12D no.3 s.99
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• pp.499-506
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• 2005

A hash chain is a structure organized by hash function with high speed in computation. Systems using the hash chain are using extensively in various cryptography applications such as one-time passwords, server-supported signatures and micropayments. However, the most hash chain based on the system using pre-paid method provides anonymity but has the problem to increase payment cost. In this paper, we propose a new hash chain based on the micropayment system to keep user anonymity safe through blind signature in the withdrawal process of the root value without disclosing privacy information, and to improve efficiency by using secret key instead of public key in the system without the role of certificate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.12C
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• pp.995-1003
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• 2010

The content-based hashing for authentication and copy protection of image, video and 3D model has to satisfy the robustness and the security. For the security analysis of the hash value, the modelling method based on differential entropy had been presented. But this modelling can be only applied to the image hashing. This paper presents the modelling for the security analysis of the hash feature value in 3D model hashing based on differential entropy. The proposed security analysis modeling design the feature extracting methods of two types and then analyze the security of two feature values by using differential entropy modelling. In our experiment, we evaluated the security of feature extracting methods of two types and discussed about the trade-off relation of the security and the robustness of hash value.

• Journal of Yeungnam Medical Science
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• v.39 no.2
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• pp.98-107
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• 2022

Background: Stroke patients usually experience damage to multiple functions and a long rehabilitation period. Hence, there is a large volume of patient clinical information. It thus takes a long time for clinicians to identify the patient's information and essential pieces of information may be overlooked. To solve this, we stored the essential clinical information of stroke patients in a blockchain and implemented the blockchain technology using the Java programming language. Methods: We created a mini blockchain to store the medical information of patients using the Java programming language. Results: After generating a unique pair of public/private keys for identity verification, a patient's identity is verified by applying the Elliptic Curve Digital Signature Algorithm based on the generated keys. When the identity verification is complete, new medical data are stored in the transaction list and the generated transaction is verified. When verification is completed normally, the block hash value is derived using the transaction value and the hash value of the previous block. The hash value of the previous block is then stored in the generated block to interconnect the blocks. Conclusion: We demonstrated that blockchain can be used to store and deliver the patient information of stroke patients. It may be difficult to directly implement the code that we developed in the medical field, but it can serve as a starting point for the creation of a blockchain system to be used in the field.

• The Journal of Information Systems
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• v.27 no.2
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• pp.77-94
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• 2018

Purpose As the amount of data became enormous, it became a time when more efforts were needed to find the necessary information. Curation is a new term similarly to the museum curator, which is a service that helps people to collect, share, and value the contents of the Internet. In SNS, hash tag is used for emotional vocabulary to be transmitted between users by using (#) tag. Design/methodology/approach As the amount of data became enormous, it became a time when more efforts were needed to find the necessary information. Curation is a new term similarly to the museum curator, which is a service that helps people to collect, share, and value the contents of the Internet. In SNS, hash tag is used for emotional vocabulary to be transmitted between users by using (#) tag. Findings This study base on seven emotional sets such as 'Happy', 'Angry', 'Sad', 'Bad', 'Fearful', 'Surprised', 'Disgusted' to construct 327 emotional seeds and utilize the autofill function of web browser to collect 1.5 million emotional words from emotional seeds. The emotional dictionary of this study is considered to be meaningful as a tool to make emotional judgment from unstructured data.

• Journal of KIISE:Information Networking
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• v.32 no.4
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• pp.462-470
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• 2005

A hash chain is highly efficient and attractive structure to use in electronic cash. Previous systems using hash chain are used extensively in various cryptography applications such as one-time passwords, server-supported signatures and microments. However, The most hash chain based systems using fro-paid method provide anonymity but have the problem to increase payment cost. Therefore, in this paper, we propose a new hash chain based microment system which improves efficiency using session key and guarantees user anonymity through blind signature in the withdrawal process of the root value without disclosing privacy Information.

• Journal of Platform Technology
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• v.10 no.4
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• pp.39-46
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• 2022

Recently, digital contents including video and sound are created in various fields, transmitted to the cloud through the Internet, and then stored and used. In order to utilize digital content, it is essential to verify data integrity, and it is necessary to ensure network bandwidth efficiency of verified data. This paper describes the design and implementation of a server that maintains, manages, and provides data for verifying the integrity of video data. The server receives and stores image data from Logger, a module that acquires image data, and performs a function of providing data necessary for verification to Verifier, a module that verifies image data. Then, a lightweight Merkle tree is constructed using the hash value. The light-weight Merkle tree can quickly detect integrity violations without comparing individual hash values of the corresponding video frame changes of the video frame indexes of the two versions. A lightweight Merkle tree is constructed by generating a hash value of digital content so as to have network bandwidth efficiency, and the result of performing proof of integrity verification is presented.

• Journal of the Korea Society of Computer and Information
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• v.18 no.6
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• pp.47-54
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• 2013

In this paper, we proposed an efficient digital authentication service system for the vehicle data collected from digital tachograph. In domestic, There is no method available to verify that information has not been forged and reliable information for collected vehicle data. The proposed method in this paper can prove transmitted vehicle data that have not been forged using the signature value. The signature value of digital authentication is produced with the digital signature generation key after obtaining the hash value of vehicle data. It is achieved through checking the stored hash value and the hash value match that is obtained with the digital signature verification key from the digital signature value. We confirmed the proposed system can ensure reliability of vehicle data through the system implementation and experiment.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.6
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• pp.175-184
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• 2022

Blockchain is being studied in various fields such as logistics, fintech, medical care, and the public sector. In the public information software project, some deliverables are omitted because the developed deliverables and the deliverables requested by the project management methodology do not match, and an additional process is required for payment. In this paper, we propose the deliverables management system for public information software project which is configured a distributed environment using the Ethereum blockchain and which has an automatic payment system only when all deliverables are approved. This system can keep the service available in case of system failure, provide transparency and traceability of deliverables management, and can reduce conflicts between the ordering company and the contractor through automatic payment. In this system, the information of deliverables is stored in the blockchain, and the deliverables that their file name is the hash value calculated by using the version information and the hash value of the previous version deliverable, are stored in the SFTP server. Experimental results show that the hash value of the deliverables registered by the contractor is correct, the file name of the deliverables stored in the SFTP server is the same as the hash value registered in the Ethereum blockchain, and the payment is made automatically to the Ethereum address of the contractor when all deliverables are approved.