• The Journal of the Acoustical Society of Korea
• /
• v.37 no.6
• /
• pp.483-488
• /
• 2018

Far field input utterance is one of the major causes of performance degradation of speaker verification systems. In this study, we used teacher student learning framework to compensate for the performance degradation caused by far field utterances. Teacher student learning refers to training the student deep neural network in possible performance degradation condition using the teacher deep neural network trained without such condition. In this study, we use the teacher network trained with near distance utterances to train the student network with far distance utterances. However, through experiments, it was found that performance of near distance utterances were deteriorated. To avoid such phenomenon, we proposed techniques that use trained teacher network as initialization of student network and training the student network using both near and far field utterances. Experiments were conducted using deep neural networks that input raw waveforms of 4-channel utterances recorded in both near and far distance. Results show the equal error rate of near and far-field utterances respectively, 2.55 % / 2.8 % without teacher student learning, 9.75 % / 1.8 % for conventional teacher student learning, and 2.5 % / 2.7 % with proposed techniques.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.21 no.6
• /
• pp.83-99
• /
• 2011

OTP (One Time Password) is widely used for protecting accounts on Internet banking, portal services and online game services in Korea. OTP is very strong method for enforcing account security but there are several ways for exploiting vulnerabilities caused by implementation errors. These attacks can work because of the weakness from OTP enabled system's vulnerabilities, not for OTP's algorithm itself. In this paper, we present the known attack scenarios such as MITM (Man-in-the-Middle) attack and various reverse engineering techniques; also, we show the test result of the attacks and countermeasures for these attacks.

• The KIPS Transactions:PartC
• /
• v.17C no.6
• /
• pp.441-450
• /
• 2010

Recently, a lot of interest is increased in sensor network which gathers various data through many sensor nodes deployed in wired and wireless network environment. However, because of the limitation in memory, computation, and energy of the sensor nodes, security problem is very important issue. In sensor network, not only the security problem, but also computing power should be seriously considered. In this paper, considering these characteristics, we make the sensor network consist of normal sensor nodes and clusterheaders with enough space and computing power, and propose a group key rekeying scheme adopting PCGR(Predistribution and local Collaborationbased Group Rekeying) for secure group communication. In our proposal, we enhance the security by minimizing the risk to safety of the entire network through verifying the new key value from clusterheader by sensor nodes. That is, to update the group keys, clusterheaders confirm sensor nodes through verifying the information from sensor nodes and send the new group keys back to authentic member nodes. The group keys sent back by the clusterheaders are verified again by sensor nodes. Through this mutual authentication, we can check if clusterheaders are compromised or not. Qualnet simulation result shows that our scheme not only guarantees secure group key rekeying but also decreasesstorage and communication overhead.

• Journal of Korea Multimedia Society
• /
• v.8 no.9
• /
• pp.1258-1268
• /
• 2005

While the concept of Home Network is laying by and its interests are increasing by means of digitalizing of the information communication infrastructure, many efforts are in progress toward convenient lives. Moreover, as information household appliances which have a junction of connecting to the network are appearing over the past a few years, the demands against intellectual Home Services are increasing. In this paper, by being based upon Multimedia which is an essential factor for developing of various application services on ubiquitous computing environments, we suggest a simplified application model that could apply the information to the automated processing system after studying user's behavior patterns using authentication and access control for identity certification of users. In addition, we compared captured video images in the fixed range by pixel unit through some time and checked disorder of them. And that made safe of user certification as adopting self-developed certification method which was used 'Hash' algorism through salt function of 12 byte. In order to show the usefulness of this proposed model, we did some testing by emulator for control of information after construction for Intellectual Multimedia Server, which ubiquitous network is available on as a scheme so as to check out developed applications. According to experimental results, it is very reasonable to believe that we could extend various multimedia applications in our daily lives.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.21 no.4
• /
• pp.759-766
• /
• 2017

In this paper, we preserve the transparency of digital contents by compressing and storing the medical image for a certain period so as to be safe and robust against various attacks of medical images. The proposed algorithm generates an encrypted image authentication code that extracts the feature value of the original image and combines it with the user's information. in order to extract hidden data, the authentication code is first decrypts the encrypted medical image and extracts the hidden data using the spatial characteristics of image. The proposed algorithm guarantees integrity when comparing extracted authentication code and newly generated authentication code for image authentication after directly inserting it into content itself through watermarking. We have proved various security of attack of image data and proved that the certification rate is improved to 98.4%.

• Information and Communications Magazine
• /
• v.24 no.4
• /
• pp.36-48
• /
• 2007

최근 생체 인식 시스템의 보급과 함께, 생체 인식 시스템의 인증 정확도 외에 생체 데이터와 생체 인식 시스템 자체의 보안성, 그리고 개인의 프라이버시 보호에 대해 요구가 증가되고 있다. 생체 데이터와 생체 인식 시스템의 보안성 증대를 위해서는 다양한 기술이 연구되고 있는데, 본 논문에서는 (과기부지정 ERC) 생체인식센터에서 중점적으로 연구하고 있는 생체 정보 보호 기술에 대하여 소개한다. 이러한 생체 정보 보호 기술에는 생체정보가 도난 되었을 경우 그 피해를 최소화하기 위해 원래의 생체정보를 그대로 저장하는 것이 아니라 이를 바꾸어 변환된 생체정보를 저장하고 사용하는 생체 정보 변환 기술이 있다. 또한, 원래의 생체정보가 유출되고 이를 이용하여 위조 생체 등을 만들어 공격할 경우를 대비할 수 있는 위조 생체 검출 기술이 있으며, 생체정보의 유출된 출처를 찾기 위해 생체정보에 소유 책임기관 등을 표시하는 데이터 은닉 기법이 연구되고 있다. 이 외에 생체정보를 이용하여 일반적인 암호화 알고리즘에 사용되는 키를 은닉하고 생체정보를 통해 인증된 사용자에 한하여 키를 사용하도록 하는 방법도 본 논문에서 소개한다. 끝으로 이러한 생체 정보 보호 기술을 이용하여 생체 인식 시스템의 보안성을 향상시키는 방법에 대하여 논의한다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.15 no.7
• /
• pp.545-552
• /
• 1990

This paper is concerned with the file protection in the file transfer systems. In the existing file transfer systems, passwords are used in the protection but do not provide any data protection and can only provide some protection against unauthorized access. Even provided with this protection, we cannot be free form computer hackers. In order to achieve higher standards of protection for our privacy (protection for data themselves, authentication of senders...) analternative technical system should be developed in using of pulic key cryptography by choosing the public key method (RSA public key) in the file transfer. A new system suggested in the paper can achieve some higher standards of protection for our privacy. We a result thie system will be easily applied to various document handling systems as in the data base.

• Convergence Security Journal
• /
• v.11 no.4
• /
• pp.31-36
• /
• 2011

Enterprise which has a core technology or organization which manages a core information will be walking into a critical situation like a ruins when organization's confidential information is outflowed. In the past confidential information that was leaked to the off-line, recently the outflow made possible through a variety of equipment at any time via the network based on the ubiquitous communication environment. In this paper, we propose to authenticate and block all packets transmitted via the network at real-time in order to prevent confidentials outflow. Especially in or der to differentiate between users who attempt to disclose confidentials, we propose to insert user's biometric informaion transparently at per-packet basis, and also verify a performance by simulation.

• Journal of Digital Convergence
• /
• v.19 no.10
• /
• pp.287-293
• /
• 2021

Recently, public certificates issued by nationally-recognized certification bodies have been abolished, and internet companies have issued their own common certificates as certification authority. The Electronic Signature Act was amended in a way to assign responsibility to Internet companies. As the use of a joint certificate issued by Internet companies as a certification authority is allowed, it is expected that the fraud damage caused by the theft of public key certificates will increase. We propose an authentication model that can be used in a security gateway that combines PKI with a blockchain with integrity and security. and to evaluate its practicality, we evaluated the security of the authentication model using Sugeno's hierarchical fuzzy integral, an evaluation method that excludes human subjectivity and importance degree using Delphi method by expert group. The blockchain-based joint certificate is expected to be used as a base technology for services that prevent reckless issuance and misuse of public certificates, and secure security and convenience.

• Journal of the Korea Convergence Society
• /
• v.6 no.6
• /
• pp.185-193
• /
• 2015

The wisdom contents consists of an ordinary person's ideas and experience. The Wisdom Market [1] is an online business model where wisdom contents are traded. Thus, the general public could do business activities in the Wisdom Market at ease. As the wisdom contents are themselves the thought of persons, there exists many similar or duplicated contents. Existing copyright protection schemes mainly focus on the primary author's right. Thus, it's not appropriate for protecting the contents of Collective Intelligence that requires to protect the rights of collaborators. There should exist a new method to be dynamic capable of combining and deleting rights of select collaborators. In this study, we propose collective copyright authentication scheme suitable for the contents of Collective Intelligence. The proposed scheme consists of collective copyright registration, addition and verification protocols. It could be applied to various business models that require to combine multiple rights of similar contents or to represent multiple authorships on the same contents.