• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.1
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• pp.80-86
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• 2010

This paper describes the development result of S-band Transmitter of STSAT-3 by satellite research center(SaTReC), KAIST. STSAT-3 has two kinds of communication channels, S- band for Telemetry & Command and X-band for mission payload. S-band Transmiiter(STX) consist of modulator, frequency synthesizer, power amp and DC/DC converter. The modulation scheme of STX is FSK(Frequency Shift Keying). The interface between spacecraft OBC and STX is RS-422. The STX is based on modular design. The RF output power of STX is 1.5W(31.7dBm) and BER of STX is under 1E-5. The Test of STX is completed successfully such as functional Test and environmental(vibration, thermal vacuum) Test.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.1
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• pp.109-116
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• 2018

This paper describes an area-efficient design of SHA-256 hash function that is widely used in various security protocols including digital signature, authentication code, key generation. The SHA-256 hash processor includes a padder block for padding and parsing input message, so that it can operate without software for preprocessing. Round function was designed with a 16-bit data-path that processed 64 round computations in 128 clock cycles, resulting in an optimized area per throughput (APT) performance as well as small area implementation. The SHA-256 hash processor was verified by FPGA implementation using Virtex5 device, and it was estimated that the throughput was 337 Mbps at maximum clock frequency of 116 MHz. The synthesis for ASIC implementation using a $0.18-{\mu}m$ CMOS cell library shows that it has 13,251 gate equivalents (GEs) and it can operate up to 200 MHz clock frequency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.7C
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• pp.696-705
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• 2005

The rapid progress of the software has enabled individuals to copy and remake digital contents, which was only done by professionals. However, this rapid growth of software has brought many other defects. As a solution to the problems, contents producer needs to have certification and inspection of its contents text and hold the proprietary rights. In this paper, the new video watermarking scheme is proposed which is appropriate for the requirements mentioned for digital video contents and it is applied to MPEG-2 video encoder and decoder. In order to insert watermark sequence for digital video data, watermarking used blocks reordering algorithm and SCL(secret code list). It is satisfied two properties of cryptography that confidentiality and integrity. We test the proposed algorithm to see its performance in terms of watermark capacity, compression robustness and visual quality impact. According to the experiment of proposed watermarking algorithm, we obtained satisfactory results that watermark can still be extracted after MPEG-2 re-encoding at lower bit rates. It is important property for data hiding and user authentication in video data.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.1
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• pp.11-18
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• 2003

As the Internet moves to mobile environment, one of the most serious problems for the security is to required a new security Protocol with safety and efficiency. To solve the problem. we Propose a new Protocol that reduces the communication franc and solves the problem associated with the private security keys supplied by the trusted third party. The protocol is a non-Interactive oblivious transfer protocol, based on the EIGamal public-key algorithm. Due to its Non-Interactive oblivious transfer protocol, it can effectively reduce communication traffic in server-client environment. And it is also possible to increase the efficiency of protocol through the mechanism that authentication probability becomes lower utilizing a challenge selection bit. The protocol complexity becomes higher because it utilizes double exponentiation. This means that the protocol is difficult rather than the existing discrete logarithm or factorization in prime factors. Therefore this can raise the stability of protocol.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.5
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• pp.59-71
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• 2005

A RFID (Radio Frequency Identification) system receives attention as the technology which can realize the ubiquitous computing environment. However, the feature of the RFID tags may bring about new threats to the security and privacy of individuals. Recently, Juels proposed the minimalist cryptography for very low-cost RFID tags, which is secure. but only under the impractical assumption such that an adversary is allowed to eavesdrop only the pre-defined number of sessions. In this paper, we propose a scheme to protect privacy for very low-cost RFID systems. The proposed protocol uses only bit-wise operations without my costly cryptographic function such as hashing, encryption which is secure which is secure against an adversary who is allowed to eavesdrop transmitted message in every session any impractical assumption. The proposed scheme also is more efficient since our scheme requires less datas as well as few number of computations than Juels's scheme.

• Journal of Industrial Convergence
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• v.18 no.6
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• pp.147-154
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• 2020

It is difficult to educate the overall operation of public and private blockchains with different characteristics. Recently, most education for blockchain is targeted at public blockchains such as Bitcoin and Ethereum. However, in an actual business environment, a private blockchain such as HyperLedger Fabric is used because access to corporate data is controlled through user authentication. In the case of HLF-based education, it is necessary to understand various components that are not in the public blockchain, such as peers, orderers, and channels. In this paper, a lab framework for HLF is designed for an efficient and systematic understanding of the functions and operations. The framework consists of HLF network, chaincode, and decentralized software control functions. Through the framework, the network configuration, distribution and activation of chaincode, and dApp execution process were checked step by step, and it was very easy to understand the overall flow for blockchain services. In addition, it is expected that a systematic understanding of the overall flow will be possible even in future network expansion.

• The KIPS Transactions:PartB
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• v.15B no.4
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• pp.275-284
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• 2008

With increases in recent security requirements, biometric technology such as fingerprints, faces and iris recognitions have been widely used in many applications including door access control, personal authentication for computers, internet banking, automatic teller machines and border-crossing controls. Finger vein recognition uses the unique patterns of finger veins in order to identify individuals at a high level of accuracy. This paper proposes new device and methods for touchless finger vein recognition. This research presents the following five advantages compared to previous works. First, by using a minimal guiding structure for the finger tip, side and the back of finger, we were able to obtain touchless finger vein images without causing much inconvenience to user. Second, by using a hot mirror, which was slanted at the angle of 45 degrees in front of the camera, we were able to reduce the depth of the capturing device. Consequently, it would be possible to use the device in many applications having size limitations such as mobile phones. Third, we used the holistic texture information of the finger veins based on a LBP (Local Binary Pattern) without needing to extract accurate finger vein regions. By using this method, we were able to reduce the effect of non-uniform illumination including shaded and highly saturated areas. Fourth, we enhanced recognition performance by excluding non-finger vein regions. Fifth, when matching the extracted finger vein code with the enrolled one, by using the bit-shift in both the horizontal and vertical directions, we could reduce the authentic variations caused by the translation and rotation of finger. Experimental results showed that the EER (Equal Error Rate) was 0.07423% and the total processing time was 91.4ms.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.2
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• pp.1-9
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• 2008

As the security requirements of mobile phones have been increasing, there have been extensive researches using one biometric feature (e.g., an iris, a fingerprint, or a face image) for authentication. Due to the limitation of uni-modal biometrics, we propose a method that combines face and iris images in order to improve accuracy in mobile environments. This paper presents four advantages and contributions over previous research. First, in order to capture both face and iris image at fast speed and simultaneously, we use a built-in conventional mega pixel camera in mobile phone, which is revised to capture the NIR (Near-InfraRed) face and iris image. Second, in order to increase the authentication accuracy of face and iris, we propose a score level fusion method based on SVM (Support Vector Machine). Third, to reduce the classification complexities of SVM and intra-variation of face and iris data, we normalize the input face and iris data, respectively. For face, a NIR illuminator and NIR passing filter on camera are used to reduce the illumination variance caused by environmental visible lighting and the consequent saturated region in face by the NIR illuminator is normalized by low processing logarithmic algorithm considering mobile phone. For iris, image transform into polar coordinate and iris code shifting are used for obtaining robust identification accuracy irrespective of image capturing condition. Fourth, to increase the processing speed on mobile phone, we use integer based face and iris authentication algorithms. Experimental results were tested with face and iris images by mega-pixel camera of mobile phone. It showed that the authentication accuracy using SVM was better than those of uni-modal (face or iris), SUM, MAX, NIN and weighted SUM rules.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.1
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• pp.15-21
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• 2010

This paper proposes the multimedia fingerprinting code insertion algorithm when video content is distributed in P2P environment, and designs the collusion codebook SRP(Small RISC Processor) embedded system for the collusion attack prevention. In the implemented system, it is detecting the fingerprinting code inserted in the video content of the client user in which it requests an upload to the web server and in which if it is certified content then transmitted to the streaming server then the implemented system allowed to distribute in P2P network. On the contrary, if it detects the collusion code, than the implemented system blocks to transmit the video content to the streaming server and discontinues to distribute in P2P network. And also it traces the colluders who generate the collusion code and participates in the collusion attack. The collusion code of the averaging attack is generated with 10% of BIBD code v. Based on the generated collusion code, the codebook is designed. As a result, when the insert quantity of the fingerprinting code is 0.15% upper in bitplane 0~3 of the Y(luminance) element of I-frame at the video compression of ASF for a streaming service and MP4 for an offline offer of video content, the correlation coefficient of the inserted original code and the detected code is above 0.15. At the correlation coefficient is above 0.1 then the detection ratio of the collusion code is 38%, and is above 0.2 then the trace ratio of the colluder is 20%.