• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.2C
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• pp.200-207
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• 2006

Recently, with the development of information and communication technology, digital pay-TV technology is paid attention. So the Protection of the provided contents is becoming more important. However, in order to encourage an active based on digital TV, the contents and information sent and received respectively by the broadcaster and the subscriber must be protected. Therefore, in this paper, I analyze the requirements to protect the digital contents, the security and efficiency of the previous digital pay-TV system model. Then I proposed a key management model for digital pay-TV system.

• The KIPS Transactions:PartC
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• v.16C no.2
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• pp.199-208
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• 2009

Recently,IP-based broadcasting systems,such as Mobile-TV and IP-TV, have been widely deployed. These systems require a security system to allow only authorized subscribers access to broadcasting services. We analyzed the Conditional Access System, which is a security system used in the IP-based Pay-TV systems. A weakness of the system is that it does not scale well when the system experiences frequent membership changes. In this paper, we propose a group key distribution protocol which overcomes the scalability problem by reducing communication and computation overheads without loss of security strength. Our experimental results show that computation delay of the proposed protocol is smaller than one of the Conditional Access System. This is attributed to the fact that the proposed protocol replaces expensive encryption and decryption with relatively inexpensive arithmetic operations. In addition, the proposed protocol can help to set up a secure channel between a server and a client with the minimum additional overhead.

• Journal of the Korea Society of Computer and Information
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• v.10 no.2 s.34
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• pp.169-177
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• 2005

The Conditional Access System is a complete system for ensuring that broadcasting services be accessible to only those who are entitled to receive them. Secure key management and efficient delivery mechanism are very important design factors to this system. In this paper, we propose secure and efficient protocols which would be well fitted to a Pay TV system including the satellite DMB. Further. by applying our protocol to the existing conditional access system, we propose a new system that properly enables the control of conditional access to the Pay TV in satellite DMB environment.

• Annual Conference of KIPS
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• 2011.04a
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• pp.808-811
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• 2011

Sun 등은 pay-TV 를 위한 새로운 접근제어 모델을 제안하였다. 그들의 모델은 서비스 제공자와 사용자 간의 형평성 (fairness)을 보장하고, 사용자에게 편의 (convenience)를 제공한다. 또한, Sun 등은 그들이 제안한 접근제어 모델을 지원하기 위한 새로운 접근제어 시스템을 제안하였다. 그들이 제안한 시스템은 대규모 그룹에도 적용할 수 있도록 확장 가능한 (scalable) 키 관리를 수행한다. 그러나 그들의 시스템은 pay-TV 의 핵심 보안 요구사항인 후방향 안전성 및 전방향 안전성(backward/forward secrecy)을 만족하지 못할 뿐 아니라, 공모 공격 (collusion attack)에 대한 취약점이 존재하고, 공격에 대한 낮은 복원 능력 (poor reparability)을 갖는다. 본 논문에서는 공격 시나리오를 통해 Sun 등이 제안한 시스템의 보안 문제점을 분석하고 그 결과를 제시한다.

• The Transactions of the Korea Information Processing Society
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• v.4 no.12
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• pp.3123-3132
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• 1997

In this paper, we describe access control system for protection of pay TV program in digital DBS(Direct Broadcast satellite) system. We also propose a possible access control system and operation scenario for scrambling and descrambling which are important in access control system. Transport stream structure and option, entitlement checking message and entitlement management message for access control on digital broadcasting system are described in this paper. Especially, the authentication based on Flat-Shamir and Gulllou-Quisquater schemes required for verification of proper subscriber as access control is oriented to smart card number and subscriber ID(Identity). It has less restriction than scheme oriented to descrambler number.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.1
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• pp.41-55
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• 2005

A group key agreement protocol allows a group of user to share a key which may later be used to achieve certain cryptographic goals. In this paper, we propose a new scalable two-round ID-based group key agreement protocol which would be well fit to a Pay-TV system, additionally. to the fields of internet stock quotes, audio and music deliveries, software updates and the like. Our protocol improves the three round poop key agreement protocol of Nam et al., resulting in upgrading the computational efficiency by using the batch verification technique in pairing-based cryptography. Also our protocol simplifies the key agreement procedures by utilizing ID-based system. We prove the security of our protocol under the Computational Diffie-Hellman assumption and the Bilinear Decisional Diffie-Hellman assumption. Also we analyze its efficiency.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.3
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• pp.67-78
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• 2010

CAS(Conditional Access System) is used in Pay-TV System to prohibit unauthorized user(s) accessing the contents in IPTV broadcasting environment. In the CAS, Smartcard transfers CW which is necessary in the process of descrambling the scrambled program to STB. CW hacking problem is one of the most serious problems in pay-TV system. There have been many researches on generating secure communication channel between smartcard and STB for secure transmitting, But they had problems in efficiency and security. In this paper, we propose a lightweight key agreement protocol based on a symmetric key algorithm. We show that our proposed protocol is more efficient than existing protocols by comparing the amount of computations, and analyzing the security requirement of the proposed protocol.

• Journal of Internet Computing and Services
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• v.10 no.1
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• pp.83-91
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• 2009

The advertisement system on TV is categorized into full duplex TV and Internet Protocol Television (IPTV). For the full duplex TV or the IPTV, channel providers need a number of advertisements and pay enormous expenses for them. Therefore, this study proposes how to reduce unnecessary expenses based on users' preferences. The advertisement system based on users' preferences is designed to decrease unnecessary advertisements with less expense. To identify preferences in usual advertisements and animation advertisements is to reduce expenses due to the necessity of a number of advertisements. The proposed system was designed to provide full duplex advertisements for profits of advertisement industry and considered users' disposition based on preferences of broadcasting advertisements, through which users can have advertisement desired and providers can expect less advertisement expenses and more profits.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.6
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• pp.173-178
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• 2008

With the discontinuation of analog broadcasting in 2012, the cable broadcasters are investing in the conversion to DCATV (Digital Cable TV). DCATV is providing various broadcast of high quality to audiences through paid broadcasting called PPV (Pay Per View). Such services are using various kinds of CASs (Conditional Access System) in order to verify the viewing rights of subscriber. In addition, to respond to the fast changing environment of digital broadcast, not only simple digitalization of broadcast but also services such as PVR (Personal Video Recorder) and VOD (Video On Demand) are provided to subscribers. Because these additional services have many difficult areas to cover with traditional CAS alone, a new plan has become necessary. With the improvement of related regulations in 2008, the test service of IPTV (Internet Protocol TV) which is a broadcast service through the internet started. Because like DCATV, IPTV also sets the real time broadcast and the VOD service as the basic services, the use of appropriate CAS is required. In this study, the CASs for DCATV and IPTV undergo comparative analysis, and the development direction which will benefit both subscribers and broadcasting companies is suggested.

• Journal of Broadcast Engineering
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• v.1 no.1
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• pp.1-6
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• 1996

Digital DBS service using Korea Sat starts at Korea Telecom's Yong-in transmission site. Total 6 transmitting stations are needed. At each transmitting station, 4 TV programs are compressed and multiplexed using MPEG-2, modulated into IF, RF signals, then finally transmitted through antenna. At DBS transponder, received signal is down converted, amplified and re-transmitted to earth. At receiver, signal is received by 45cm dish antenna, then wanted program is selected, demultiplexed and decoded. Transmission performance of BER lOE-ll is implemented by using FEe coding and QPSK modulation. For pay TV management, conditional access system, smart card and modem are used.