A Dual Channel Technique for Content Protection in IPTV

Transcription

1 International Journal of Electronics and Computer Science Engineering 370 Available Online at ISSN A Dual Channel Technique for Content Protection in IPTV Ashish Kumar 1 Jaishree Tanwar 2 Chandresh Bakliwal 3 Arya Institute of Engineering and Technology, Kukas, Jaipur. #1 aishshub@gmail.com #2 jaishreetanwar86@gmail.com #3 chandresh.2410@gmail.com Abstract- With the introduction of IPTV (Internet Protocol Television), traditional wireline content providers and service providers are entering a new era of delivering broadcast and Video on demand(vod) services to their customers. The Content Protection has becoming an extremely important issue as the use of IPTV services are increasing over the Internet. In this paper, we are proposing a new method for improving the performances of the settop box (STB) for video on demand(vod) feature for IPTV. Here we are replacing the traditional complete encryption, partial encryption and selective encryption by a dual channel based encryption scheme, which can resist the content leakage or avoid illegal copying and playing of video. Keywords:IPTV, VOD, Content Protection, STB, Dual channel encryption scheme. I. INTRODUCTION IPTV) is a system that delivers digital television services over the internet by using Internet Protocol suite[1]. The video channels and programs are delivered to the television sets through a broadband connection, instead of being delivered through conventional terrestrial, satellite signal, and cable television formats. The video streams are encoded as a series of IP packets and then carried out by the public internet means which can be received by customer by having a set-top box and service subscription. IPTV services are classified into three main groups i.e., time-shifted television, live television and video on demand (VOD). The time-shifted television that replays a TV show that was broadcast hours or days ago. Live television uses Internet Group Management Protocol (IGMP) [2] to connect to a multicast stream, with or without interactivity related to the current TV show; while video on demand (VOD) uses the Real Time Streaming Protocol (RTSP) to browse a catalog of videos, not related to TV programming and to transmit media stream. IPTV can be bundled with other internet protocol services, including VoIP and high-speed Internet access which is referred as Triple Play service. So the services provided by IPTV is a complete package that allows customers to watch TV, browser the internet and making a long distance calls using the VoIP. In order to receive the IPTV signals a computer or a television set with a set-top box is required[2]. In IPTV related services, such as cable TV, terrestrial TV and VOD, content security is an important issue. Generally, there are 2 main types of technological solutions to current Content Protection in IPTV systems. The one is IP CAS(IP Conditional Access System), which is similar to the conventional Conditional Access (CA) system applied in digital television (DTV). The other one is IP DRM, whose solutions are often intended to be cross-platform to work on PCs, PDAs and mobile phones as well.[3] Generally, Conditional Access (CA) technique [4][5][6] which is similar to IP CAS, is used to control the TV program view. It is implemented by Set- top box which decrypts the program that is encrypted at the head-end. Two kinds of CA systems have been reported till now, i.e., smartcard based system and PC-card based system. The former one is widely used in TV set that is popular in families. The Digital Rights Management (DRM) systems [7][8] are proposed to protect multimedia services from illegal users, but they not capable in solving the problems in IPTV. Park et al. [9] proposed the content

2 IJECSE, Volume2, Number 1 Ashish Kumar et al. 371 distribution system based on MPEG-4 ISMACryp protocol in IP set-top box environments, which implements the secure DRM client in set-top box. Wang et al. [10] invented a software for IPTV STB, which makes IPSTB able to protect itself from failure updating. Lin and Chen [11] proposed a method to control the Set-Top Box by mobile devices. Shiguo Lian[12] proposed the lightweight packet encryption instead of traditional complete encryption in order to reduce the time cost. This paper is arranged as follows. In Section 2, basic IPTV architecture and functional block IP STB are dicussed. In Section 3, the works related to STB, media encryption are introduced. The proposed scheme is presented in Section 4. Finally, in Section 5, conclusions are drawn and future work is presented. II. IPTV Architecture A. General view A sample IPTV system is shown in figure 1. This diagram depicts the IPTV system gathering content from various sources including stored media, network feeds, live studio sources and communication links. Figure.1: Basic IPTV Architecture The head end of IPTV(where the TV program is encrypted) is converting the media sources into a new form, which is easier to be managed and distributed. The content management system is designed to manage media at scheduled times i.e. to store, move and send out the media.the users who are connected to the IPTV system get multiple channels simultaneously by distribution system. The user can view IPTV programs on analog televisions converted by an adapter box known as IP set top box, on a computer or on IP televisions[13]. B.Viewing devices (STB) The functional block diagram of an IP STB is shown in figure 2. This diagram shows that the IP packets that are encapsulated in Ethernet packets are received by IP STB. Then the IP STB extracts the IP packets and obtain the transport stream. For detection and correction of errors, channel decoder is used which provides the transport stream to descrambler. The key information is received by descrambler assembly either from a smart card or from an external conditional access system.

3 A Dual Channel Technique for Content Protection in IPTV 372 Figure.2: Architecture of a generic IPTV Set-Top Box By using the keys, the IP STB can easily decode the transport stream and the specific program stream which is encapsulated in the IP packet, is extracted by the program selector that the user has selected. Then to obtain the program information, the IP STB then demultiplexes the transport stream. The program table let the IP STB to know which streams are for audio, video and any other media for that specific program. Finally, the program stream is divided into its elementary streams (audio, video and control) which is then supplied to a compositor that creates the video signal that will be displayed by the television[13]. III. RELATED WORK A. Set-Top Box Importance in IPTV The set-top box in IPTV realizes the receiving and conversion of the TV program or content [9][10], as shown in figure.3. We have discussed that the STB decodes the IP data packets and decompress the TV contents. Simultaneously some CA related operations are also performed by STB, including content decryption, key authentication, key decryption, etc for security. We will focus only on the operations on the TV content, taking the scheme of content distribution in [9]. Figure.3: Set-Top Box In IPTV

4 IJECSE, Volume2, Number 1 Ashish Kumar et al. 373 At IPTV head-end, the TV contents are compressed with MPEG-4, then encrypted using ISMACryp, and at last, encoded with streaming protocols. The TV streaming in STB, is firstly decoded using streaming protocols, then decrypted using ISMACryp, and lastly, decompressed with MPEG-4. In the existing IPTV scheme, there exists challenging problem, i.e., content leakage between the IPTV sever and STB. Thus, the content can be accessed by the unauthorized or illegal customers. B. Multimedia Encryption One of the key techniques in CA or DRM systems is Multimedia encryption, which convert multimedia content into an unintelligible form under the control of the key. The method encrypts the compressed media content with traditional cipher directly and completely [9][14]. This method is known as complete encryption, having high computing complexity as it encrypts the whole data stream. Alternative method, i.e. partial encryption [15] is proposed to reduce the encrypted data volumes. This kind of method for encryption selects sensitive parameters from media data, that depends on the multimedia data format. Another method, called as compression-combined encryption [16], combines encryption with compression and keep file format unchanged. IV. PROPOSED DUAL CHANNEL SCHEME A clear need for a security mechanism is required which can act between the video on demand server and the customer set top box. Both should run a secure protocol which not only encrypt the video data but also avoid illegal copying and playing. Here we propose a novel technique for encryption of videos demanded by digital TV subscribers. As the name suggests the scheme converts the original video into dual channel data. Each of the channel does not have complete information about the original video. The video data is divided into two files which have the video frames to be played in a scrambled sequence. This dual channel division is unique for every video and for every subscriber. So to access the video only a genuine subscriber is authenticated. All the secret keys required to generate and scramble the dual channel frames are seeded over the subscriber id. The proposed architecture for video on demand feature for IPTV comprises of several modules. These modules interact with each other at different levels to generate a better and secure strategy. The vaious modules are VOD server, Encoding server, transmission channel and set top box (STB). Each of them serve a particular purpose for the system. Several permanent and temporary storages are also used. Permanent storage is at VOD server where all the videos are kept. These are properly indexed for efficient searching. V.CONCLUSIONS AND FUTURE WORK This paper proposed a dual channel scheme to improve the existing set-top box based secure multimedia distribution schemes. That will restrict the unauthorized or illegal access of the digital TV content as well as the various services offered by IPTV. To implement this scheme in various platforms is our future work. References [1] ITU-T IPTV Focus Group (FG IPTV). [2] Engineers Garage inspiring Creations. page=2 [3] ZHANG Hua, CHEN Chunxiao, ZHAO Li, YANG Shiqiang, ZHOU Lizhu, Content Protection for IPTV-current state of the art and challenges, IMACS Multiconference on "Computational Engineering in Systems applications "(CESA), October 4-6, 2006, Beijing,

5 374 A Dual Channel Technique for Content Protection in IPTV China. [4] T. Jiang, Y. Hou and S. Zheng, "Secure Communication between Settop Box and Smart Card in DTV Broadcasting," IEEE Transactions on Consumer Electronics, Vol. 50, No. 3, AUGUST 2004, pp [5] F. Tu, et al., "On key distribution management for conditional access system on Pay-TV system," IEEE Trans. on Consumer Electronics, Vol.45. Feb 1999, pp [6] T. Jiang et al., "Key distribution based on hierarchical access control for Conditional Access System in DTV broadcast," IEEE Trans. On Consumer Electronics, Vol. 50. Feb 2004, pp [7] Open Mobile Alliance (OMA). [8] Internet Streaming Media Alliance (ISMA). [9] S. Park, J. Jeong, and T. Kwon, "Contents Distribution System Based on MPEG-4 ISMACryp in IP Set-top Box Environments," IEEE Transactions on Consumer Electronics, Vol. 52, No. 2, MAY [10] Q. Wang, Q. Du, G. Lin, "IPTV STB Software Update Scheme Based on SNMP," 2006 IEEE International Conference on Electro/information Technology, May 2006, page(s): [11] C.-C. Lin and M.-S. Chen, "On Controlling Digital TV Set-Top-Box by Mobile Devices via IP Network," Proceedings of the Seventh IEEE International Symposium on Multimedia (ISM 05), [12] Shiguo Lian, Member, IEEE, Zhongxuan Liu, Member, IEEE, Secure Media Content Distribution Based on the Improved Set-Top Box in IPTV, IEEE Transactions on Consumer Electronics, Vol. 54, No. 2, MAY 2008 [13] Radu ARSINTE, an experimental architecture for basic iptv concepts implementation and testing, acta technica napocensis Volume 49, Number 4, [14] R. A. Mollin. An Introduction to Cryptography, 2nd edition. CRC Press,2006. [15] S. Lian, Z. Liu, Z. Ren, H. Wang, "Secure Advanced Video Coding Based on Selective Encryption Algorithms," IEEE Transactions on Consumer Electronics, Vol. 52, No. 2, pp , May [16] B. Furht, D. Kirovski. Multimedia encryption and authentication techniques and applications. Boca Raton, Fla.: Auerbach Publications, 2006.