In Digital TV service, subscribers get the access of channels of their interest. In conditional access systems (CAS), Control Word is used to deliver the multimedia content to legitimate subscribers securely. In order to update the Control Word frequently, a large number of messages are exchanged in the conventional key distribution systems. This article analyzes the strengths and weaknesses of the existing key distribution protocols for CAS and presents an efficient key distribution protocol for CAS based on Elliptic Curve Cryptography. The proposed protocol minimizes the storage cost and communication cost of subscribers. In addition to this, the proposed protocol facilitates the unrestricted channel package composition and minimum communication cost on rekeying. The proposed protocol also provides perfect forward and backward secrecy. As a result, the proposed protocol is well suited for Pay-TV systems.

中文翻译：

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条件接收系统的高效且安全的密钥管理

在数字电视服务中，订户可以访问他们感兴趣的频道。在条件接收系统 (CAS) 中，控制字用于将多媒体内容安全地传送给合法用户。为了频繁地更新控制字，在传统的密钥分发系统中交换了大量消息。本文分析了现有CAS密钥分发协议的优缺点，提出了一种基于椭圆曲线密码学的高效CAS密钥分发协议。提议的协议最大限度地减少了订阅者的存储成本和通信成本。除此之外，提议的协议促进了不受限制的通道包组合和重新加密时的最小通信成本。提议的协议还提供完美的前向和后向保密。