In a typical distribution system of signals in a content delivery network, such as for cable or satellite television, there are various components that reside on a single physical system or on separate systems linked by one or more communication networks. Such content delivery networks may include content providers which provide content delivered across the network, such as audio, video, data, applications, or combinations thereof.
In a content delivery network, the content is typically provided by content providers into the content delivery network as one or more signals. Such signals are typically encoded to prevent unauthorized access and use of the signal. Receivers, such as digital television receiver units, receive from the network and use such encoded signals for use by users. A receiver typically includes a decode function so that receivers may make use of the encoded signals it receives from the content delivery network. A content delivery network also typically includes a conditional access system connected to the network, which controls the content that any particular receiver may access and use. The conditional access system typically operates in conjunction with the receivers to control the content that any one receiver may access and use. A receiver typically perform checks with the conditional access system to determine the particular content that it is permitted to receive and use, and then decode only such authorized content.
Additional background details regarding content delivery networks, conditional access systems, and technologies deployed therein are described in the following United States patents, the disclosure of which are hereby incorporated by reference:    U.S. Pat. No. 4,461,032 to Skerlos    U.S. Pat. No. 4,510,623 to Bonneau et al.    U.S. Pat. No. 5,146,496 to Westerfer et al.    U.S. Pat. No. 5,224,161 to Daniel et al.    U.S. Pat. No. 5,880,769 to Nemirofsky et al.    U.S. Pat. No. 5,970,206 to Yuen et al.    U.S. Pat. No. 6,067,440 to Diefes    U.S. Pat. No. 5,485,518 to Hunter et al.    U.S. Pat. No. 5,828,402 to Collings    U.S. Pat. No. 5,438,620 to Ryan et al.
Some conditional access systems known in the art have been compromised in a manner that allows for unauthorized usage of content signals. Methods of compromising these systems include deliberate or accidental operational errors, exploitation of design or operational flaws in the systems, and “hacking” or reverse-engineering of the systems.
Detection of unauthorized access and usage may often be rendered difficult, as a compromised receiver may not have a method of communicating back with the conditional access system, or the return communication means may be disabled on the compromised receiver.
Correction of conditional access problems may also be a lengthy process, with compromised (also known as “pirated”) systems sometimes remaining in operation for several years, with a succession of counter-measures and counter-counter-measures being deployed respectively by the content delivery network operators and hackers.
There is a need for a system and method for providing conditional access to a content delivery network wherein unauthorized usage of signals by a receiver may be detected, and having such a receiver optionally disabled.