Abstract: Protection against unauthorized access to stored content on a video appliance such as a set-top box/PVR (Personal Video Recorder) is provided by encrypting stored content using an event key derived by hashing a base key unique to the set-top box/PVR with event-specific information unique to the stored content. A content handle derived from the event-specific information (and optionally identical thereto) is stored along with the encrypted stored content, identifying it. To decrypt an item of stored content, the event key is recreated by once again hashing the base key (securely stored within the set-top box) with the event-specific information associated with the item of stored content (re-derived from the content handle, as necessary). This event key, identical to the event key used to encrypt the stored content, is then used to decrypt it, making it available for playback. Unauthorized access to deleted content is prevented by erasing (e.g.

Abstract: In a video on demand (VOD) system, methods and apparatus are provided for seamlessly switching back and forth between two pre-encrypted files having changing encryption keys. Such switching back and forth may be required when a VOD server stores both a “normal” copy of a movie and a “special” copy such as a “trick-play” version for, e.g., fast forward and rewind effects. Instead of using keys with changing parities in both streams, the special stream is encrypted with keys using the same parity (even or odd), while the normal stream is encrypted with one dynamic key (odd or even) and one fixed key (even or odd). Other special streams, such as scene branch streams and alternate angle streams can also be accommodated.

Abstract: The present invention relates to methods and apparatus for simultaneously decrypting multiple services received on separate encrypted multiplexed transport streams. A plurality of encrypted multiplexed transport streams may be received at a television terminal. Each transport stream may have at least one service. The plurality of multiplexed transport streams may be received by, for example, multiple tuning devices and/or provided from a storage device, such as a Personal Versatile Recorder (PVR). A plurality of desired services are selected from a subset of the transport streams. The desired services are multiplexed into a desired service multiplex and decrypted by a single decryption engine to provide a desired decrypted multiplex. The desired decrypted multiplex is then demultiplexed so that the desired services can be decoded and provided to a user.

Abstract: An enlargement feature of a graphical user interface (GUI) is disclosed. When a portion of a digital image displayed in the GUI is selected for enlargement, an enlarged version of the selected portion is displayed adjacent to the remaining portion of the original image that was not selected for enlargement. The digital image may include a plurality of image portions (e.g., individual display windows) selectable for enlargement, such as those found in a CATV electronic programming guide (EPG). In one embodiment, hidden supplemental data corresponding to the selected portion is only revealed in the enlarged version of the selected portion, so that it can be more easily viewed. In another embodiment, an enlargement feature application program is downloaded to a local device that controls the GUI, in response to a subscriber accepting an offer presented by a service provider.

Abstract: A local device associated with a communication network is tested for signs of tampering by downloading from a remote device, via the network, a policing code object into the local device. The policing code object is executed within the local device and a message including the results of tests performed by the policing code object are evaluated to determine whether corrective action is required.

Abstract: The present invention provides methods and apparatus for creating a Program Association Table (PAT) for a reduced portion of a multiplexed data stream, when the multiplexed data stream has been reduced, for example, to carry fewer services over a cable television plant. More particularly, the present invention provides methods and apparatus for creating a PAT for a desired combination of multiplexed data stream subgroups contained within an incoming data stream, when the incoming multiplexed data stream is reduced. The invention enables a new PAT to be output which correctly corresponds to the services in a reduced data stream (e.g., for cable-side transmissions). The present invention is particularly useful when reducing high data rate satellite television data streams for cable-side transmission.

Abstract: The present invention relates to a method and apparatus for detecting a high definition television signal (e.g., a high definition MPEG2 data stream) and re-encoding the high definition signal to create a standard definition television signal. In particular, the invention involves re-encoding a copy of the high definition (HD) signal into a standard definition (SD) signal and combining both the original signal and the re-encoded standard definition signal into a multiplexed signal. The provision of both an SD signal and an HD signal in the multiplexed signal enables both SD television receivers and HD television receivers to receive content initially provided as an HD signal. The re-encoding may be performed, for example, at a cable television system headend. The HD television signal may contain one or more television services (channels). The invention enables backward compatibility between an HD data stream and SD receivers.

Abstract: A method and apparatus are provided for controlling access to digital signals sent via a first communication path and retransmitted over a second communication path. The digital signals, having been encrypted by a first encryption scheme and sent over the first communication path, are received and decrypted. The decrypted signals are then retransmitted over the second communication path using a second encryption scheme that differs from the first encryption scheme.