Method and system for encrypting and decrypting data using an external agent

Abstract

A communication system including a transmitter, a receiver, a communication link (for example, a TMDS-like link), and preferably also an external agent with which the transmitter and receiver can communicate, in which video data (or other data) are encrypted, the encrypted data are transmitted from the transmitter to the receiver, and the transmitted data are decrypted in the receiver, a transmitter and a receiver for use in such a system, a cipher engine for use in such a transmitter or receiver, a method for operating such a transmitter or receiver to encrypt or decrypt data, and a method for distributing keys to the transmitter and receiver. The receiver can be a player coupled to a downstream receiver by a TMDS-like link, and configured to re-encrypt the decrypted data (for example, using an AES or HDCP protocol) and send re-encrypted data over the link to the receiver. Optionally, the player is a repeater which translates the decrypted data from the transmitter, and then re-encrypts the translated data for transmission to the downstream receiver. The transmitter can itself be a player that receives and decrypts encrypted data from an upstream source. In preferred embodiments, the system implements a content protection protocol including a challenge-response procedure. After a new key is supplied to the receiver (and the same new key should have been supplied to the transmitter) and before the receiver can use the new key, the challenge-response procedure requires that the receiver validate the transmitter by verifying that the transmitter has proper knowledge of the new key.

Description

TECHNICAL FIELD OF THE INVENTION [0001] The invention pertains to encryption of data (e.g., data to be transmitted over a TMDS link or other serial link), and to decryption of encrypted data (e.g., encrypted data that has been transmitted over a TMDS link or other serial link). Some embodiments of the invention are methods and systems for content protection using a transmitter that encrypts data, a receiver that receives and decrypts the encrypted data, and an external agent that communicates with at least one of the transmitter and receiver to facilitate the encryption and decryption. BACKGROUND OF THE INVENTION [0002] There are various, well-known serial links for transmitting video data and other data. One conventional serial link is known as a transition minimized differential signaling interface (“TMDS” link). This link is used primarily for high-speed transmission of video data from a set-top box to a television, and also for high-speed transmission of video data from a host p...

AI Technical Summary

Benefits of technology

"The invention is a communication system that uses encryption to securely transmit data over a serial link, such as video or audio data. The system includes a transmitter, a receiver, and a link between them. In some embodiments, an external agent provides keys to the receiver and transmitter, allowing for more keys and changing keys frequently. The external agent can verify the identity of the receiver and transmitter, generate key material, maintain a revocation list, and audit accesses and behaviors to improve security. The receiver can re-encrypt and forward the decrypted data to a downstream device. The system also includes a symmetric content protection protocol with a challenge-response procedure to validate the transmitter's knowledge of a new key."

Problems solved by technology

However, many TMDS-like serial links do not transmit data having blanking intervals, and thus do not encode input data (for transmission) in response to a data enable signal.

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