What is Key selection vector?

A Key Selection Vector is a numerical identifier associated with a Device Key Set which is distributed by a Licensor or its designee to Adopters and is used to support authentication of Licensed Products and Revocation as part of the HDCP copy protection system. The KSV is used to generate confidential keys, specifically used in the Restricted Authentication process of HDCP. Restricted Authentication is an AKE method for devices with limited computing resources. This method is used by copying devices of any kind and devices communicating with them for authenticating protected content. The restricted authentication protocol uses asymmetric key management and common key cryptography, and relies on the use of shared secrets and hash functions to respond to a random challenge.