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The Key Selection Vector means the numeric value associated with a Device Key Set and distributed by Licensor or its designee to Adopters and used to support authentication of Licensed Products and Revocation. It is considered a confidential set of keys used in Restricted Authentication process of the HDCP. Restricted authentication is an AKE method for devices with limited computing resources. This method is used by copying devices of any kind (such as DV recorders or D-VHS recorders) and devices communicating with them for authenticating copy-one-generation and no-more-copies contents. The restricted authentication protocol employs asymmetric key management and common key cryptography and relies on the use of shared secrets and hash functions to respond to a random challenge. ==Role of KSV in Restricted Authentication== This method is based on a device being able to prove that it holds a secret shared with other devices. One device authenticates another by issuing a random challenge that is responded to by modifying it with the shared secrets and multiple hashings. During the authentication process, both parties exchange their KSVs. Then each device adds (without overflow) its own secret keys according to a KSV received from another device. If a particular bit in the vector is set to 1, then the corresponding secret key is used in the addition, otherwise it is ignored. For each set of keys a special key called a KSV (Key Selection Vector) is created. Each KSV has exactly 20 bits set to 0 and 20 bits set to 1. Keys and KSVs are generated in such a way that during this process both devices get the same 56 bit number as a result. That number is later used in the encryption process. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Key selection vector」の詳細全文を読む スポンサード リンク
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