Method for reencrypting the cipher key of HDCP

A method of key encrypting is encrypting data which is encrypted, it includes encrypting steps: processing unit reads key data, and encrypts the key; and storing step: after the encrypting, data encrypted is stored in memory unit by writing unit. The deciphering is picking up the encrypted key to control unit via transmission bus, encrypting the encrypted key. The key encrypting can avoid problems that key is easy to fetch and embezzle because plants of multiple terminal products use the same method of key encrypting; the safety factor of key is increased greatly.