Patent ID: 7668313

Claim:
A method of protecting an HDCP key set containing 40 56-bit device keys between a message sender and a message recipient having a private encryption key, the method comprising the steps of: randomly generating a session key; and encrypting the session key using a first symmetric-key cipher algorithm with the private encryption key; sending the unencrypted session key and the encrypted session key to the message sender; encrypting the HDCP key set using a second symmetric-key cipher algorithm with the unencrypted session key, wherein each device key within the HDCP device key set is a 56-bit value and is padded with an 8-bit random number prior to DES or Triple DES encryption in order to utilize the entire 64-bit block size of DES or Triple-DES; sending the encrypted private message data and the encrypted session key to the message recipient; decrypting with a processing system the encrypted session key using the first symmetric-key cipher algorithm with the private encryption key by the message recipient; and decrypting with the processing system the HDCP key set using the second symmetric-key cipher algorithm with the decrypted session key.