Patent ID: 7231520
Filing Date: 2007-06-12
Classification: G06F,G11B

Abstract:
1. A playback method for decrypting encrypted data read from a recording medium, comprising the steps of: when a player is going to play back the recording medium containing user identification information, intended to identify a user, and data encrypted with the user identification information, causing the player to detect whether a terminal unit with a memory having the user identification information recorded therein along with the data is connected to the player; when it is detected that the terminal unit is connected to the player, exchanging an encryption key between the player and the terminal unit; encrypting the user identification information read from the memory of the terminal unit with the exchanged encryption key and sending it from the terminal unit to the player; judging whether the user identification information sent from the terminal unit is coincident with the user identification information read from the recording medium; and decrypting the encrypted data read from the recording medium when it is judged that the user identification information sent from the terminal unit is coincident with the user identification information read from the recording medium.