To provide a security module capable of enabling any content receiving apparatuses connected to a network to receive for looking and listening, of limiting the time of using the content, and of minimizing the damage caused by key leakage.

The security module 60 comprises a confidential information storage means 61 for storing a group signature key unique to a user in an electronic authentication method, and confidential information unique to the user for generating a temporary group signature key which is temporarily generated; a temporary group signature generating means 62 for generating the temporary group signature key which serves as part of authentication information based on the confidential information; and a token generating means 63 for generating a token which serves as part of the authentication information based on a verification key forming a pair with the group signature key, token generating random numbers serving as part of the authentication information, and identification information unique to the user.

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