Combination-based broadcast encryption method

摘要

A combination-based broadcast encryption method includes: assigning by a server a base group of different combinations to each user; producing and sending secret information for each user by using as a base the base group allocated to each user; producing and sending an inverse-base parameter value through calculations with integers used to produce the base group and key value information of one or more privileged users; and deriving a group key by using the key value information of the privileged users, encrypting a session key by using the derived group key, and sending the encrypted session key to each user. Accordingly, each user is assigned a different base through a combination, thereby having security against collusion attacks.

主权项

1. A broadcast encryption method comprising:
generating, by a server, a base group through combinations of integers out of a plurality of different integers having values greater than 1, and assigning the base group of different combinations to each user of a plurality of users; generating secret information for each user through calculations with key value information allocated to a corresponding user by using the base group allocated to each user as a base, and sending the secret information to each user; generating an inverse-base parameter value through calculations with an integer used to produce the base group and key value information of at least one privileged user, and sending the produced inverse-base parameter value to each user, in order for only the at least one privileged user of the plurality of users to eliminate the base group from the secret information; and deriving a group key based on the key value information of the privileged users, encrypting a session key with the derived group key and sending the encrypted session key to each user.