Provided is a method and apparatus for configuring keys of groups contained in a domain. The method includes generating a common key and N distribution keys according to the number (N) of users who join a domain, transmitting the common key to users' devices, and transmitting N−1 distribution keys of N different distributions keys to the users' devices, wherein a set of the N−1 distribution keys received by the user's device is different from a set of the N−1 distribution keys received by devices of other users who join the domain.