UNIV SOUTH CHINA TECHTANG SHAOHUALIANG YUJUNDING JINTA
Provided is a method for managing a hierarchical-group key based on linear geometry, which includes the following steps: step 1, a central controller selects a finite field F, a mapping f and a constant N which are used by a group, and selects an N-dimension private vector for each sub-group; step 2, the central controller selects a mapping parameter r, and maps the private vectors into a set of new vectors in vector space; step 3, the central controller selects a sub-group key for each sub-group, constructs n linear equations sets, and then solves the linear equations sets to obtain results, i.e. public vectors, and n sets of public vectors compose a public matrix; the central controller transmits the public matrix and the mapping parameter r to all sub-group controllers through public channel broadcast or multicast; step 4, the sub-group controllers work out their own secret vectors, and then obtain a set of key vectors by using the secret vectors and the public matrix to perform a linear transform. The present invention displays the advantages of simplicity and flexibility, while effectively avoiding violent attacks.
This invention publishes a secure group key management approach based upon N-dimensional hypersphere. After initialization, the GC admits the new members and assigns identifiers to them when there are new members joining the group, and deletes the leaving members'' private information when there are members leaving the group. If a lot of members join and other members leave the group at the same time, the GC deletes the leaving members'' private information, admits the new members, assigns indemnifiers to the new members, and then chooses mapping parameters, mapping each member''s and its private information to the points in a multi-dimensional space. The GC calculates the central point of the hypersphere, and publishes the central point, the mapping parameter and the identifiers of leaving members if there are members leave. The group members calculate the mapping points, and then calculate the group keys. The invention can effectively reduce user storage, user computation, and amount of update information while re-keying. The independence of the group keys can be kept.
A group key management method based on an n-dimensional sphere is provided. After initialization, when new users join, the group manager accepts and numbers the new users; when users leave, the group manager deletes the confidential information of the leaving users. If there are users joining and leaving at the same time, the group manager deletes the confidential information of the leaving users, accepts the new users joining, numbers the new users and accepts the confidential information of the new users. The group manager then selects the mapping parameters, and snaps the confidential information of each user in the group and of itself to their respective points in space; the sphere center composed by these points is computed, the center and the mapping parameters are published, and the numbers of any leaving users are published. The users in the group compute the corresponding points in space according to their own numbers, and then determine the group key. The present invention can efficiently decrease stored user information, the amount of calculations and messages when the key is updated, and keep the keys independent of each other.