Multicast security agent assembly and multicast encryption management method

The invention relates to a multicast security agent assembly and a multicast encryption management method. File encryption and decryption submodules in a multicast module serve as specific execution modules for multicast users to encrypt/decrypt messages or files, an RSA (Rivest-Shamir-Adleman) algorithm is adopted as a multicast encryption/decryption algorithm, and private keys of the users are taken as decryption keys. After system authentication, if some users in an intranet need intra-group communication, a group key formed by a product of the private keys of all the members can ensure multicast security; and when new users participate in the intranet or the old users exit the intranet, the new users can not access communication contents before accessing and the exited users can not access the communication contents after exiting through updating the group key, therefore, the functions of encryption with one key and decryption with multiple keys in a multicast group are realized. When group members change