当组播规模很大时，更新组密钥的效率是一个重要的问题。
When the size of the multicast is large, the efficiency of rekeying is a very important problem.
为达到完美向前和完美向后保密以及对付密码分析，需要更新组会话密钥。
In order to achieve perfect forward and perfect backward secrecy, and to counteract cryptoanalysis, the group session keys should be rekeyed.
默认情况下，不会更新组；如果指定GROUP_UPDATE，则需要更新组，使之完全与新名称匹配。
By default, the group is not updated in this case; if you specify GROUP_UPDATE, the group is updated to exactly match the new name.
应用推荐