> Is it sufficient to have a single key shared by all "ends" for the room, or must each user have its own key? It is enough that a single key is shared, that b

> Is it sufficient to have a single key shared by all "ends" for the room, or must each user have its own key? It is enough that a single key is shared, that being said some systems do more because they want to provide additional properties to end-to-end encryption for groups.