Example embodiments provide various techniques for securing communications within a group of entities. In one example method, a request from an entity to join the group is received and a signed, digital certificate associated with the entity is accessed. Here, the signed, digital certificate is signed with a group private key that is associated with a certification authority for the group. The signed, digital certificate is added to a group roster, and this addition is to admit the entity into the group. The group roster with the signed, digital certificate is itself signed with the group private key and distributed to the group, which includes the entity that transmitted the request. Communication to the entity is then encrypted using the signed, digital certificate included in the group roster.