FIELD: radio engineering, communication.
SUBSTANCE: apparatus comprises: a receiver configured to receive a signed content item and associated security information from a publisher, wherein the security information indicates which group from a plurality of groups is allowed to access the signed content item; a storage unit configured to cache the content item and the associated security information; a processor to implement procedures to enforce security policies defined by the security information; and a transmitter configured to send the signed content item from the cache to a subscriber when the subscriber is a member of a group indicated by the security information as authorised to access the signed content item, wherein the subscriber verifies the signed content.
EFFECT: more secure data transmission within a communication network.
41 cl, 9 dwg
