Some embodiments of the present invention comprise a method, system, and/or computer program product for a publish/subscribe messaging system. A processor identifies a subscriber of a pub/sub messaging system. The processor retrieves a stored encrypted key for the identified subscriber of the pub/sub messaging system. The processor communicates the retrieved encrypted key to a user selected from a group comprising a publisher of the pub/sub messaging system and the identified subscriber of the pub/sub messaging system. The processor implements end-to-end encryption of messages of the pub/sub messaging system based on key-groups.