Messages (which exist on top of the Transports layer), contain varying types of information that are needed for the network but, most importantly, everything you see, do, send, or receive, will come and go in the form of messages.
There are 2 essential types of messages in I2P:
- First, the tunnel gateway accumulates a number of I2NP messages and preprocesses them into tunnel messages for delivery.
- Next, that gateway encrypts that preprocessed data, then forwards it to the first hop.
- That peer, and subsequent tunnel participants, unwrap a layer of the encryption, verifying that it isn't a duplicate, then forward it on to the next peer.
- Eventually, the tunnel messages arrive at the endpoint where the I2NP messages originally bundled by the gateway are reassembled and forwarded on as requested.