Let's say that I want to build a Dapp such that users can exchange messages between each other. I guess you can consider it a chat Dapp. Is there any way for the two users to find the "address" of each other on the blockchain and then start communicating without using any transaction or gas?
1 Answer
Theoretically, that's exactly the usecase for whisper.
For an example with addressing/encrypting via public key, see Looking for a working Whisper example
Practically, I am not sure how performant whisper is in it's current state. Not all nodes have whisper enabled. I am also not sure why nodes should spend resources on relying whisper messages. There is no direct benefit to them.