dApps: Public networks & Messaging

Question

Could you please help me to figure out the following questions?

1. Is it safe if users of a decentralized application use public nodes endpoint via RPC to make transactions to smart contracts? Such as https://validate.eosnation.io/eos/reports/api_versions.html or node what exposed to the world by someone else. Is it possible that this public network may work as Man-In-The-Middle to steal data? Or if I ask users of my application to setup their public nodes, can I trust them?
2. Is there a way to implement text messaging in fully decentralized dApp? WebRTC not the case because I need to store sent messages somewhere and STUN / TURN servers may be single points of failure.

Thanks!

Answer 1

It's probably better to ask 1 qusetion per topic instead having 2 unrelated topics together.

1. Public RPC API nodes cannot modify any transactions since they are signed by the key of the person initiating the transaction. The API could drop the transaction, however. You can submit the same transaction to multiple API endpoints to mitigate this.