[FEAT]: Client notification messages for different public key and failed PKI decryption

[thebentern]

Feature Description

From: meshtastic/protobufs#793

For consideration to improve the UX when PKI fails after a remote node changed their keys (meshtastic/firmware#8211).

The idea is that when we receive a NodeInfo with a different public key than the device has currently stored in its NodeDB, we do not simply ignore it like currently, but we inform the client about this. The client could then either already ask the user if it would like to accept this different key (by importing the same node as Shared Contact with new key), or cache this different public key to be used when the node is receiving a PKI encrypted packet it couldn't decrypt (this is the less "spammy" approach). If it did not yet receive a different public key when the latter happens, it could also ask the user if it wants to clear the currently stored key, such that it is able to accept a new one.

Sub-tasks

• Create Android implementation issue.
• Create iOS implementation issue.
• Create Web implementation issue.

[jamesarich]

How should we handle this Client Notification message in the client applications?

1. We present the user with the option to update the node's contact via a SharedContact w/ new key
2. We cache this different public key to be used when the node is receiving a PKI encrypted packed it couldn't decrypt.

I'm still unclear on how 2 is supposed to work, but 1 makes sense to me as straightforward implementation and interaction.