[Feature Request]: Generate node ID out of public key

[contra-bit]

Platform

Cross-Platform

Description

I'd like to propose creating the node ID (aka node number) out of the public key,
similar to how software like Tor and SSH handle it. This would allow users to
choose whether a factory reset node should appear as new or retain its old
identity.

Currently, the node ID is generated from the MAC address, which leads to
issues when a node is reset and a new public and private key pair is
generated without warning. This causes PKI mismatches and prevents
functions like updating the position or getting a new node name.

By generating the node ID from the public key, users can choose to back up
their private and public keys and restore them after a factory reset,
allowing the device to retain its identity on the network. If the keys are
not restored, the device will appear as a new node.

This approach also solves a a privacy concern, as it allows users to appear
as a new device on the network if they choose to.

It's essential to inform users about the importance of backing up their keys,
as mentioned in Feature Request #272. This should be done in a secure and
user-friendly way, such as prompting the user to download or print a copy of
their private keys.

Regarding the open points in Feature Request #272 Prepare for PKI & Config Updates:

Display message when others in conversation change their key.

Tying the node ID the public key, will minimize the risk of a user resetting their node.
The chance of a user accidentally messing up their public key is minimized.

Allow user to forget node, allowing it to rejoin with new key

This can be implemented by adding an option to
"forget" a node, which would remove the node's public key and any
associated data such as the node id from the local device.
Rejoining the network, with a different public key and the same node id, will not be possible.
This will be the same as deleting a node. If the user wants to keep the node, he will restore his keys.

Here's a possible implementation:

• When generating a new node ID, use a hash of the public key instead of the MAC
  address.
• Provide an option for users to choose whether a factory reset node should
  retain its old identity or appear as new. (This would create a backup of the private and public keys and update the node, after the factory reset).
• Document the process of adding multiple remote management keys and the
  implications of adding only the key of a remote device.
• Implement notifications for key changes in conversations.
• Implement the "forget node" option.

This feature would improve the overall security, privacy, and user experience
of the Meshtastic network. It addresses the issues mentioned in Feature
Request #272 Prepare for PKI & Config Updates and #281 Prompt User to download PKI keys for backups, and provides a more robust and user-friendly PKI
system.

Relevant issues

• #281 Prompt User to download PKI keys for backups
• #272 Prepare for PKI & Config Updates
• #315 Add ability to add all 3 PKI admin keys
• Key Exchange not mentioned yet
• Meta PKI Issue
• Dicussion on the meaning of Node ID
• Relevant for how to implement the Node ID generation