I'm considering building a Lightning Network vending machine that is offline but has the capability to create LN invoices and verify payments.
As an example the scheme has:
- One offline vending machine.
- One online node to validate payments.
- One user (online with a cellphone).
For that there must be:
- A way for the vending machine to provide valid invoices that can be paid to the online node.
- A way for the user to communicate a prof-of-payment to the vending machine.
Is this currently viable? Is this something that can/should be standardized so every wallet can implement it?