As we attempt to implement a cryptocurrency wallet that will function optionally without direct internet access, there are quite a few challenges. We need to safely escrow currency to be traded as well as safely create transactions without confirmation from the network.
The wallet will likely be nrf52840 based, though we will research any recent chips as well. This will allow for NFC and Bluetooth based transfers and updates. The USB device capability should help for updates as well. There are internal cryptography features on the chip, but we may try to use additional hardware to help prevent double spend hacks.
We will try to make it solar powered and yet cheap to make/distribute.
Our initial experiment will be on the Ethereum network. We propose to implement escrow contracts that hold the wallet currencies on network waiting for valid signed requests to authorize withdrawals. We may need to require both wallets to check in to the network before a transaction is confirmed, but hopefully we can simplify that.