This extension allows you to link your Bolt Card (or other compatible NXP NTAG device) with a LNbits instance and use it in a more secure way than a static LNURLw. A technology called [Secure Unique NFC](https://mishka-scan.com/blog/secure-unique-nfc) is utilized in this workflow.
**Disclaimer:** ***Use this only if you either know what you are doing or are a reckless lightning pioneer. Only you are responsible for all your sats, cards and other devices. Always backup all your card keys!***
***In order to use this extension you need to be able to setup your own card.*** That means writing a URL template pointing to your LNbits instance, configuring some SUN (SDM) settings and optionally changing the card's keys. There's a [guide](https://www.whitewolftech.com/articles/payment-card/) to set it up with a card reader connected to your computer. It can be done (without setting the keys) with [TagWriter app by NXP](https://play.google.com/store/apps/details?id=com.nxp.nfc.tagwriter) Android app. Last but not least, an OSS android app by name [Boltcard NFC Card Creator](https://github.com/boltcard/bolt-nfc-android-app) is being developed for these purposes. It's available from Google Play [here](https://play.google.com/store/apps/details?id=com.lightningnfcapp).
Up to five 16-byte keys can be stored on the card, numbered from 00 to 04. In the empty state they all should be set to zeros (00000000000000000000000000000000). For this extension only two keys need to be set, but for the security reasons all five keys should be changed from default (empty) state. The keys directly needed by this extension are:
The key #00, K0 (also know as auth key) is used as authentification key. It is not directly needed by this extension, but should be filled in order to write the keys in cooperation with Boltcard NFC Card Creator. In this case also K3 is set to same value as K1 and K4 as K2, so all keys are changed from default values. Keep that in your mind in case you ever need to reset the keys manually.
- Click the QR code button next to a card to view its details. Backup the keys now! They'll be comfortable in your password manager.
- Now you can scan the QR code with the Android app (Create Bolt Card -> SCAN QR CODE).
- Or you can Click the "KEYS / AUTH LINK" button to copy the auth URL to the clipboard. Then paste it into the Android app (Create Bolt Card -> PASTE AUTH URL).
Since v0.1.2 of Boltcard NFC Card Creator it is possible not only reset the keys but also disable the SUN function and do the complete erase so the card can be use again as a static tag (or set as a new Bolt Card, ofc).
This app afaik cannot change the keys. If you cannot change them any other way, leave them empty in the extension dialog and remember you're not secured. Card Auth key (K0) can be omitted anyway. Initical counter can be 0.
