Create or update a Boltcard – for bigger amounts
Write a paylink to generate simple Voucher- or Tippingcards
Voucher cards in a batch – as give-away for an event or a conference
Voucher are represented by a static link (LNURLw) and should only be used for low risc use cases in a limited timeframe since they can be replayed by whoever has the link (e.g. any beertap-log has it). Do not put too much money on the linked wallet and also make sure, that when you pay there is a certain distance to other people around you. Voucherlinks can only be generated by LNbits and the NFC-Brrr tool. Voucherlinks can be overwritten without any authentication.
Boltcards work in a different way, the allow the setting of filters like amount per transaction/per day, a PIN that is needed before payments. Also it catches a new request on each tap that cannot be replayed and is on top only valid, if the physical ID of the card matches to the request. Boltcard keys can be generated by the Bolt Card Wallet, LNbits and BTCpay. Boltcards can only be overwritten with a special set of delete-keys that you get, when you write the card. Please back those up!
That being said, lets explore, how both of them can be generated.
Create a Boltcard with LNbits or BTCpay
One way to create and run a Boltcard wallet yourself is with the BoltCard Wallet App (Boltcard capable fork of Blue Wallet). To run this in a self-sovereign way youll need to also run a BoltCard Hub (similar to LNDhub) to genereate the keys and write the cards with it. At the moment there is no open BoltCardHub, so if you do not run one yourself, this is no option. In the near future you can find it as app in your node-appstores like on Nirvati.
If you are not too tech-savy please read on – there are more solutions.
The BTCpay process is described here. For LNbits there are videos as a guide through the setup that might also help even if you do it on BTCpay or with the Bolt Card Wallet for a better understanding.
The described process sets up the secure version of an NFC Tag aka “Boltcard”. You can also find a textual description of the process here if you prefer reading.
It basically will generate a CREATE and also a WIPE key in case you ever want to rewrite your card.
🚨🚨🚨 The wipe-keys generated are needed when you want to rewrite your card in the future,
DO NOT DELETE THOSE KEYS without a backup 🚨🚨🚨
A .json with the wipe-keys file will be force-downloaded at the end of the writing process with which you can recover those wallets. Do not play with 🔥 deleting the keys, card or even the wallet in LNbits/BTCpay just because you have that file. If you delete the wallet or the card or if you regenerate your keys just because you can, your old setup will be gone from the database and without a backup you will probably not be able to rewrite your card ever again.
If you want to gift a Boltcard not with a plain voucherlink (recommended because of easier rewrite) but with a Boltcard, please include the following data for the user to be able to make full use of your present.
Rewrite a Boltcard
Got a prewritten Bolt Card and now you want to connect another wallet to it ? This is a bit tricky.
First you need to start deleting the old values with the wipe keys that you need to get from ->where the card was written<-; If you have a CoinCorner Boltcard you will have to start the wiping process by collecting those from there by going through the KYC process. If you have written a tag with the LNbits or BTCpay boltcard extension you will need the wipe keys of this card from there to be able to do so.
If putting in the old keys fails x times you will have to succeed the same amount of taps with the right ones before it will be unlocked again (You will be shown error 91AD until then whatever you type in). If you do not have the wipe-keys you can stop right there.. You can find more info on that security idea behind it in this document from NXP chapter 7.4.
To make all this easier LNbits and BTCpay offer a QR-Code that represents the wipe-keys needed to do so in the Bolt Card Writer App. Please scroll forward in the following video to minute 2:40. First you will need to delete the old ones and only then you can rewrite it.
Super nerdy experts can do this in a much more painful, manual way with the help of this written tutorial using the NXP-Write Tool. #totally_not_recommended
If you don´t have the wipe keys for your old setup there is no way of writing to those tag ever again. But still you now own a very rare collectible !
Remember that this is a security feature of NTAG424 cards and has nothing to do with the Boltcard-service or -app.
Tipping cards and voucher
If you want to give away cards on a conference or as voucher we suggest using a NTAG424 but write a static lnurl to it with the LNbits extension “withdraw” instead of the “Boltcards” extension. This way users can easily rewrite it with their own Boltcard, when the voucher funds are redeemed. We do not recommend to use a static voucher lnurlw as a debit card or for more than pocket money amounts.
Voucher do not require advanced security measures because the link will not be used for long like e.g. as long as your event goes or as a present to a waiter or friend that will be redeemed within one transaction soon. The missing security features would also allow for tags fromon NTAG21* to be used for this – which are usually cheaper but dont allow for a lot of bitcoin use-cases afterwards except making another voucher out of it.
You can also find an english textual description on how to write those here. The longer process including putting your LNbits into clearnet is explained in the following german video. Just set it to auto-translate. If your LNbits already is in clearnet scroll forward on that part.
arbadacarba made a video on how to upload a nice custom LNbits design (templates are linked in the shownotes) for gifting such tipping cards.
Voucher cards in a batch
For events voucher are the most recommended give-away – type to spend on a venue mostly because the easy rewrite process and low security measures needed. This sort of static links can also be used for games on events where for example some out of all cards have a winning-option. If you are into tinkering you can e.g. turn something on (lights, music, a confetti machine,..) when a certain card is used at a beertap or even on the venue 😛 If you want to do something like this your beertap-code will need to check for certain UIDs (tag-ID) being used which only can work if you do not define them with “rolling ID” which is only an option on the BTCpay plugin. See the links about building for more details.
The process of generating and writing a lot of cards is supereasy with the https://brrr.slaapyhoofd.nl/ which acts atop of LNbits. With that tool you can set up an amount of wallets each with lnurlw / lnurlp / lndhub in a batch and write one of those to NFC tags and other onto e.g. stickers in one workflow. Choose as you wish. Github-Code at https://github.com/slaapyhoofd/brrr
Tags used for voucher can be any >NTAG2**.
** Note that LNURLw is just suitable for vouchers e.g. as a give-away for an event. Sort-of-debitcards should still be done with the boltcard-extension on a NTAG424! If you produce a lot of cards, handle the amount of requests with care and adapt your killswitch option in LNbits accordingly ☠️
If you have any questions do not hesitate to contact us.
Have fun, plebs !