46 lines
2.2 KiB
Markdown
46 lines
2.2 KiB
Markdown
# Bolt card specification
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The bolt card system is built on the technologies listed below.
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- [LUD-03: withdrawRequest base spec.](https://github.com/fiatjaf/lnurl-rfc/blob/luds/03.md)
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- with the exception of maxWithdrawable which must be returned as higher than the actual maximum amount
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- [LUD-17: Protocol schemes and raw (non bech32-encoded) URLs.](https://github.com/fiatjaf/lnurl-rfc/blob/luds/17.md)
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- NFC Data Exchange Format (NDEF)
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- Replay protection
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- NXP Secure Unique NFC Message (SUN) technology as implemented in the NXP NTAG 424 DNA card
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Bolt card systems should implement the best possible privacy.
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- [Privacy levels](https://github.com/boltcard/boltcard/blob/main/docs/CARD_PRIVACY.md)
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Bolt card systems may optionally support these technogies.
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- [LUD-19: Pay link discoverable from withdraw link.](https://github.com/lnurl/luds/blob/luds/19.md)
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- [LUD-21: pinLimit for withdrawRequest](https://github.com/bitcoin-ring/luds/blob/withdraw-pin/21.md)
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## Bolt card and POS interaction
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the point-of-sale (POS) will read a NDEF message from the card, which changes with each use, for example
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```
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lnurlw://card.yourdomain.com?p=A2EF40F6D46F1BB36E6EBF0114D4A464&c=F509EEA788E37E32
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```
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the POS will then call your bolt card service here
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```
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https://card.yourdomain.com?p=A2EF40F6D46F1BB36E6EBF0114D4A464&c=F509EEA788E37E32
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```
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your bolt card service should verify the payment request as below and continue the standard LNURLw protocol as defined in LUD-03
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## Server side verification of the payment request
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- for the `p` value and the `SDM Meta Read Access Key` value, decrypt the UID and counter with AES
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- for the `c` value and the `SDM File Read Access Key` value, check with AES-CMAC
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- the authenticated UID and counter is used on the bolt card service to verify that the request is valid
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- the bolt card service must only accept an increasing counter value
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- additional validation rules can be added at the bolt card service, for example
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- card enable flag
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- card payment limit per transaction
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- card payment limit per day
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- allowed merchant list
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- verification of your location from your phone
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- the bolt card service can then make payment from a connected lightning node
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