# Steps for making a bolt card with NXP TagXplorer software

## Introduction

Here we describe how to create your own bolt card with NXP TagXplorer software.

## Resources
 
- some cards
  - NXP DNA 424 NTAG cards

- a good NFC reader/writer
  - Identiv uTrust 3700 F

- software
  - [NXP TagXplorer software](https://www.nxp.com/products/rfid-nfc/mifare-hf/mifare-desfire/tagxplorer-pc-based-nfc-tag-reader-writer-tool:TAGXPLORER)
  - [Java Run Time environment](https://java.com/de/download/)

## Steps

### Connect to the card
- start the NFC TagXplorer software
- `Connect` to the NFC card reader
- place a card on the reader and click `Connect Tag`
- verify the card description

![tag connected](images/con.webp)

### Read the card
- select `NDEF Operations` and `Read NDEF`
- if you get this error, click `Format NDEF` and try again

![bytes to read should be greater than zero](images/btr.webp)

- verify that the read completes without erroring

### Start to set up the URI template
- select `NTAG Operations`, `Mirroring Features` and `NTAG 424 DNA`
- set `Protocol` to `https://`
- set `URI Data` to
```
lnurlw://card.yourdomain.com/ln
```
- select `Add PICCDATA` and `Enable SUN Message`
- adjust the `URI Data` to
```
lnurlw://card.yourdomain.com/ln?p=00000000000000000000000000000000&c=0000000000000000
```
- click after `p=` and note the p_position (41 in this case)
- click after `c=` and note the c_position (76 in this case)
- select `Write To Tag`

![NDEF message written successfully](images/nfwc.webp)

- now go back to `NDEF Operations` and `Read NDEF`
- verify that the `NDEF Payload Info` is as expected

![read payload as text](images/rd-txt.webp)
	 
### Finish setting up the URI template
- notice that the URI shows as `https://lnurlw://card ...` but we want `lnurlw://card ...`
- go to `NTAG Operations` and `NTAG 424 DNA`
- select `Read/Write data`
- select `File No` as `NDEF File - 02`
- click `Read`

![read NDEF data](images/rdh.webp)

- the NDEF file is `0057D1015355046C6E75726C ...`.
- look for the bytes `5504` (6 bytes from the start)
- `04` is the code for `https://` URI prepending
- change the `04` to `00` to indicate no prepending for the URI

![write NDEF data](images/wrh.webp)

- click `Write`

![written successfully](images/ws.webp)

- now go back to `NDEF Operations` and `Read NDEF`
- verify that the `NDEF Payload(HEX) Info` is similar to that shown

![read payload as hex](images/nrd.webp)

- copy the hex data and convert to text, without the `0x00` prefix
- verify you have your expected `URI data` value  

[Online hex to text tool](http://www.unit-conversion.info/texttools/hexadecimal/)

![hex to text online tool](images/hex.webp)

### Set up the SUN authentication message
- go to `NTAG Operations` and `NTAG 424 DNA`
- select `Security Management` and click `Authentiate First`

![success dialog](images/avs.webp)

- select `Get/Change File Settings`

![success dialog](images/gfs.webp)

- set up the values in the order shown

![file and SDM options with field entry order](images/fs-add.webp)

- select `Change File Settings`

![success message](images/cfs.webp)

- now go back to `NDEF Operations` and `Read NDEF`
- convert the hex data to text again
- verify that the `p` and `c` values are non zero
- select `Read NDEF` again
- convert the hex data to text again
- verify that the `p` and `c` values are in the right place
- verify that the `p` and `c` values change on each read
 
### Change the application keys
- go to `NTAG Operations` and `NTAG 424 DNA`
- select `Security Management`
- select `Authenticate`
- leave the `Card Key No` set to `00`
- leave the `Key` value set to `00000000000000000000000000000000` if not changed yet
- click `Authenticate First`

![success message](images/avs.webp)

- select `Change Key`
- select the `Card Key No` to change the key value for `00` to `04`
- leave the `Old Key` value set to `00000000000000000000000000000000` if not changed yet
- enter a `New Key` value as required
- enter a `New Key Version` value of `00` or as required to keep track of your keys
- click `Change Key`

![success message](images/ccs.webp)

- repeat this to change all 5 application keys to your own values

### Lock the card
- go to `NTAG Operations` and `NTAG 424 DNA`
- select `Security Management` and click `Authentiate First`
- select `Get/Change File Settings`
- adjust the `Access Rights` settings as shown

![success message](images/lock.webp)

## Testing
- set up a [bolt card service](INSTALL.md)
- add a record in the database for the new card
- use a merchant point of sale to scan your bolt card, e.g. [Breez wallet](https://breez.technology/)
- watch the bolt card service logs and verify that the requests are received and processed
