This kit allows you to communicate with the NXP NTag 424 DNA NFC tag. You can always access it as an NDEF tag, but you can't write/modify it that way.
The DNA tag allows for encrypted access as well as authentication.
It has some pretty interesting features that allows this to be used for authenticity verification, as well as secure message storing.
Unfortunately, TapLinx (their communication library) is only available on Android.
Therefore, I decided to write a communication library for this chip.
To get started, load this as a git
package using the Swift package manager.
As of right now I'm not yet versioning, so just set the branch to main
.
You also have to do the NFC things to your project, including:
Info.plist
file:
<key>NFCReaderUsageDescription</key>
<string>NFC required to read/write NFC tags</string>
<key>com.apple.developer.nfc.readersession.iso7816.select-identifiers</key>
<array>
<string>D2760000850101</string>
</array>
In your code, you need to initialize a TagReaderSession:
var session: NFCTagReaderSession?
override func viewDidAppear(_ animated: Bool) {
if !NFCTagReaderSession.readingAvailable {
print("Reading not available")
}
print("View did appear")
tagReaderSession = NFCTagReaderSession(pollingOption: .iso14443, delegate: self)
tagReaderSession?.alertMessage = "Tap the tag to scan"
tagReaderSession?.begin()
}
Then you need to detect the tag:
func tagReaderSession(_ session: NFCTagReaderSession, didDetect tags: [NFCTag]) {
print("Tag found - yippeee")
let tag = tags.first!
print(tag)
session.connect(to: tag) { err in
if case let .iso7816(isoTag) = tag {
print("Cast successful")
let dna = DnaCommunicator()
dna.trace = true
dna.debug = true
dna.tagConfiguration = TagConfiguration()
dna.tag = isoTag
dna.begin { err in
dna.authenticateEV2First(keyNum: 0) { succ, err in
dna.getChipUid { result, err in
print(result)
DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + .seconds(1)) {
// Disconnect and go back to work
session.restartPolling()
}
}
}
}
}
}
}
This creates a default tag configuration (keys all zero) which matches the way the factory DNA samples come.
Because the communication is asynchronous, you need to do this command-embedded-within-command stuff.
To terminate the connection, we wait 1 second and then restartPolling
.
If you don't do this, the code will continually re-pick up on the tag and run it again and again.
Not necessarily problematic, and you can deal with it in other ways, but this seemed pretty straightforward.
Right now I've got the basic AES encrpytion methods set up.
You have three "basic" commands: nxpPlainCommand
(no encryption), nxpMacCommand
(MAC-authenticated command), and nxpEncryptedCommand
(full encryption of data), and also nxpSwitchedCommand
which allows the communication mode as a parameter.
Basically each function defined in the manual (like getChipUid
) will get a small wrapper function around the proper communication mode.
Right now, just a few functions are defined, but I'm planning on implementing most of them. They are pretty easy.
I also plan on having LRP communication setup soon.
I have a Go-related library for reading the LRP protocol: