When Limneos first tweeted about 'playing with' the NFC chip back on May 19th, the community was stunned. It was a first, nobody had been able to crack it before. His demo video shows him being able to read a number of different NFC tags. It wasn't until around two weeks later that he announced read and write data capabilities.
This came on the same day as iOS 11 was announced by Apple at WWDC 2017. Coincidentally, Apple has opened up the NFC chip a tiny bit to developers, if only to read NDEF messages. Turns out, this isn't particularly useful.
For now, the app is in the early stages and will undergo significant changes before being released, including the ability to write different types of data.
After chatting with Limneos a bit, this is what he had to say:
How long did it take you to achieve read/write access?
"I knew that iPhone has an NFC chip since iPhone 6, so I thought I should take a look at the methods used to access the chip. I had dealt before in the past with directly accessing hardware like proximity sensor (CallBar), Touch ID (BioProtect) and audio hardware (AudioRecorder, Voice Changer, AnsweringMachine) and I took a similar approach to figure out how NFC works on iPhone: I took me a couple of hours to achieve read access."
Can you talk about any major hurdles you had to overcome and how you managed to?
"On iOS 10, it's pretty easy for the reading part. Write access and NDEF messages (reading data from the tag) took me about a week of mostly research since I knew nothing about NFC protocols and I had to read around a lot. This was the hardest part, learning how NFC protocols work from scratch.
But then I started digging deeper: The methods one iOS give very little info about the tags (only its ID) , so I had to directly access the driver and extract more info from the tags (SAK, ATQA, RF Interface, RF Technology, Transfer Protocol etc) which took me another week of research and it paid well: The app can now supply all this info and in addition, it can now put the chip in card emulation mode, meaning that you can use your iPhone as a tag and maybe open your office door. Direct access to the driver gives unlimited potential."
How does Apple opening up the NFC chip on the iPhone 7 effect this tweak?
"It is exciting to see Apple opening up stuff and I'm glad it happened at the time I started learning about NFC. I already have an App Store app almost ready.
However, Apple API gives very limited access compared to my jailbreak app: You can only read NDEF messages. That's it. You can't even get the tag ID, you can't write to tags or format them to NDEF, which caused a lot of frustration to developers since they had to format a new tag on a Samsung first to make them readable on iOS. You don't get card emulation either. My tweak does all of the above. Hopefully, they will all open up in the future.
Therefore, this does not affect my tweak any more than it affected BioProtect when Apple "opened up" Touch ID API."
How much will it cost?
"Although the tweak is scheduled for release in a few days, I haven't settled on a price yet. This tweak is intended for home automation projects and professionals mostly, not everyone used NFC tags yet, but the price won't be much different than my other tweaks."
Would you consider open sourcing it or providing documentation for other devs?
"In the future, yes. I'll provide a fully documented API after I've gathered all required resources about NFC protocols."
Is there anything else you are working on that you can talk about?
"Yes, and I'm anxious to release NFCWriter so I can finish it. It's another surprise tweak that I think users will love it. This one is intended for everyone. It's a new UI as never seen before, that's all I can say :)"