I scanned my new Bitkey hardware wallet with the NXP TagInfo Android app and then compared the results to Bitkey’s published firmware. Some neat details popped out.
First surprise: Bitkey is not behaving like a simple NFC tag.
It presents itself as an ISO 14443-4 smart card and communicates using ISO 7816-4 APDUs. This is the same general command/response model used by smart cards and payment cards.
My scan showed:
UID: 57:31:41:30
ATQA: 0x0200
SAK: 0x20
That UID looks random until you convert it from hex to ASCII:
57 31 41 30 = W1A0
Bitkey’s public firmware hardcodes exactly that NFC identity.
So when your phone “scans” Bitkey, it isn’t reading the Bitcoin private key or some static NFC record.
The flow is more like:
1. Phone → sends command over NFC
2. Bitkey → processes it internally
3. Bitkey → signs/approves
4. Phone ← receives the response
The private key stays inside the hardware.
Another interesting detail: TagInfo identified the “IC manufacturer” as Infineon Technologies AG. But that appears to be a fingerprinting mistake.
Bitkey is software-emulating the smart-card interface, and its public NFC implementation uses STMicroelectronics’ NFC stack. The W1A0 UID is software-defined, not a factory chip serial number.
TagInfo also claimed it found things like a GlobalPlatform card manager and multiple Type 4 Tag applications. That looks like another artifact of Bitkey’s NFC compatibility layer responding successfully to generic smart-card probes.
In other words: Bitkey can fool normal NFC tools into thinking it’s a more conventional smart card than it really is.
My biggest interesting takeaway:
Bitkey’s NFC connection is basically a very short-range smart-card-style communication channel to a separate cryptographic computer.
Your phone isn’t “reading the wallet.” It’s asking the wallet to perform authenticated cryptographic operations and getting the results back over NFC.
I had a lot of fun confirming all this on my own. Elegant design and nice work, Bitkey (nprofile…nkd7).
