NFC limitations
NFC on a phone is a short-range 13.56 MHz radio. Knowing its boundaries prevents a lot of myths.
| Capability | Phone? | Notes |
|---|---|---|
| Read/write NDEF tags | Yes | Text, URI, MIME, external, etc. |
| Detect tag tech (NfcA/B/F/V, IsoDep) | Yes | Detection only. |
| Host Card Emulation (custom AID) | Yes | Software card; see the HCE demo. |
| Clone a secure, encrypted credential | No | The secret key never leaves the card. |
| 125 kHz proximity cards | No | Different frequency & antenna hardware. |
| Sub-GHz (315/433/868 MHz) remotes | No | Not a phone radio at all. |
Tags vs credentials
An NDEF tag is like a tiny USB stick — readable, often writable. A secure access credential proves possession of a key using challenge-response and never reveals the key. Seeing a number on a badge does not mean the badge is cloneable; the visible number usually isn't the secret.
Reader mode & redaction
Fin uses Android's foreground reader mode, so it only reads while the NFC Lab is open — never in the background. UIDs are redacted by default; revealing the raw value is an explicit, warned action.