HF — 13.56 MHz
One frequency, most of the RFID you'll ever touch — payments, transit, passports, NFC, toys and badges.
High-frequency RFID uses exactly one frequency: 13.56 MHz, an internationally agreed band that's free to use worldwide. That one fact explains a lot of its success: a card made in one country works on a reader in any other.
#The sweet spot
- A small, cheap antenna. At 13.56 MHz a few flat turns around the edge of a card or sticker is enough, so the antenna can be etched or printed. No winding needed.
- Still near field. The wavelength is 22 m, so cards are read inside the near field by magnetic coupling, just like LF. Range stays short and predictable.
- Fast enough for real crypto. Data rates start at 106 kbit/s, about 50× faster than typical LF. That leaves time for proper public-key cards, payment cryptograms and encrypted sessions.
- Mean it to tap it. A few centimetres means intent: you chose to pay, you chose to open the door.
#The family
| Standard | Range | You know it as |
|---|---|---|
| ISO 14443 | up to ~10 cm | payment cards, transit, passports, phones, most access cards |
| ISO 15693 | up to ~1 m with a big antenna | library books, ski passes, some access cards |
| FeliCa | up to ~10 cm | transit and payments in Japan |
| NFC | a few cm | the phone-friendly layer on top of all three |
#Where you meet it
Contactless payments, phone wallets, passports, transit cards, office badges, hotel keys, toys, NFC stickers and security keys. If you tap it, it's almost certainly HF.
#Things that get in the way
- Metal behind the tag. Metal soaks up the field and detunes the coil. Tags meant for metal surfaces have a ferrite sheet behind the antenna.
- Card clash. Two cards in one wallet can both answer. Readers can sort that out with anticollision, but a ticket gate may pick the wrong card, so tap the one you mean.
- Phone cases. Thick or metal-lined cases can stop a phone from reading.
With Your phone
Install NXP TagInfo and tap a card. It identifies the chip family, the UID and anything readable without keys.
With Proxmark3
hf search tries every HF protocol and identifies the card. hf 14a info
gives detail on ISO 14443-A cards.
With Flipper Zero
NFC → Read. It identifies the card type and shows the UID and any data it can read without keys.
With USB NFC reader
With libnfc installed, nfc-list shows any card on the reader along with its
type and UID.