Electronics notes/RFID and NFC notes
Contents
RFID, NFC, contactless smart cards
| This article/section is a stub — probably a pile of half-sorted notes, is not well-checked so may have incorrect bits. (Feel free to ignore, fix, or tell me) |
RFID (Radio-frequency identification) refers to a radio-frequency communication.
It often refers to a few specific designs, most of which are small and fairly easily hidden, particularly in/on/as small surfaces, relatively hidden devices.
On power
There are:
- passive tags
- which use an external source of power - often the communication itself (the reason for the large coiled antennae?)
- can be very small and thin, and therefore almost invisibly embedded in many things.
- common, because you don't need to care about power at all
- active tags
- battery-powered (...so limited lifespan and more expensive)
- can signal autonomously
- can be used over considerably larger distances
- can often communicate faster
- battery assisted passive (BAP)
- active tags that take negligible power from their batteries until triggered by communication
- cannot signal autonomously
Frequency use
| This article/section is a stub — probably a pile of half-sorted notes, is not well-checked so may have incorrect bits. (Feel free to ignore, fix, or tell me) |
Sorted approximately by common use:
- Low-frequency - 120-150kHz range
- for many countries often specifically ~125 or ~134.2 kHz
- these are more or less interchangeable
- You can fairly easily get readers (and writers) for this.
- High-frequency - 13.56 MHz (worldwide ISM(verify))
- Used in access badges, bank cards, library cards, loyalty cards, etc.
- Example: Mifare (which is sometimes known for )
- Ultra-high
- 433MHz
- 868MHz (EU unlicensed) and ~915MHz (US unlicensed) (think ISM)
- Microwave
- 2.4Hz and 5GHz - expensive tags
In term of 'what's in your wallet', it's probably mostly ~125 / ~134 kHz, and 13.56 MHz (verify)
Security criticism
RFID/NFC blocking wallet
Notes on cards and protocols
| This article/section is a stub — probably a pile of half-sorted notes, is not well-checked so may have incorrect bits. (Feel free to ignore, fix, or tell me) |
Proximity card
Early proxcards hold about as little as a magnetic stripe card.
Originally and mainly passive cards (typically at 125kHz, and correlated with ISO 7810 ID-1 sized cards),
powered by the reader so must be held close.
Active proxcards have a battery (lifetime generally on the order of a few years), and may be contacted at 2 meters or so, and a few more, useful for things like automated toll collection, gate opening, and such.
T5557
EM4100
Unsorted
NFC
NFC (Near Field Communication) can be thought of as an extesnsion.
It refers to things conforming to to ISO 14443 (proximity, ~10cm max range) or ISO 15693 (vicinity), and RFID usually refers to quite varied systems mostly described by the older ISO 18000.
In practice, the fact that RFID and NFC are used somewhat fuzzily means that people often use
- RFID to mean older simpler identitying (and often 125kHz) implementations,
- and NFC to mean mean newer, fancier, communicating (and often 13.56MHz) implementations.
The best way to be sure is to figure out the specific tech being used.
NDEF
Contactless smart card
| This article/section is a stub — probably a pile of half-sorted notes, is not well-checked so may have incorrect bits. (Feel free to ignore, fix, or tell me) |
Seems to refer to cards with
- a read-only CSN/UID
- a read-write IC
- some basic security
- usually in a ISO 7810 sized card (but also in keyfobs, etc.)
...which makes them a little more complex than classic proxcards.
Typically at 13.56 MHz ('RFID HF')
Protocols vary, but MiFare is one of the largest.
See
- ISO 14443 - proximity cards at 13.56MHz
- Type A and Type B, same protocol but varying modulation, coding, init
- ISO 15693 - vicinity cards (~1meter) at 13.56MHz
- ISO 18000 - varied systems at different frequencies
- below 135kHz
- at 13.56MHz
- at 2.45GHz
- within 860MHz .. 960MHz
- at 433MHz
https://en.wikipedia.org/wiki/Contactless_smart_card
Biometric passports
EMV
Contactless payment
The acronym originally stood for its creators, "Europay, Mastercard, and Visa" https://en.wikipedia.org/wiki/EMV
MiFare
https://en.wikipedia.org/wiki/MIFARE
NFC tags
Security
Calypso
https://en.wikipedia.org/wiki/Calypso_(electronic_ticketing_system)
CIPURSE
https://en.wikipedia.org/wiki/CIPURSE
EU identity cards
https://en.wikipedia.org/wiki/National_identity_cards_in_the_European_Economic_Area
