Definitions

communication interface

Near Field Communication

Near Field Communication or NFC, is a short-range high frequency wireless communication technology which enables the exchange of data between devices over about a 10 centimetre (around 4 inches) distance. The technology is a simple extension of the ISO 14443 proximity-card standard (contactless card, RFID) that combines the interface of a smartcard and a reader into a single device. An NFC device can communicate with both existing ISO 14443 smartcards and readers, as well as with other NFC devices, and is thereby compatible with existing contactless infrastructure already in use for public transportation and payment. NFC is primarily aimed at usage in mobile phones.

Essential specifications

  • Like ISO 14443, NFC communicates via magnetic field induction, where two loop antennas are located within each other's near field, effectively forming an air-core transformer. It operates within the globally available and unlicensed radio frequency ISM band of 13.56 MHz, with a bandwidth of almost 2 MHz.
  • Working distance with compact standard antennas: up to 20 cm
  • Supported data rates: 106, 212, or 424 kbit/s
  • There are two modes:
    • Passive Communication Mode: The Initiator device provides a carrier field and the target device answers by modulating existing field. In this mode, the Target device may draw its operating power from the Initiator-provided electromagnetic field, thus making the Target device a transponder.
    • Active Communication Mode: Both Initiator and Target device communicate by alternately generating their own field. A device deactivates its RF field while it is waiting for data. In this mode, both devices typically need to have a power supply.

Baud Active device passive device
424 kBd Manchester, 10% ASK Manchester, 10% ASK
212 kBd Manchester, 10% ASK Manchester, 10% ASK
106 kBd Modified Miller, 100% ASK Manchester, 10% ASK

  • NFC employs two different codings to transfer data. If an active device transfers data at 106 kbit/s, a modified Miller coding with 100% modulation is used. In all other cases Manchester coding is used with a modulation ratio of 10%.
  • NFC devices are able to receive and transmit data at the same time. Thus, they can check the radio frequency field and detect a collision if the received signal does not match with the transmitted signal.

Uses and applications

NFC technology is currently mainly aimed at being used with mobile phones. There are three main use cases for NFC:

  • card emulation: the NFC device behaves like an existing contactless card
  • reader mode: the NFC device is active and read a passive RFID tag, for example for interactive advertising
  • P2P mode: two NFC devices are communicating together and exchanging information.

Plenty of applications are possible, such as:

  • Mobile ticketing in public transport — an extension of the existing contactless infrastructure.
  • Mobile payment — the device acts as a debit/ credit payment card.
  • Smart poster — the mobile phone is used to read RFID tags on outdoor billboards in order to get info on the move.
  • Bluetooth pairing — in the future pairing of Bluetooth 2.1 devices with NFC support will be as easy as bringing them close together and accepting the pairing. The process of activating Bluetooth on both sides, searching, waiting, pairing and authorization will be replaced by a simple "touch" of the mobile phones.

Other applications in the future could include:

A patent licensing program for NFC is currently under development by Via Licensing Corporation, an independent subsidiary of Dolby Laboratories.

NFC vs Bluetooth

NFC Bluetooth
Network Type Point-to-point Point-to-multipoint
Range < 0.2 m 10 m
Speed 424 kbit/s 2.1 mbit/s
Set-up time < 0.1 s 6 s
Compatible with RFID Yes No
NFC and Bluetooth are both short-range communication technologies which have recently been integrated into mobile phones. The significant advantage of NFC over Bluetooth is the shorter set-up time. Instead of performing manual configurations to identify Bluetooth devices, the connection between two NFC devices is established at once (under a tenth of a second). To avoid the complicated configuration process, NFC can be used for the set-up of wireless technologies, such as Bluetooth. The maximum data transfer rate of NFC (424 kbit/s) is slower than Bluetooth (2.1 mbit/s). With less than 20 cm, NFC has a shorter range, which provides a degree of security and makes NFC suitable for crowded areas where correlating a signal with its transmitting physical device (and by extension, its user) might otherwise prove impossible. In contrast to Bluetooth, NFC is compatible with existing RFID structures. NFC can also work when one of the devices is not powered by a battery (e.g. on a phone that may be turned off, a contactless smart credit card, a smart poster, etc.).

Standardization bodies and industry projects

Standards

It was approved as an ISO/IEC standard on December 8 2003 and as an ECMA standard later on.

NFC is an open platform technology standardized in ECMA-340 and ISO/IEC 18092. These standards specify the modulation schemes, coding, transfer speeds and frame format of the RF interface of NFC devices, as well as initialization schemes and conditions required for data collision-control during initialization-for both passive and active NFC modes. Furthermore, they also define the transport protocol, including protocol activation and data-exchange methods. Air interface for NFC is standardized in: ISO/IEC 18092 / ECMA-340 : Near Field Communication Interface and Protocol-1 (NFCIP-1) ISO/IEC 21481 / ECMA-352 : Near Field Communication Interface and Protocol-2 (NFCIP-2)

NFC incorporates a variety of pre-existing standards including ISO 14443 both A (normal) and B (banking/short range), ISO 15693, and FeliCa. NFC enabled phones thus show basic interoperability with the preexisting reader infrastructure. Especially in "card emulation mode" a NFC device should at least transmit a unique ID number to a pre-existing reader.

NFC Forum has in addition defined a common data format called NDEF, which can be used to store and transport different kinds of items, ranging from any MIME-typed object to ultra-short RTD-documents, such as URLs.

NDEF is conceptually very similar to MIME. It is a dense binary format of so-called "records", in which each record can hold a different type of object. By convention, the type of the first record defines the context of the entire message.

NFC Forum

The NFC Forum is a non-profit industry association founded on March 18, 2004 by NXP Semiconductors, Sony and Nokia to advance the use of NFC short-range wireless interaction in consumer electronics, mobile devices and PCs. The NFC Forum will promote implementation and standardization of NFC technology to ensure interoperability between devices and services. In September 2007, there were over 130 members of the NFC Forum.

GSMA

The GSM Association (GSMA) is the global trade association representing 700 mobile phone operators across 218 countries of the world.

They have launched two initiatives:

On 13 February 2007, they published a white paper on NFC to give the point of view of mobile operators on the NFC ecosystem.

  • the Pay buy mobile initiative seeks to define a common global approach to using Near Field Communications (NFC) technology to link mobile devices with payment and contactless systems. To date, 30 mobile operators have joined this initiative.

StoLPaN

StoLPaN (‘Store Logistics and Payment with NFC’) is a pan-European consortium supported by the European Commission’s Information Society Technologies program. StoLPaN will examine the as yet untapped potential for bringing together the new kind of local wireless interface, NFC and mobile communication.

Other standardization bodies

Other standardization bodies are involved in NFC:

  • ETSI / SCP (Smart Card Platform) to specify the interface between the SIM card and the NFC chipset.
  • GlobalPlatform to specify a multi-application architecture of the secure element.
  • EMVCo for the impacts on the EMV payment applications.

Security aspects

Although the communication range of NFC is limited to a few centimeters, NFC alone does not ensure secure communications. In 2006, Ernst Haselsteiner and Klemens Breitfuß described different possible types of attacks.

NFC offers no protection against eavesdropping and is also vulnerable to data modifications. Applications have to use higher-layer cryptographic protocols (e.g., SSL) to establish a secure channel.

Eavesdropping

The RF signal for the wireless data transfer can be picked up with antennas. The distance from which an attacker is able to eavesdrop the RF signal depends on numerous parameters, but is typically a small number of meters. Also, eavesdropping is extremely affected by the communication mode. A passive device, which does not generate its own RF field is much harder to eavesdrop on than an active device.

Data modification

Data destruction is relatively easy to realize. One possibility to perturb the signal is the usage of an RFID jammer. There is no way to prevent such an attack, but if the NFC devices check the RF field while they are sending, it is possible to detect it.

Unauthorized modification of data, which results in valid messages, is much more complicated and demands a thorough understanding. In order to modify the transmitted data an intruder has to deal with the single bits of the RF signal. The feasibility of this attack, i.e., if it is possible to change the value of a bit from 0 to 1 or the other way around, is amongst others subject to the strength of the amplitude modulation. If data is transferred with the modified Miller coding and a modulation of 100%, only certain bits can be modified. A modulation ratio of 100% makes it possible to eliminate a pause of the RF signal, but not to generate a pause where no pause has been. Thus, only a 1 which is followed by another 1 might be changed. Transmitting Manchester encoded data with a modulation ratio of 10% permits a modification attack on all bits.

Relay attack

Because NFC devices are usually also implementing ISO 14443 functionality, the relay attack described are also feasible on NFC. For this attack the adversary has to forward the request of the reader to the victim and relay back its answer to the reader in real time, in order to carry out a task pretending to be the owner of the victim’s smart card.

Current trials

Europe

North America

Asia

See also

References

External links

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