Essential specifications
- Like ISO/IEC 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 14 kHz.
- Working distance with compact standard antennas: up to 20 cm
- Supported data rates: 106, 212, 424 or 848 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.
- 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.
- 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.
- Electronic ticketing — airline tickets, concert/event tickets, and others
- Electronic money
- Travel cards
- Identity documents
- Mobile commerce
- Electronic keys — car keys, house/office keys, hotel room keys, etc.
- NFC can be used to configure and initiate other wireless network connections such as Bluetooth, Wi-Fi or Ultra-wideband.
NFC vs Bluetooth
-NFC and Bluetooth are both short-range communication technologies which have recently been integrated into mobile phones. To avoid the complicated configuration process, NFC can be used for the set-up of wireless technologies, such as Bluetooth.-The earlier advantage of NFC over Bluetooth with the shorter set-up time is still valid with standard Bluetooth protocol stack, but no more with Bluetooth V4.0 low energy protocol stack.
-With NFC, instead of performing manual configurations to identify devices, the connection between two NFC devices is established at once (faster than a tenth of a second).
-The maximum data transfer rate of NFC (424 kbit/s) is slower than Bluetooth V2.1 (2.1 Mbit/s). With less than 20 cm, NFC has a shorter range, which provides a limitation of threat. That mostly makes NFC suitable for crowded areas when correlating a signal with its transmitting physical device (and by extension, its user) becomes difficult.
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. An Open source device which is able to eavesdrop passive and active NFC communications is the Proxmark instrument.-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.
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