Near-field communication
Near-field communication (NFC) is a set of communication protocols that enables communication between two electronic devices over a distance of 4 cm (1 in) or less. NFC offers a low-speed connection through a simple setup that can be used to bootstrap more-capable wireless connections. Like other "proximity card" technologies, NFC is based on inductive coupling between two so-called antennas present on NFC-enabled devices—for example a smartphone and a printer—communicating in one or both directions, using a frequency of 13.56 MHz in the globally available unlicensed radio frequency ISM band using  the ISO/IEC 18000-3 air interface standard at data rates ranging from 106 to 424 kbit/s. The standards were provided by the NFC Forum. The forum was responsible for promoting the technology and setting standards and certifies device compliance. Secure communications are available by applying encryption algorithms as is done for credit cards and if they fit the criteria for being considered a personal area network. NFC standards cover communications protocols and data exchange formats and are based on existing radio-frequency identification (RFID) standards including ISO/IEC 14443 and FeliCa. The standards include ISO/IEC 18092 and  those defined by the NFC Forum. In addition to the NFC Forum, the GSMA group defined a platform for the deployment of GSMA NFC Standards within mobile handsets. GSMA's efforts include Trusted Services Manager, Single Wire Protocol, testing/certification and secure element. NFC-enabled portable devices can be provided with application software, for example to read electronic tags or make payments when connected to an NFC-compliant system. These are standardized to NFC protocols, replacing proprietary technologies used by earlier systems. A patent licensing program for NFC is under deployment by France Brevets, a patent fund created in 2011 . This program was under development by Via Licensing Corporation, an independent subsidiary of Dolby Laboratories, and was terminated in May 2012. A platform-independent free and open source NFC library, , is available under the GNU Lesser General Public License. Present and anticipated applications include contactless transactions, data exchange and simplified setup of more complex communications such as Wi-Fi. In addition, when one of the connected devices has Internet connectivity, the other can exchange data with online services. History. NFC is rooted in radio-frequency identification technology (known as RFID) which allows compatible hardware to both supply power to and  communicate with an otherwise unpowered and passive electronic tag using radio waves. This is used for identification, authentication and tracking. Similar ideas in advertising and industrial applications were not generally successful commercially, outpaced by technologies such as QR codes, barcodes and UHF RFID tags. Ultrawide Band (UWB) another radio technology has been hailed as a future possible alternatives to NFC Technology due to further distances of data transmission, as well as Bluetooth and wireless technology. Design. NFC is a set of short-range wireless technologies, typically requiring a separation of 10 cm or less. NFC operates at 13.56 MHz on  ISO/IEC 18000-3 air interface and at rates ranging from 106 kbit/s to 424 kbit/s. NFC always involves an initiator and a target; the initiator actively generates an RF field that can power a passive target. This enables NFC targets to take very simple form factors such as unpowered tags, stickers, key fobs, or cards. NFC peer-to-peer communication is possible, provided both devices are powered. NFC tags contain data and are typically read-only, but may be writable. They can be custom-encoded by their manufacturers or use NFC Forum specifications. The tags can securely  store personal data such as debit and credit card information, loyalty program data, PINs and networking contacts, among other information. The NFC Forum defines four types of tags that provide different communication speeds and capabilities in terms of configurability, memory, security, data retention and write endurance. As with proximity card technology, NFC uses inductive coupling between two nearby loop antennas effectively forming an air-core transformer. Because the distances involved are tiny compared to the wavelength of electromagnetic radiation (radio waves) of that frequency (about 22 meters), the interaction is described as near field. Only an alternating magnetic field is  involved so that almost no power is actually radiated in the form of radio waves (which are electromagnetic waves, also involving an oscillating electric field); that essentially prevents interference between such devices and any radio communications at the same frequency or with other NFC devices much beyond its intended range. They operate within the globally available and unlicensed radio frequency ISM band of 13.56 MHz. Most of the RF energy is concentrated in the ±7 kHz bandwidth allocated for that band, but the emission's spectral width can be as wide as 1.8 MHz in order to support high data  rates. Working distance with compact standard antennas and realistic power levels could be up to about 20 cm (but practically speaking, working distances never exceed 10 cm). Note that because the pickup antenna may be quenched in an eddy current by nearby metallic surfaces, the tags may require a minimum separation from such surfaces. The ISO/IEC 18092 standard supports data rates of 106, 212 or 424 kbit/s. The communication takes place between an active "initiator" device and a target device which may either be: 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%. Every active NFC device can work in one or more of three modes: NFC tags are passive data stores which can be read, and under some circumstances written to, by an NFC device. They typically contain data ( between 96 and 8,192 bytes) and are read-only in normal use, but may be rewritable. Applications include secure personal data storage (e.g. debit or credit card information, loyalty program data, personal identification numbers (PINs), contacts ). NFC tags can be custom-encoded by their manufacturers or use the industry specifications. Security. Although the range of NFC is limited to a few centimeters, standard plain NFC is not protected against eavesdropping and can be vulnerable to data modifications. Applications may use higher-layer cryptographic protocols to establish a secure channel. 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 multiple parameters, but is typically less than 10 meters. Also, eavesdropping is highly affected by the communication mode . A passive device that doesn't generate its own RF field is much harder to eavesdrop on than an active device. An attacker can typically eavesdrop within 10 m of an active device and 1 m for passive devices. Because NFC devices usually include ISO/IEC 14443 protocols, relay attacks are feasible. For this attack the adversary forwards the request of the reader to the victim and relays its answer to the reader in real time, pretending to be the owner of the victim's smart card. This is similar to a man-in-the-middle attack. One code example  demonstrates a relay attack using two stock commercial NFC devices. This attack can be implemented using only two NFC-enabled mobile phones. Standards. NFC standards cover communications protocols and data exchange formats, and are based on existing RFID standards including ISO/IEC 14443 and FeliCa. The standards include ISO/IEC 18092 and those defined by the NFC Forum. ISO/IEC. NFC is 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. They also define the transport protocol, including protocol activation and data-exchange methods. The air interface for NFC is standardized in: NFC incorporates a variety of existing standards including ISO/IEC 14443 Type A and Type B, and FeliCa. NFC-enabled phones work at a basic level with existing readers. In "card emulation mode" an NFC device should transmit, at a minimum, a unique ID number to a reader. In addition, NFC Forum defined a common data format called "NFC Data Exchange Format" (NDEF) that can store and transport items ranging  from any MIME-typed object to ultra-short RTD-documents, such as URLs. The NFC Forum added the "Simple NDEF Exchange Protocol" (SNEP) to the spec that allows sending and receiving messages between two NFC devices. GSMA. The GSM Association (GSMA) is a trade association representing nearly 800 mobile telephony operators and more than 200 product and service companies across 219 countries. Many of its members have led NFC trials and are preparing services for commercial launch. GSM is involved with several initiatives: 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 potential for NFC local wireless mobile communication. NFC Forum. NFC Forum is a non-profit industry association formed on March 18, 2004, by NXP Semiconductors, Sony and Nokia to advance the use of NFC wireless interaction in consumer electronics, mobile devices and PCs. Standards include the four distinct tag types that provide different communication speeds and capabilities covering flexibility, memory, security, data retention and write endurance. NFC Forum promotes implementation and standardization of NFC technology to ensure interoperability between devices and services. As of January 2020, the NFC Forum had  over 120 member companies. NFC Forum promotes NFC and certifies device compliance and whether it fits in a personal area network. Other standardization bodies. GSMA defined a platform for the deployment of GSMA NFC Standards within mobile handsets. GSMA's efforts include, Single Wire Protocol, testing and certification and secure element. The GSMA standards surrounding the deployment of NFC protocols (governed by NFC Forum) on mobile handsets are neither exclusive nor universally accepted. For example, Google's deployment of Host Card Emulation on Android KitKat provides for software control of a universal radio. In this HCE Deployment the NFC protocol  is leveraged without the GSMA standards. Other standardization bodies involved in NFC include: Applications. NFC allows one- and two-way communication between endpoints, suitable for many applications. NFC devices can act as electronic identity documents and keycards. They are used in contactless payment systems and allow mobile payment replacing or supplementing systems such as credit cards and electronic ticket smart cards. These are sometimes called "NFC/CTLS" or "CTLS NFC", with "contactless" abbreviated as "CTLS". NFC can be used to share small files such as contacts and for bootstrapping fast connections to share larger media such as photos, videos, and  other files. Commerce. NFC devices can be used in contactless payment systems, similar to those used in credit cards and electronic ticket smart cards and allow mobile payment to replace/supplement these systems. In Android 4.4, Google introduced platform support for secure NFC-based transactions through Host Card Emulation (HCE), for payments, loyalty programs, card access, transit passes and other custom services. HCE allows any Android 4.4 app to emulate an NFC smart card, letting users initiate transactions with their device. Apps can use a new Reader Mode to act as readers for HCE cards and other NFC-based transactions . On September 9, 2014, Apple announced support for NFC-powered transactions as part of Apple Pay. With the introduction of iOS 11, Apple devices allow third-party developers to read data from NFC tags. Bootstrapping other connections. NFC offers a low-speed connection with simple setup that can be used to bootstrap more capable wireless connections. For example, Android Beam software uses NFC to enable pairing and establish a Bluetooth connection when doing a file transfer and then disabling Bluetooth on both devices upon completion. Nokia, Samsung, BlackBerry and Sony have used NFC technology to pair Bluetooth headsets, media players  and speakers with one tap. The same principle can be applied to the configuration of Wi-Fi networks. Samsung Galaxy devices have a feature named S-Beam—an extension of Android Beam that uses NFC (to share MAC Address and IP addresses) and then uses Wi-Fi Direct to share files and documents. The advantage of using Wi-Fi Direct over Bluetooth is, that it permits much faster data transfers, running up to 300 Mbit/s. Social networking. NFC can be used for social networking, for sharing contacts, text messages and forums, links to photos, videos or files and entering  multiplayer mobile games. Identity and access tokens. NFC-enabled devices can act as electronic identity documents found in Passports and ID cards, and keycards for the use in Fare cards, Transit passes, Login Cards, Car key and Access badges . NFC's short range and encryption support make it more suitable than less private RFID systems. Smartphone automation and NFC tags. NFC-equipped smartphones can be paired with NFC Tags or stickers that can be programmed by NFC apps. These programs can allow a change of phone settings, texting, app launching, or command execution. Such apps do not rely on a  company or manufacturer, but can be utilized immediately with an NFC-equipped smartphone and an NFC tag. The NFC Forum published the Signature Record Type Definition (RTD) 2.0 in 2015 to add integrity and authenticity for NFC Tags. This specification allows an NFC device to verify tag data and identify the tag author. Gaming. NFC has been used in video games starting with . These are customizable figurines which contain personal data with each figure, so no two figures are exactly alike. Nintendo's Wii U was the first system to include NFC technology out of the box via the GamePad . It was later included in the Nintendo 3DS range (being built into the New Nintendo 3DS/XL and in a separately sold reader which uses Infrared to communicate to older 3DS family consoles). The amiibo range of accessories utilize NFC technology to unlock features. Sports. Adidas Telstar 18 is a soccer ball that contains an NFC chip within. The chip enables users to interact with the ball using a smartphone. Bluetooth comparison. NFC and Bluetooth are both relatively short-range communication technologies available on mobile phones. NFC operates at slower speeds than Bluetooth and has a much shorter range, but  consumes far less power and doesn't require pairing. NFC sets up more quickly than standard Bluetooth, but has a lower transfer rate than Bluetooth low energy. With NFC, instead of performing manual configurations to identify devices, the connection between two NFC devices is automatically established in less than .1 second. The maximum data transfer rate of NFC (424 kbit/s) is slower than that of Bluetooth V2.1 (2.1 Mbit/s). NFC's maximum working distance of less than 20 cm reduces the likelihood of unwanted interception, making it particularly suitable for crowded areas that complicate correlating a signal with  its transmitting physical device (and by extension, its user). NFC is compatible with existing passive RFID (13.56 MHz ISO/IEC 18000-3) infrastructures. It requires comparatively low power, similar to the Bluetooth V4.0 low-energy protocol. However, when NFC works with an unpowered device (e.g. on a phone that may be turned off, a contactless smart credit card, a smart poster), the NFC power consumption is greater than that of Bluetooth V4.0 Low Energy, since illuminating the passive tag needs extra power. Devices. In 2011, handset vendors released more than 40 NFC-enabled handsets with the Android mobile operating system . BlackBerry devices support NFC using BlackBerry Tag on devices running BlackBerry OS 7.0 and greater. MasterCard added further NFC support for PayPass for the Android and BlackBerry platforms, enabling PayPass users to make payments using their Android or BlackBerry smartphones. A partnership between Samsung and Visa added a 'payWave' application on the Galaxy S4 smartphone. In 2012, Microsoft added native NFC functionality in their mobile OS with Windows Phone 8, as well as the Windows 8 operating system. Microsoft provides the "Wallet hub" in Windows Phone 8 for NFC payment, and can integrate multiple NFC payment services within a single  application. In 2014, iPhone 6 was released from Apple to support NFC. and since September 2019 in iOS 13 Apple now allows NFC tags to be read out as well as labeled using an NFC app. Deployments. , hundreds of NFC trials had been conducted. Some firms moved to full-scale service deployments, spanning one or more countries. Multi-country deployments include Orange's rollout of NFC technology to banks, retailers, transport, and service providers in multiple European countries, and Airtel Africa and Oberthur Technologies deploying to 15 countries throughout Africa.