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Radio-Frequency Identification (RFID) See also Barcode & Barcode Scanner Radio-frequency identification (RFID) is an automatic identification method, relying on storing and remotely retrieving data using devices called RFID tags or transponders. An RFID tag is an object that can be applied to or incorporated into a product, animal, or person for the purpose of identification using radiowaves. Some tags can be read from several meters away and beyond the line of sight of the reader. Most RFID tags contain at least two parts. One is an integrated circuit for storing and processing information, modulating and demodulating a (RF) signal and can also be used for other specialized functions. The second is an antenna for receiving and transmitting the signal. A technology called chipless RFID allows for discrete identification of tags without an integrated circuit, thereby allowing tags to be printed directly onto assets at lower cost than traditional tags. Today, a significant thrust in RFID use is in enterprise supply chain management, improving the efficiency of inventory tracking and management. However, a threat is looming that the current growth and adoption in enterprise supply chain market will not be sustainable. A fair cost-sharing mechanism, rational motives and justified returns from RFID technology investments are the key ingredients to achieve long-term and sustainable RFID technology adoption [1].
History of RFID tags
An RFID tag used electronic toll collection
In 1946 Léon Theremin invented an espionage tool for the Soviet Union which retransmitted incident radio waves with audio information. Sound waves vibrated a diaphragm which slightly altered the shape of the resonator, which modulated the reflected radio frequency. Even though this device was a passive covert listening device, not an identification tag, it has been attributed as the first known device and a predecessor to RFID technology. The technology used in RFID has been around since the early 1920s according to one source (although the same source states that RFID systems have been around just since the late 1960s).[2][3][4][5] A similar technology, such as the IFF transponder invented by the United Kingdom in 1939, was routinely used by the allies in World War II to identify airplanes as friend or foe. Transponders are still used by military and commercial aircraft to this day.
Mario Cardullo's U.S. Patent 3,713,148 in 1973 was the first true ancestor of modern RFID; a passive radio transponder with memory. The initial device was passive, powered by the interrogating signal, and was demonstrated in 1971 to the New York Port Authority and other potential users and consisted of a transponder with 16 bit memory for use as a toll device. The basic Cardullo patent covers the use of RF, sound and light as transmission medium. The original business plan presented to investors in 1969 showed uses in transportation (automotive vehicle identification, automatic toll system, electronic license plate, electronic manifest, vehicle routing, vehicle performance monitoring), banking (electronic check book, electronic credit card), security (personnel identification, automatic gates, surveillance) and medical (identification, patient history). A very early demonstration of reflected power (modulated backscatter) RFID tags, both passive and semi-passive, was done by Steven Depp, Alfred Koelle and Robert Freyman at the Los Alamos Scientific Laboratory in 1973[3]. The portable system operated at 915 MHz and used 12 bit tags. This technique is used by the majority of today's UHF and microwave RFID tags. The first patent to be associated with the abbreviation RFID was granted to Charles Walton in 1983 (U.S. Patent 4,384,288). RFID tagsRFID tags come in three general varieties: passive, active, or semi-passive (also known as battery-assisted). Passive tags require no internal power source, thus being pure passive devices (they are only active when a reader is nearby to power them), whereas semi-passive and active tags require a power source, usually a small battery. 
To communicate, tags respond to queries generating signals that must not create interference with the readers, as arriving signals can be very weak and must be told apart. Besides backscattering, load modulation techniques can be used to manipulate the reader's field. Typically, backscatter is used in the far field, whereas load modulation applies in the nearfield, within a few wavelengths from the reader. PassivePassive RFID tags have no internal power supply. The minute electrical current is induced in the antenna by the incoming radio frequency signal,it provides just enough power for the CMOS integrated circuit in the tag to power up and transmit a response. Most passive tags signal by backscattering the carrier wave from the reader. This means that the antenna has to be designed to both collect power from the incoming signal and also to transmit the outbound backscatter signal. The response of a passive RFID tag is not necessarily just an ID number; the tag chip can contain non-volatile, possibly writable EEPROM for storing data. Passive tags have practical read distances ranging from about 10 cm (4 in.) (ISO 14443) up to a few meters (Electronic Product Code (EPC) and ISO 18000-6), depending on the chosen radio frequency and antenna design/size. Due to their simplicity in design they are also suitable for manufacture with a printing process for the antennas. The lack of an onboard power supply means that the device can be quite small: commercially available products exist that can be embedded in a sticker, or under the skin in the case of low frequency RFID tags. In 2007, the Danish Company RFIDsec developed a passive RFID with privacy enhancing technologies built-in including built-in firewall access controls, communication encryption and a silent mode ensuring that the consumer at point of sales can get exclusive control of the key to control the RFID. The RFID will not respond unless the consumer authorizes it, the consumer can validate presence of a specific RFID without leaking identifiers and therefore the consumer can make use of the RFID without being trackable or otherwise leak information that represents a threat to consumer privacy. In 2006, Hitachi, Ltd. developed a passive device called the µ-Chip measuring 0.15×0.15 mm (not including the antenna), and thinner than a sheet of paper (7.5 micrometers).[6][7] Silicon-on-Insulator (SOI) technology is used to achieve this level of integration. The Hitachi µ-Chip can wirelessly transmit a 128-bit unique ID number which is hard coded into the chip as part of the manufacturing process. The unique ID in the chip cannot be altered, providing a high level of authenticity to the chip and ultimately to the items the chip may be permanently attached or embedded into. The Hitachi µ-Chip has a typical maximum read range of 30 cm (1 foot). In February 2007 Hitachi unveiled an even smaller RFID device measuring 0.05×0.05 mm, and thin enough to be embedded in a sheet of paper.[8] The new chips can store as much data as the older µ-chips, and the data contained on them can be extracted from as far away as a few hundred metres. The ongoing problems with all RFIDs is that they need an external antenna which is 80 times bigger than the chip in the best version thus far developed. Further, the present costs of manufacturing the inlays for tags has inhibited broader adoption. As silicon prices are reduced and new more economic methods for manufacturing inlays and tags are perfected in the industry, broader adoption and item level tagging along with economies of scale production scenarios; it is expected to make RFID both innocuous and commonplace much like Barcodes are presently. Alien Technology's Fluidic Self Assembly and HiSam machines, Smartcode's Flexible Area Synchronized Transfer (FAST) and Symbol Technologies' PICA process are alleged to potentially further reduce tag costs by massively parallel production. Alien Technology and SmartCode are currently using the processes to manufacture tags while Symbol Technologies' PICA process is still in the development phase. Symbol was acquired by Motorola in 2006. Motorola however has since made agreements with Avery Dennison for supply of tags, meaning their own Tag production and PICA process may have been abandoned.[9] Alternative methods of production such as FAST, FSA, HiSam and possibly PICA could potentially reduce tag costs dramatically, and due to volume capacities achievable, in turn be able to also drive the economies of scale models for various Silicon fabricators as well. Some passive RFID vendors believe that Industry benchmarks for tag costs can be achieved eventually as new low cost volume production systems are implemented more broadly. (For example, see [3]) Non-silicon tags made from polymer semiconductors are currently being developed by several companies globally. Simple laboratory printed polymer tags operating at 13.56 MHz were demonstrated in 2005 by both PolyIC (Germany) and Philips (The Netherlands). If successfully commercialized, polymer tags will be roll-printable, like a magazine, and much less expensive than silicon-based tags. The end game for most item-level tagging over the next few decades may be that RFID tags will be wholly printed – the same way a barcode is today – and be virtually free, like a barcode. However, substantial technical and economic hurdles must be surmounted to accomplish such an end: hundreds of billions of dollars have been invested over the last three decades in silicon processing, resulting in a per-feature cost which is actually less than that of conventional printing. ActiveUnlike passive RFID tags, active RFID tags have their own internal power source, which is used to power the integrated circuits and broadcast the signal to the reader. Active tags are typically much more reliable (i.e. fewer errors) than passive tags due to the ability for active tags to conduct a "session" with a reader. Active tags, due to their onboard power supply, also transmit at higher power levels than passive tags, allowing them to be more effective in "RF challenged" environments like water (including humans/cattle, which are mostly water), metal (shipping containers, vehicles), or at longer distances, generating strong responses from weak requests (as opposed to passive tags, which work the other way around). In turn, they are generally bigger and more expensive to manufacture, and their potential shelf life is much shorter. Many active tags today have practical ranges of hundreds of meters, and a battery life of up to 10 years. Some active RFID tags include sensors such as temperature logging which have been used to monitor the temperature of perishable goods like fresh produce or certain pharmaceutical products. Other sensors that have been married with active RFID include humidity, shock/vibration, light, radiation, temperature, and atmospherics like ethylene. Active tags typically have much longer range (approximately 500 m/1500 feet) and larger memories than passive tags, as well as the ability to store additional information sent by the transceiver. The United States Department of Defense has successfully used active tags to reduce logistics costs and improve supply chain visibility for more than 15 years. Semi-passiveSemi-passive tags are similar to active tags in that they have their own power source, but the battery only powers the microchip and does not broadcast a signal. The RF energy is reflected back to the reader like a passive tag. An alternative use for the battery is to store energy from the reader to emit a response in the future, usually by means of backscattering. The battery-assisted receive circuitry of semi-passive tags lead to greater sensitivity than passive tags, typically 100 times more. The enhanced sensitivity can be leveraged as increased range (by a factor 10) and/or as enhanced read reliability (by one standard deviation). The enhanced sensitivity of semi-passive tags place higher demands on the reader, because an already weak signal is backscattered to the reader. For passive tags, the reader-to-tag link usually fails first. For semi-passive tags, the reverse (tag-to-reader) link usually fails first. Semi-passive tags have three main advantages 1) Greater sensitivity than passive tags 2) Better battery life than active tags. 3) Can perform active functions (such as temperature logging) under its own power, even when no reader is present. Antenna typesThe antenna used for an RFID tag is affected by the intended application and the frequency of operation. Low-frequency (LF) passive tags are normally inductively coupled, and because the voltage induced is proportional to frequency, many coil turns are needed to produce enough voltage to operate an integrated circuit. Compact LF tags, like glass-encapsulated tags used in animal and human identification, use a multilayer coil (3 layers of 100–150 turns each) wrapped around a ferrite core. At 13.56 MHz (High frequency or HF), a planar spiral with 5–7 turns over a credit-card-sized form factor can be used to provide ranges of tens of centimeters. These coils are less costly to produce than LF coils, since they can be made using lithographic techniques rather than by wire winding, but two metal layers and an insulator layer are needed to allow for the crossover connection from the outermost layer to the inside of the spiral where the integrated circuit and resonance capacitor are located. Ultra-high frequency (UHF) and microwave passive tags are usually radiatively-coupled to the reader antenna and can employ conventional dipole-like antennas. Only one metal layer is required, reducing cost of manufacturing. Dipole antennas, however, are a poor match to the high and slightly capacitive input impedance of a typical integrated circuit. Folded dipoles, or short loops acting as inductive matching structures, are often employed to improve power delivery to the IC. Half-wave dipoles (16 cm at 900 MHz) are too big for many applications; for example, tags embedded in labels must be less than 100 mm (4 inches) in extent. To reduce the length of the antenna, antennas can be bent or meandered, and capacitive tip-loading or bowtie-like broadband structures are also used. Compact antennas usually have gain less than that of a dipole — that is, less than 2 dBi — and can be regarded as isotropic in the plane perpendicular to their axis. Dipoles couple to radiation polarized along their axes, so the visibility of a tag with a simple dipole-like antenna is orientation-dependent. Tags with two orthogonal or nearly-orthogonal antennas, often known as dual-dipole tags, are much less dependent on orientation and polarization of the reader antenna, but are larger and more expensive than single-dipole tags. Patch antennas are used to provide service in close proximity to metal surfaces, but a structure with good bandwidth is 3–6 mm thick, and the need to provide a ground layer and ground connection increases cost relative to simpler single-layer structures. HF and UHF tag antennas are usually fabricated from copper or aluminum. Conductive inks have seen some use in tag antennas but have encountered problems with IC adhesion and environmental stability. Tag attachmentThere are three different kinds of RFID tags based on their attachment with identified objects, i.e. attachable, implantable and insertion tags [10]. In addition to these conventional RFID tags, Eastman Kodak Company has filed two patent applications for monitoring ingestion of medicine comprises forming a digestible RFID tag[11]. Tagging positionsRFID tagging positions can influence the performance of air interface UHF RFID passive tags and related to the position where RFID tags are embedded, attached, injected or digested. In many cases, optimum power from RFID reader is not required to operate passive tags. However, in cases where the Effective Radiated Power (ERP) level and distance between reader and tags are fixed, such as in manufacturing setting, it is important to know the location in a tagged object where a passive tag can operate optimally. R-Spot or Resonance Spot, L-Spot or Live Spot and D-Spot or Dead Spot are defined to specify the location of RFID tags in a tagged object, where the tags can still receive power from a reader within specified ERP level and distance [12]. Tag environmentsThe proposed ubiquity of RFID tags means that readers may need to select which tags to read among many potential candidates, or may wish to probe surrounding devices to perform inventory checks or, in case the tags are associated to sensors and capable of keeping their values, question them for environmental conditions. If a reader intends to work with a collection of tags, it needs to either discover all devices within an area to iterate over them afterwards, or use collision avoidance protocols. 
In order to read tag data, readers use a tree-walking singulation algorithm, resolving possible collisions and processing responses one by one. Blocker tags may be used to prevent readers from accessing tags within an area without killing surrounding tags by means of suicide commands. These tags masquerade as valid tags but have some special properties: in particular, they may possess any identification code, and may deterministically respond to all reader queries, thus rendering them useless and securing the environment. Besides this, tags may be promiscuous, attending all requests alike, or secure, which requires authentication and control of typical password management and secure key distribution issues. A tag may as well be prepared to be activated or deactivated in response to specific reader commands. Readers that are in charge of the tags of an area may operate in autonomous mode (as opposed to interactive mode). When in this mode, a reader periodically locates all tags in its operating range, and keeps a presence list with a persist time and some control information. When an entry expires, it is removed from the list. Frequently, a distributed application requires both types of tags: passive tags are incapable of continuous monitoring and perform tasks on demand when accessed by readers. They are useful when activities are regular and well defined, and requirements for data storage and security are limited; when accesses are frequent, continuous or unpredictable, there are time constraints to meet or data processing (internal searches, for instance) to perform, active tags may be preferred. Current uses
PassportsRFID tags are being used in passports issued by many countries. The first RFID passports ("E-passport") were issued by Malaysia in 1998. In addition to information also contained on the visual data page of the passport, Malaysian e-passports record the travel history (time, date, and place) of entries and exits from the country. Standards for RFID passports are determined by the International Civil Aviation Organization (ICAO), and are contained in ICAO Document 9303, Part 1, Volumes 1 and 2 (6th edition, 2006). ICAO refers to the ISO 14443 RFID chips in e-passports as "contactless integrated circuits". ICAO standards provide for e-passports to be identifiable by a standard e-passport logo on the front cover. In 2006, RFID tags were included in new US passports. The US produced 10 million passports in 2005, and it has been estimated that 13 million will be produced in 2006. The chips will store the same information that is printed within the passport and will also include a digital picture of the owner. The passports will incorporate a thin metal lining to make it more difficult for unauthorized readers to "skim" information when the passport is closed. Transportation payments
Product tracking
Automotive
Animal identification
RFID in inventory systemsAn advanced automatic identification technology such as the Auto-ID system based on the Radio Frequency Identification (RFID) technology has two values for inventory systems. First, the visibility provided by this technology allows an accurate knowledge on the inventory level by eliminating the discrepancy between inventory record and physical inventory. In an academic study[14] performed at Wal-Mart, RFID reduced Out of Stocks by 30 percent for products selling between 0.1 and 15 units a day. Second, the RFID technology can prevent or reduce the sources of errors. Benefits of using RFID include the reduction of labour costs, the simplification of business processes and the reduction of inventory inaccuracies.
Wal-Mart and the United States Department of Defense have published requirements that their vendors place RFID tags on all shipments to improve supply chain management. Due to the size of these two organizations, their RFID mandates impact thousands of companies worldwide. The deadlines have been extended several times because many vendors face significant difficulties implementing RFID systems. In practice, the successful read rates currently run only 80%, due to radio wave attenuation caused by the products and packaging. In time it is expected that even small companies will be able to place RFID tags on their outbound shipments. Since January, 2005, Wal-Mart has required its top 100 suppliers to apply RFID labels to all shipments. To meet this requirement, vendors use RFID printer/encoders to label cases and pallets that require EPC tags for Wal-Mart. These smart labels are produced by embedding RFID inlays inside the label material, and then printing bar code and other visible information on the surface of the label. Human implants
Implantable RFID chips designed for animal tagging are now being used in humans. An early experiment with RFID implants was conducted by British professor of cybernetics Kevin Warwick, who implanted a chip in his arm in 1998. Night clubs in Barcelona, Spain and in Rotterdam, The Netherlands, use an implantable chip to identify their VIP customers, who in turn use it to pay for drinks.[15] In 2004, the Mexican Attorney General's office implanted 18 of its staff members with the Verichip to control access to a secure data room. (This number has been variously mis-reported as 160 or 180 staff members.[16] [17]) Security experts are warned against using RFID for authenticating people due to the risk of identity theft. For instance a man-in-the-middle attack would make it possible for an attacker to steal the identity of a person in real-time. Due to the resource-constraints of RFIDs it is virtually impossible to protect against such attack models as this would require complex distance-binding protocols. RFID in librariesAmong the many uses of RFID technologies is its deployment in libraries. This technology has slowly begun to replace the traditional barcodes on library items (books, CDs, DVDs, etc.). However, the RFID tag can contain identifying information, such as a book’s title or material type, without having to be pointed to a separate database (but this is rare in North America). The information is read by an RFID reader, which replaces the standard barcode reader commonly found at a library’s circulation desk. The RFID tag found on library materials typically measures 50 mm X 50 mm in North America and 50 mm x 75 mm in Europe, and can also act as a security device, taking the place of the more traditional electromagnetic security strip.[18] While there is some debate as to when and where RFID in libraries first began, it was first proposed in the late 1990s as a technology that would enhance workflow in the library setting. Rockefeller University in New York may have been the first academic library in the United States to utilize this technology, whereas Farmington Community Library may have been the first public institution, both of which began using RFID in 1999. Worldwide, the United States utilizes RFID in libraries more than any other nation, followed by the United Kingdom and Japan. It is estimated that over 30 million library items worldwide now contain RFID tags, including some in the Vatican Library in Rome.[19] RFID has many applications in libraries that can be highly beneficial, particularly for circulation staff. Since RFID tags can be read through an item, there is no need to open a book cover or DVD case to scan an item. This would help alleviate injuries such as repetitive strain injury that can occur over many years. Since RFID tags can also be read while an item is in motion, using RFID readers to check-in returned items while on a conveyor belt reduces staff time. Furthermore, inventories could be done on a whole shelf of materials within seconds, without a book ever having to be taken off the shelf.[20]. In Umeå, Sweden, it is being used to assist visually impaired people in borrowing audiobooks[21]. In Malaysia, Smart Shelves are used to pinpoint the exact location of books in Multimedia University Library, Cyberjaya[22]. However, this technology remains cost prohibitive for many smaller libraries, and the conversion time has been estimated at 11 months for an average size library. With RFID taking a large burden off staff, it has also been shown to produce a threat to staff that their job duties have been replaced by technology,[19] but the threat is not realized in North America where recent surveys have not returned a single library that cut staff because of adding RFID. In fact, library budgets are being reduced for personnel and increased for infrastructure, making it necessary for libraries to add automation to compensate for the reduced staff size. A concern surrounding RFID in libraries that has received considerable publicity is the issue of privacy. Because RFID tags can in theory be scanned and read from over 350 feet in distance, and because RFID utilizes an assortment of frequencies, there is a legitimate concern over whether sensitive information could be collected from an unwilling source. However, advocates of RFID’s use in libraries will point out that library RFID tags do not contain any patron information,[23] and that the tags used in the majority of libraries use a frequency only readable from approximately ten feet.[18] There is much yet to be written and discussed on the issue of privacy and RFID, but it is clear that vendors need to be aware of this issue and develop improved technologies for secure RFID transactions. Schools and UniversitiesSchool authorities in the Japanese city of Osaka are now chipping children's clothing, back packs, and student ids in a primary school.[24] A school in Doncaster, England is piloting a monitoring system designed to keep tabs on pupils by tracking radio chips in their uniforms.[25] Other
Potential usesReplacing barcodesRFID tags are often envisioned as a replacement for UPC or EAN barcodes, having a number of important advantages over the older barcode technology. They may not ever completely replace barcodes, due in part to their higher cost and in other part to the advantage of more than one independent data source on the same object. The new EPC, along with several other schemes, is widely available at reasonable cost. The storage of data associated with tracking items will require many terabytes on all levels. Filtering and categorizing RFID data is needed in order to create useful information. It is likely that goods will be tracked preferably by the pallet using RFID tags, and at package level with Universal Product Code (UPC) or EAN from unique barcodes. The unique identity in any case is a mandatory requirement for RFID tags, despite special choice of the numbering scheme. RFID tag data capacity is big enough that any tag will have a unique code, while current bar codes are limited to a single type code for all instances of a particular product. The uniqueness of RFID tags means that a product may be individually tracked as it moves from location to location, finally ending up in the consumer's hands. This may help companies to combat theft and other forms of product loss. Moreover, the tracing back of products is an important feature that gets well supported with RFID tags containing not just a unique identity of the tag but also the serial number of the object. This may help companies to cope with quality deficiencies and resulting recall campaigns, but also contributes to concern over post-sale tracking and profiling of consumers. It has also been proposed to use RFID for POS store checkout to replace the cashier with an automatic system which needs no barcode scanning. However, this is not likely to be possible without a significant reduction in the cost of current tags and changes in the operational process around POS. There is some research taking place, however, this is some years from reaching fruition. An FDA nominated task force came to the conclusion after studying the various technologies currently commercially available, which could meet the pedigree requirements. Amongst all technologies studied including bar coding, RFID seemed to be the most promising and the committee felt that the pedigree requirement could be met by easily leveraging something that is readily available. (More details see RFID-FDA-Regulations) TelemetryActive RFID tags also have the potential to function as low-cost remote sensors that broadcast telemetry back to a base station. Applications of tagometry data could include sensing of road conditions by implanted beacons, weather reports, and noise level monitoring. Patient identificationIn July 2004, the Food and Drug Administration issued a ruling that essentially begins a final review process that will determine whether hospitals can use RFID systems to identify patients and/or permit relevant hospital staff to access medical records. Since then, a number of U.S. hospitals have begun implanting patients with RFID tags and using RFID systems, more generally, for workflow and inventory management.[30] The use of RFID to prevent mixups between sperm and ova in IVF clinics is also being considered [4]. In October 2004, the FDA approved USA's first RFID chips that can be implanted in humans. The 134 kHz RFID chips, from VeriChip Corp., a subsidiary of Applied Digital Solutions Inc., can incorporate personal medical information and could save lives and limit injuries from errors in medical treatments, according to the company. The FDA approval was disclosed during a conference call with investors. Shortly after the approval, authors and anti-RFID activists Katherine Albrecht and Liz McIntyre discovered a warning letter from the FDA that spelled out serious health risks associated with the VeriChip. According to the FDA, these include "adverse tissue reaction", "migration of the implanted transponder", "failure of implanted transponder", "electrical hazards" and "magnetic resonance imaging [MRI] incompatibility." In 2007 John Wiley & Sons published a guide to RFID use in the book RFID Applied (ISBN 978-0-471-79365-6) Regulation and standardizationThere is no global public body that governs the frequencies used for RFID. In principle, every country can set its own rules for this. The main bodies governing frequency allocation for RFID are:
Low-frequency (LF: 125 – 134.2 kHz and 140 – 148.5 kHz) and high-frequency (HF: 13.56 MHz) RFID tags can be used globally without a license. Ultra-high-frequency (UHF: 868 MHz-928 MHz) cannot be used globally as there is no single global standard. In North America, UHF can be used unlicensed for 902 – 928 MHz (±13 MHz from the 915 MHz center frequency), but restrictions exist for transmission power. In Europe, RFID and other low-power radio applications are regulated by ETSI recommendations EN 300 220 and EN 302 208, and ERO recommendation 70 03, allowing RFID operation with somewhat complex band restrictions from 865–868 MHz. Readers are required to monitor a channel before transmitting ("Listen Before Talk"); this requirement has led to some restrictions on performance, the resolution of which is a subject of current research. The North American UHF standard is not accepted in France as it interferes with its military bands. For China and Japan, there is no regulation for the use of UHF. Each application for UHF in these countries needs a site license, which needs to be applied for at the local authorities, and can be revoked. For Australia and New Zealand, 918 – 926 MHz are unlicensed, but restrictions exist for transmission power. These frequencies are known as the ISM bands (Industrial Scientific and Medical bands). The return signal of the tag may still cause interference for other radio users Some standards that have been made regarding RFID technology include:
EPC Gen2EPC Gen2 is short for EPCglobal UHF Class 1 Generation 2. EPCglobal (a joint venture between GS1 and GS1 US) is working on international standards for the use of mostly passive RFID and the EPC in the identification of many items in the supply chain for companies worldwide. One of the missions of EPCglobal was to simplify the Babel of protocols prevalent in the RFID world in the 1990s. Two tag air interfaces (the protocol for exchanging information between a tag and a reader) were defined (but not ratified) by EPCglobal prior to 2003. These protocols, commonly known as Class 0 and Class 1, saw significant commercial implementation in 2002–2005. In 2004 the Hardware Action Group created a new protocol, the Class 1 Generation 2 interface, which addressed a number of problems that had been experienced with Class 0 and Class 1 tags. The EPC Gen2 standard was approved in December 2004, and is likely to form the backbone of passive RFID tag standards moving forward. This was approved after a contention from Intermec that the standard may infringe a number of their RFID related patents. It was decided that the standard itself did not infringe their patents, but it may be necessary to pay royalties to Intermec if the tag were to be read in a particular manner. The EPC Gen2 standard was adopted with minor modifications as ISO 18000-6C in 2006. The lowest cost of Gen2 EPC inlay is offered by SmartCode at a price of 5 cents apiece in volumes of 100 million or more[31]. Nevertheless, further conversion (including additional label stock or encapsulation processing/insertion and freight costs to a given facility or DC) and of the inlays into usable RFID labels and the design of current Gen 2 protocol standard will increase the total end-cost, especially with the added security feature extensions for RFID Supply Chain item-level tagging. Problems and ConcernsGlobal standardizationThe frequencies used for RFID in the USA are currently incompatible with those of Europe or Japan. Furthermore, no emerging standard has yet become as universal as the barcode.[32] Security concernsA primary security concern surrounding technology is the illicit tracking of RFID tags. Tags which are world-readable pose a risk to both personal location privacy and corporate/military security. Such concerns have been raised with respect to the United States Department of Defense's recent adoption of RFID tags for supply chain management.[33] More generally, privacy organizations have expressed concerns in the context of ongoing efforts to embed electronic product code (EPC) RFID tags in consumer products. EPCglobal Network, by design, is also susceptible to DoS attacks. Using similar mechanism with DNS in resolving EPC data requests, the ONS Root servers become vulnerable to DoS attacks. Any organisation planning to embark on EPCglobal Network will cringe finding out that the EPCglobal Network infrastructure inherits security weaknesses similar to DNS'[34]. A second class of defense uses cryptography to prevent tag cloning. Some tags use a form of "rolling code" scheme, wherein the tag identifier information changes after each scan, thus reducing the usefulness of observed responses. More sophisticated devices engage in Challenge-response authentications where the tag interacts with the reader. In these protocols, secret tag information is never sent over the insecure communication channel between tag and reader. Rather, the reader issues a challenge to the tag, which responds with a result computed using a cryptographic circuit keyed with some secret value. Such protocols may be based on symmetric or public key cryptography. Cryptographically-enabled tags typically have dramatically higher cost and power requirements than simpler equivalents, and as a result, deployment of these tags is much more limited. This cost/power limitation has led some manufacturers to implement cryptographic tags using substantially weakened, or proprietary encryption schemes, which do not necessarily resist sophisticated attack. For example, the Exxon-Mobil Speedpass uses a cryptographically-enabled tag manufactured by Texas Instruments, called the Digital Signature Transponder (DST), which incorporates a weak, proprietary encryption scheme to perform a challenge-response protocol. Still other cryptographic protocols attempt to achieve privacy against unauthorized readers, though these protocols are largely in the research stage. One major challenge in securing RFID tags is a shortage of computational resources within the tag. Standard cryptographic techniques require more resources than are available in most low cost RFID devices. RSA Security has patented a prototype device that locally jams RFID signals by interrupting a standard collision avoidance protocol, allowing the user to prevent identification if desired.[35] Various policy measures have also been proposed, such as marking RFID tagged objects with an industry standard label. VirusesArs Technica Reported in March 2006 an RFID buffer overflow bug that could infect airport terminal RFID Databases for baggage, and also Passport databases to obtain confidential information on the passport holder.[36] PassportsIn an effort to make passports more secure, several countries have implemented RFID in passports. However, the encryption on UK chips was broken in under 48 hours.[37] Since that incident, further efforts have allowed researchers to clone passport data while the passport is being mailed to its owner. Where before a criminal had to secretly open and then reseal the envelope, now it can be done without detection, adding some degree of insecurity to the passport system.[38] Protection against RFID interceptionVarious methods can be used to protect against RFID data interception:[39]
RFID shieldingA number of products are available on the market in the US that will allow a concerned carrier of RFID-enabled cards or passports to shield their data. In fact the United States government requires their new employee ID cards to be delivered with an approved shielding sleeve or holder. There are contradicting opinions as to whether aluminum can prevent reading of RFID chips. Some people claim that aluminum shielding, essentially creating a Faraday cage, does work.[40] Others claim that simply wrapping an RFID card in aluminum foil, only makes transmission more difficult, yet is not completely effective at preventing it.[41] Shielding is again a function of the frequency being used. Low-frequency tags, like those used in implantable devices for humans and pets, are relatively resistant to shielding, though thick metal foil will prevent most reads. High frequency tags (13.56 MHz — smart cards and access badges) are more sensitive to shielding and are difficult to read when within a few centimetres of a metal surface. UHF tags (pallets and cartons) are very difficult to read when placed within a few millimetres of a metal surface, although their read range is actually increased when they are spaced 2–4 cm from a metal due to positive reinforcement of the reflected wave and the incident wave at the tag. UHF tags can be successfully shielded from most reads by being placed within an anti-static plastic bag. Cancer riskOn September 8, 2007, veterinary and toxicology studies spanning the last ten years surfaced indicating that RFID chips induced malignant tumors in laboratory animals. The U.S. Food and Drug Administration, the agency that approved the use of the chips in the United States, refused to respond to questions from the media about their awareness of the studies. VeriChip Corp. maintains that the chips are completely safe and that they were unaware of the studies. The studies were somewhat limited in scope, lacking control groups that did not receive chips and failing to test large animals such as dogs, cats, or primates. As a result, most of the studies included cautionary language against making assumptions about the chips causing cancer in humans based on the study results.[42] Controversies
PrivacyHow would you like it if, for instance, one day you realized your underwear was reporting on your whereabouts? — California State Senator Debra Bowen, at a 2003 hearing.[43] The use of RFID technology has engendered considerable controversy and even product boycotts by consumer privacy advocates such as Katherine Albrecht and Liz McIntyre of CASPIAN who refer to RFID tags as "spychips". The two main privacy concerns regarding RFID are:
Most concerns revolve around the fact that RFID tags affixed to products remain functional even after the products have been purchased and taken home and thus can be used for surveillance and other purposes unrelated to their supply chain inventory functions.[44] The concerns raised by the above may be addressed in part by use of the Clipped Tag. The Clipped Tag is an RFID tag designed to increase consumer privacy. The Clipped Tag has been suggested by IBM researchers Paul Moskowitz and Guenter Karjoth. After the point of sale, a consumer may tear off a portion of the tag. This allows the transformation of a long-range tag into a proximity tag that still may be read, but only at short range – less than a few inches or centimeters. The modification of the tag may be confirmed visually. The tag may still be used later for returns, recalls, or recycling. However, read range is both a function of the reader and the tag itself. Improvements in technology may increase read ranges for tags. Having readers very close to the tags makes short range tags readable. Generally, the read range of a tag is limited to the distance from the reader over which the tag can draw enough energy from the reader field to power the tag. Tags may be read at longer ranges than they are designed for by increasing reader power. The limit on read distance then becomes the signal-to-noise ratio of the signal reflected from the tag back to the reader. Increased reader power may increase read ranges by a factor of three, but cannot turn a proximity tag into a long-range tag. Another privacy issue is due to RFID's support for a singulation (anti-collision) protocol. This is the means by which a reader enumerates all the tags responding to it without them mutually interfering. The structure of some collision-resolution (Medium Access Control) protocols is such that all but the last bit of each tag's serial number can be deduced by passively eavesdropping on just the reader's part of the protocol. Because of this, whenever the relevant types of RFID tags are near to readers, the distance at which a tag's signal can be eavesdropped is irrelevant; what counts is the distance at which the much more powerful reader can be received. Just how far this can be depends on the type of the reader, but in the extreme case some readers have a maximum power output of 4 W, enabling signals to be received from tens of kilometres away. However, more recent UHF tags employing the EPCglobal Gen 2 (ISO 18000-6C) protocol, which is a slotted-Aloha scheme in which the reader never transmits the tag identifying information, are not subject to this particular attack. Technical note: the anti-collision scheme of ISO 15693 will render this rather implausible. To eavesdrop on the reader part of the protocol – and gather the 63 least significant bits of a uid – would require the reader to send a mask value of 63 bits. This can only happen when the reader detects a collision up to the 63rd bit. In other words: One can eavesdrop on the transmitted mask-value of the reader, but for the reader to transmit a 63 bit mask-value requires two tags with identical least significant 63 bits. The probability of this happening must be near zero. I.e. the eavesdropper needs two virtually identical tags to be read at the same time by the reader in question. In any discussion of eavesdropping and skimming, it is important to make a distinction between inductively-coupled and radiatively-coupled tags. Protocols like ISO 15693 use 13.5 |
