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An RFID tag (also referred to as a transponder) is an electronic device that communicates with RFID readers. An RFID tag can function as a beacon or it can be used to convey information such as an identifier.[1]


RFID tag

RFID tag

An RFID tag consists of (1) a small integrated circuit chip[2] (2) attached to a miniature antennae,[3] which is capable of transmitting a unique serial number to (3) a mobile or stationary reader[4] in response to a query. A fourth important part of any RFID system is the database[5] where information about tagged objects is stored.

Every RFID tag has a unique identification number. The identification number includes not only the traditional information contained in a printed barcode (indicating manufacturer and product type), but also a unique serial number for that tag, meaning that each product or item will be uniquely identified.[6]

Tag characteristics[]

The market for RFID tags includes numerous different types of tags, which differ greatly in their cost, size, performance, and security mechanisms. Even when tags are designed to comply with a particular standard, they are often further customized to meet the requirements of specific applications. Understanding the major tag characteristics can help those responsible for RFID systems identify the tag characteristics required in their environments and applications.

Major characteristics of tags include:

Tags can be attached to items using an adhesive or can be embedded within the item. The primary concern when a tag is attached to an item is how easily it might be detached, whether accidentally or maliciously. Tags attached to items also are more vulnerable to harsh environmental conditions such as dust, debris, humidity, precipitation, and extreme temperatures. However, the vulnerability is intentional in some cases. For example, RFID tags known as "frangible tags" allow users to deactivate tags by tearing the tag’s antenna from its circuitry. Tags that are embedded in objects (e.g., smart cards, animal tissue, plastic housing) are less vulnerable to tampering and environmental conditions.

Types of RFID tags[]

There are three types of RFID tags.

  • Passive — Most RFID tags are passive. They do not contain a power source and obtain the power needed to operate from the query signal itself. An RFID reader must first query a passive tag, sending electromagnetic waves that form a magnetic field when they “couple” with the antenna on the RFID tag. Consistent with any applicable authorization, authentication, and encryption, the tag will then respond to the reader, sending via radio waves the data stored on it. Currently, depending on the size of the antenna and the frequency, passive tags can be read, at least theoretically, from up to thirty feet away.
  • Semi-passive — A semi-passive tag, like a passive tag, does not initiate communication with readers, but they do have batteries. This onboard power is used to operate the circuitry on the chip, storing information such as ambient temperature. Semi-passive tags can be combined, for example, with sensors to create “smart dust” — tiny wireless sensors that can monitor environmental factors.
  • Active — Active tags can initiate communication and typically have onboard power. They can communicate the longest distances — 100 or more feet. Currently, active tags typically cost $20 or more. A familiar application of active tags is for automatic toll payment systems that allow cars bearing active tags to use express lanes that do not require drivers to stop and pay.

RFID proponents believe that the ability of these systems to deliver precise and accurate data about tagged items will improve efficiency and bring other benefits to businesses and consumers alike. While these developments may offer significant benefits for industry and consumers, some applications have raised privacy concerns. The capacity to encode unique identifiers at the individual item level may have revolutionized thinking about inventory management, but it has also raised fears that this technology might be used to track individual products out of the store and into consumers’ homes or otherwise monitor individual consumer behaviors.

RFID system components[]

RFID systems can be very complex, and implementations vary greatly across industries and sectors. For purposes of discussion, an RFID system is composed of up to three subsystems:

Every RFID system contains an RF subsystem, and most RFID systems also contain an enterprise subsystem. The characteristics of RFID enterprise and inter-enterprise subsystems are very similar to those of any networked IT system in terms of the types of computers that reside on them, the protocols they support, and the security issues they encounter.

Security concerns[]

While RFID has numerous advantages over bar code technology, it also raises security concerns. Two types of risks are associated with the security of RFID tags. The first is the possibility of DoS attacks against RFID readers that would render them incapable of tracking assets and inventory or reading product prices in point-of-sale applications. Criminals might use such an attack to make readers inoperable in order to hide criminal activity.

The second and more serious type of risk involves the basic security functions associated with RFID tags and readers, such as encryption of information and authentication of RFID communication signals. Inadequate RFID security could result in unauthorized eavesdropping on communication signals, unauthorized tracking of assets, or spoofing of readers by intentionally misleading tags. This could lead to unauthorized access to sensitive information about individuals or supply chains, price tampering, counterfeiting, theft, and other illegal activity.

Privacy concerns[]

Consumer advocates have voiced concerns about the potential impact of other RFID applications on consumer privacy. According to them, such concerns may arise when consumers interact more directly with tags and readers, particularly in the context of item-level tagging of retail goods.

These concerns implicate issues specific to RFID technology as well as more general privacy issues. RFID’s unique or distinguishing characteristics may jeopardize consumer privacy. First, the “bit capacity” of Electronic Product Codes (“EPCs”) may enable the assignment of individual identifiers to tagged objects. RFID’s potential to identify items uniquely facilitates the collection of more — and more accurate — data.[7]

Other troublesome features of RFID relate to the devices’ physical attributes. The small size of tags and readers enables them to be hidden from consumers. If a long read-range is not required, scanners can be smaller than a U.S. quarter. The shrinking dimensions of RFID tags can facilitate their unobtrusive integration into consumer goods. RFID devices can communicate with one another through materials, without line-of-sight, and at some distance. These technical characteristics distinguish RFID from bar codes, which in order to be read must be visible on the outside of product packaging. These characteristics can allow surreptitious scanning to gather information about the products consumers wear or carry. When tags can be accessed by multiple readers, it raises the specter of unfettered third-party surveillance.

The combination of these factors may weaken consumers’ ability to protect themselves from in-store tracking and surreptitious monitoring in public places, at work, and even at home. RFIDs have the potential to facilitate consumer tracking, by linking personally identifiable information in databases to the unique numbers on RFID tags. A retailer could associate purchaser data with the uniquely identified product an individual buys.

This practice would be similar to what retailers can currently do with customer loyalty cards or credit cards. However, RFIDs may poses even greater threats to consumer privacy because of the enhanced level of information it provides about each tagged item. A tagged item carried by a consumer out of a store could be read covertly, and what it communicates could be more than just the presence of a particular item. If linked to purchase data, the identification of a particular product could also identify the individual who bought that item.

This potential raises another privacy concern: consumer profiling. By tracking the movement of tagged goods and the people associated with them, more information can be gathered about the activities of those individuals. That in turn could make it easier to predict the behavior of others who buy the same items, even without monitoring them. Another concern relates to RFID’s facilitation of “customer relationship management,” whereby retailers can customize pricing and service based on a consumer’s potential profitability.

If RFID tags were embedded in customer loyalty cards, consumers could be identified as soon as they entered the store that issued the card. This could result in targeted marketing or customer service directed at the consumer, depending on his or her purchase history or other information linked to the loyalty card.

Even if and when item-level tagging is adopted on a widespread basis, some critics dispute that consumer privacy would be jeopardized as a result. They asserted that RFID’s technological limitations will prevent its surreptitious use. For example, reading an RFID tag from a significant distance currently requires use of a sizable antenna and significant energy. Another argument focuses on how cost factors will continue to slow retailers’ adoption of RFID, limiting the sophistication and proliferation of readers on the store floor. Others argue that no business case exists for linking data collected via RFID to personally identifiable information about consumers, so fears about this potential are misplaced. In addition, some critics addressed the emergence of a variety of technological protocols and products, such as encryption and blocker tags,[8] that may offer a means to address privacy concerns associated with these devices.


  1. Guidelines for Securing Radio Frequency Identification (RFID) Systems, Glossary, at B-3.
  2. The chip, usually made of silicon, contains information about the item to which it is attached. Chips used by retailers and manufacturers to identify consumer goods may contain an Electronic Product Code (“EPC”). The EPC is the RFID equivalent of the familiar Universal Product Code (“UPC”), or bar code, currently imprinted on many products. Bar codes must be optically scanned, and contain only generic product information. By contrast, EPC chips are encrypted with a unique product code that identifies the individual product to which it is attached, and can be read using radio frequency (RF). These codes contain the type of data that product manufacturers and retailers will use to track the authenticity and location of goods throughout the supply chain. An RFID chip may also contain information other than an EPC, such as biometric data (a digitized image of a fingerprint or photograph, for example). In addition, some chips may not be loaded with information uniquely identifying the tagged object at all; so-called “electronic article surveillance systems” (“EAS”) may utilize radio frequency communication to combat shoplifting, but not to uniquely identify individual items.
  3. The antenna attached to the chip is responsible for transmitting information from the chip to the reader, using radio waves. Generally, the bigger the antenna, the longer the read range. The chip and antenna combination is referred to as a transponder or, more commonly, as a tag.
  4. The reader, or scanning device, also has its own antenna, which it uses to communicate with the tag. Readers vary in size, weight, and power, and may be mobile or stationary. Although anyone with access to the proper reader can scan an RFID tag, RFID systems can employ authentication and encryption to prevent unauthorized reading of data. “Reading” tags refers to the communication between the tag and reader via radio waves operating at a certain frequency. In contrast to bar codes, one of RFID’s principal distinctions is tags and readers can communicate with each other without being in each other’s line-of-sight. Therefore, a reader can scan a tag without physically “seeing” it. Further, RFID readers can process multiple items at one time, resulting in a much-increased (again as compared to UPC codes) “speed of read.”
  5. The database, or other back-end logistics system, stores information about RFID-tagged objects. Access to both a reader and its corresponding database are necessary before information stored on an RFID tag can be obtained and understood. In order to interpret such data, RFID readers must be able to communicate with a database or other computer program.
  6. Thus, for example, in a clothing store, each particular suit jacket, including its style, color, and size, can be identified electronically. In a pharmacy, a druggist can fill a prescription from a bottle bearing an RFID-chipped label confirming the authenticity of its contents. On the highway, cars with RFID tags on their windshields can move swiftly through highway tollbooths, saving time and reducing traffic congestion. At home, pets can be implanted with chips so that lost animals can be identified and returned to their owners more readily. In each case, a reader must scan the tag for the data it contains and then send that information to a database, which interprets the data stored on the tag. The tag, reader, and database are the key components of an RFID system.
  7. For example, using RFID devices to track people (such as students) or their automobiles (as with E-Z Passes) could generate precise and personally identifiable data about their movements and raise privacy concerns.
  8. Blocker tags work by essentially “spammingreaders by confusing them with so many announcements from chips that the reader is effectively overwhelmed.