Google 'RFID transponder' and you'll find enough info…
Thanks.
Wikipedia's has an informative page on Radio Frequency Identification. Here are a few tidbits from that page, relevant to my OP:
RFID tags contain electronically-stored information. Passive tags collect energy from a nearby RFID reader's interrogating radio waves. Active tags have a local power source (such as a battery) and may operate hundreds of meters from the RFID reader.
The radio frequency used for credit cards and other smart card readers is 13.56 MHz.
RFID is used in a variety of applications, such as:
- Access management
- Tracking of goods
- Tracking of persons and animals
- Toll collection and contactless payment
- Machine readable travel documents
- Smartdust (for massively distributed sensor networks)
- Airport baggage tracking logistics
- Timing sporting events
- Tracking and billing processes
Countries that insert RFID in passports include Norway (2005),Japan (March 1, 2006),most
EU countries (around 2006),Australia, Hong Kong, the United States (2007),India (June 2008),Serbia (July 2008),Republic of Korea (August 2008),Taiwan (December 2008),Albania (January 2009),The Philippines (August 2009),Republic of Macedonia (2010),Canada (2013) and Israel (2017).
RFID tags included in new US passports will store the same information printed within the passport, and include a digital picture of the owner.
The US Department of State initially stated the chips could only be read from a distance of 10 centimeters (3.9 in),but after widespread criticism and a clear demonstration that special equipment can read the test passports from 10 meters (33 ft) away, the passports were designed (since 2006) to incorporate a thin metal lining to make it more difficult for unauthorized readers to "skim" information when the passport is closed. The department will also implement a PIN number system. Before a passport's tag can be read, this PIN must be entered into an RFID reader. This also enables encryption of communication between the chip and reader. There are many situations in which these protections have been shown to be insufficient, and passports have been cloned based on scans of them while they were being delivered in the mail.
Security concerns
A primary RFID security concern 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 US Department of Defense's recent adoption of RFID tags for supply chain management. More generally, privacy organizations have expressed concerns in the context of ongoing efforts to embed electronic product code (EPC) RFID tags in consumer products.
This is mostly as result of the fact that RFID tags can be read, and legitimate transactions with readers can be eavesdropped, from non-trivial distances. RFID used in access control, payment and eID (e-passport) systems operate at a shorter range than EPC RFID systems but are also vulnerable to skimming and eavesdropping, albeit at shorter distance.
A second method of prevention is by using cryptography. Rolling codes and challenge-response authentication (CRA) are commonly used to foil monitor-repetition of the messages between the tag and reader; as any messages that have been recorded would prove to be unsuccessful on repeat transmission. Rolling codes rely upon the tag's id being changed after each interrogation, while CRA uses software to ask for a cryptographically coded response from the tag. The protocols used during CRA can be symmetric, or may use public key cryptography.
Passports
In an effort to standardize and make it easier to process passports, several countries have implemented RFID in passports, despite security and privacy issues.
The encryption on UK chips was broken in under 48 hours. Since that incident, further efforts have allowed researchers to clone passport data while the passport is being mailed to its owner.
Shielding
In an effort to prevent the passive “skimming” of RFID-enabled cards or passports, the US General Services Administration (GSA) issued a set of test procedures for evaluating electromagnetically opaque sleeves. For shielding products to be in compliance with FIPS-201 guidelines, they must meet or exceed this published standard. Shielding products currently evaluated as FIPS-201 compliant are listed on the website of the US CIO's FIPS-201 Evaluation Program.
The US government requires that when new ID cards are issued, they must 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. Others claim that simply wrapping an RFID card in aluminum foil only makes transmission more difficult and is not completely effective at preventing it.
Shielding effectiveness depends on the frequency being used.
High frequency HighFID tags (13.56 MHz—smart cards and access badges) are sensitive to shielding and are difficult to read when within a few centimeters of a metal surface.
Sorry for the length, see the Wikipedia link for more details.