Key Fob
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Key Fob Definition
A key fob is a small electronic device that allows someone to access or control something without using a traditional key. It sends a wireless signal to a receiver or reader, which checks if the signal is valid before allowing access. Key fobs are commonly used to unlock cars, open doors in offices or apartments, activate security systems, or even for user authentication.
How a Key Fob Works
A key fob sends a short-range wireless signal to a nearby receiver. Inside the key fob are a small electronic chip and an antenna. When a button is pressed or the key fob is brought close to a reader, the device transmits an identifier or code (which often changes) using radio-frequency signals.
The receiver listens for the signal and verifies whether the transmitted code is recognized and authorized. If the code matches what the system expects, access is granted. If it doesn’t match, access is denied, and nothing happens.
Some key fobs are active and use a battery to transmit signals when a button is pressed or when communicating with a nearby system. Others are passive tag-style fobs (such as RFID or NFC) that draw power from the reader’s field when held close. In proximity systems, access can be granted with little or no interaction beyond carrying or tapping the fob.
Types of Key Fobs
- Remote key fob: Uses buttons to send a wireless signal to lock or unlock doors.
- Proximity key fob: Works automatically when it’s close to a reader, without pressing buttons.
- RFID key fob: Requires close contact with a reader and is commonly used for building access.
- NFC key fob: Relies on short-range contactless technology similar to mobile payments.
- Smart key fob: Supports features like keyless entry and push-button start.
- VPN authentication token: In workplace IT, a key fob-style token used for VPN multi-factor authentication is sometimes called a “vpn fob.”
Common Uses of a Key Fob
- Vehicle access: Locks, unlocks, or starts a car without using a physical key.
- Building entry: Grants access to offices, apartments, or secured facilities.
- Workplace security: Identifies employees and controls access to restricted areas.
- Parking systems: Opens gates or records entry and exit in parking facilities.
- Alarm and security systems: Activates or deactivates home or office security systems.
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FAQ
A key fob is a small device that uses wireless signals to help control access, often through a reader or receiver. A smart card is a flat card that presents credentials to a reader, either by tapping it (contactless) or by inserting/swiping it, depending on the system. Both can be used for access control and authentication, but smart cards often also serve as identification badges.
It depends on the technology and system design. Proximity, RFID, and NFC key fobs usually work at very short distances, from a few centimeters up to a few inches. Remote key fobs, such as car remotes, can work from several feet away and sometimes further in open areas, though walls, interference, and battery strength can reduce the range.
Yes, a key fob can be used as an authentication factor because it proves the user has an authorized physical credential. When a reader detects a valid fob ID, the system treats it as a trusted “something you have” and grants access. However, a fob by itself usually confirms you have the credential, not your identity, unless it’s linked to your user account or combined with another factor like a PIN, password, or biometric check.
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