Key Fob

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What is a Key Fob?

A key fob is a compact, wireless device that operates through radio frequency (RF) communication, infrared signals, or a combination of both to perform remote actions such as locking or unlocking doors and starting vehicles.


This device, typically attached to a keychain for convenience, interacts with a corresponding electronic system to execute commands without physical contact.

Techopedia Explains

There are mainly two types of key fobs that have become staples in our lives: automotive and access control systems. They offer convenience by simplifying operations like entering vehicles or buildings, and they improve security by enabling encrypted signal transmission, which reduces the risk of unauthorized access.

  • Automotive Key Fobs: These are designed for vehicle use, allowing you to remotely lock and unlock your car, activate the alarm, and, in more advanced models, start the engine without inserting a key into the ignition. Automotive key fobs use encrypted RF signals to communicate with the car’s electronic control unit (ECU), ensuring that only the holder of the correct fob can access and operate the vehicle.
  • RFID Fobs for Security Access: Used in security and access control systems, RFID key fobs contain a small chip and antenna that transmit a unique identifier to an RFID reader. Upon recognition, the reader allows or denies entry based on predefined access permissions. These fobs are commonly used in office buildings, residential complexes, and other secure facilities to manage entry without traditional keys. They offer the advantage of easily altering access permissions electronically, eliminating the need to change locks or keys when security needs change.

Key fobs have also integrated advanced technologies like rolling code encryption, which enhances security by generating a new code with each use, making them nearly impossible to duplicate for unauthorized entry.

History of the Key Fob

The key fob has journeyed from being a simple mechanical device to a sophisticated electronic gadget that offers enhanced security and convenience.

Originally, the term “fob” referred to small ornaments attached to a pocket watch chain. It wasn’t until the late 20th century that the term began to be associated with small electronic devices designed for remote control access.

The transition from mechanical keys to the first electronic key fobs began in the 1980s with the automotive industry’s introduction of remote-controlled keyless entry systems.

These early electronic fobs were basic, offering the simple function of locking and unlocking car doors with a press of a button. As technology advanced, additional features like alarm systems, panic buttons, and even remote start functions were added.

Key Fob Development Milestones

  • 1980s: Introduction of remote keyless entry systems in cars.
  • 1990s: Incorporation of rolling code technology, significantly improving security by changing the code each time the fob was used.
  • 2000s: Adoption of RFID technology for access control in buildings and secure facilities.
  • 2010s and beyond: Integration of Near Field Communication (NFC) and Bluetooth technology, enabling key fobs to interact with smartphones and other devices for a broader range of applications.

How a Key Fob Works

Key fobs are a major part of wireless communication systems, allowing remote control over various devices and systems like cars and security gates.

They primarily use two types of technology: Radio Frequency Identification and Bluetooth.

  • RFID: This technology involves communication between the key fob and a corresponding receiver through radio waves. Each key fob is equipped with a unique ID. When a button on the fob is pressed, it sends a signal encoded with this identifier to the receiver, which then verifies the code before performing the requested action, such as unlocking a door.
  • Bluetooth: Some key fobs use Bluetooth technology, especially in smart devices, to communicate with a receiver or a smartphone app. Bluetooth key fobs can offer a range of functionalities, from starting a car to controlling smart home devices, by establishing a secure, wireless connection with the target device.

The communication process between a key fob and its receiver starts when the user presses a button on the fob. This action sends a signal encoded with a specific command (e.g., unlock the door) and a unique identifier to the receiver.

The receiver, equipped to read and authenticate the signal, verifies the identifier and executes the command if the signal is recognized as authorized.

Key Fob Security

Key fobs are becoming more of a part of our daily lives, just as smartphones have. This increase in use also brings about concerns over their security. The big security concern is that of potential vulnerabilities that could be exploited by digital lock pickers.

Potential Security Vulnerabilities

Key fobs, especially those used in cars and for building access, transmit signals that, if intercepted, could be duplicated or manipulated. Techniques such as signal relaying, where a thief captures and extends the signal from a key fob to unlock a car or door without physical possession of the fob, pose significant risks.

Also, older key fobs that do not use rolling codes or encryption can be more easily cloned.

Security Features

To ensure the security of these communications, some (especially more modern) key fobs take advantage of various security tech.

Security Feature Description
Rolling Codes Rolling codes, also known as hopping codes, are a security feature where the key fob generates a new, unique code for each operation.

This system relies on an algorithm shared between the fob and the receiver. After each use, both the key fob and the receiver synchronize to a new code based on the algorithm, making previously used codes obsolete.

This majorly reduces the risk of unauthorized access through code capturing or replay attacks.

Encryption Encryption involves encoding the signal sent from the key fob to the receiver, ensuring that the information can only be understood by the intended recipient.

Even if an intruder intercepts the encrypted signal without the corresponding decryption key, the data remains unintelligible and useless.

Different levels of encryption, from basic to advanced (e.g., AES encryption), are employed based on the required security level.

Frequency Hopping Some key fobs use frequency hopping, a method where the signal transmission between the fob and the receiver alternates across different frequencies.

This makes it more difficult for eavesdroppers to intercept and decode the signal, as they would need to follow the unpredictable changes in frequency.

Biometric Verification Advanced key fobs incorporate biometric verification methods, such as fingerprint recognition, to add a layer of security that is unique to the user.

This feature ensures that even if a key fob is lost or stolen, it cannot be used by unauthorized persons, as the biometric data will not match.

Proximity Sensors Proximity sensors enhance security by enabling the key fob to work only when it is within a specific range of the receiver.

This feature limits the potential for relay attacks, where an attacker uses a device to extend the signal from the key fob to the receiver from a distance.

Best Practices for Securing Your Key Fob

Best Practices for Securing Your Key Fob

Follow these best practices to help mitigate the risks associated with key fob security:

  • Keep Software Updated: Ensure that any associated software, especially for smart key fobs, is kept up to date to benefit from the latest security patches.
  • Use Signal-Blocking Pouches: Store key fobs in signal-blocking (Faraday) pouches when not in use to prevent signal interception.
  • Be Mindful of Where You Store Your Key Fob: Avoid leaving key fobs near doors or windows where signals can be more easily hijacked.
  • Regularly Change Codes: If your system allows, regularly change the codes or pairing of your key fob to prevent unauthorized access from stored signals.

How to Program a Key Fob

The process of programming a key fob can vary greatly depending on the device or vehicle you’re programming it for. Also, the make and model of the device or vehicle is also a factor.

That said, here’s a general guide to help you through the steps. For the most accurate programming method, refer to the manufacturer’s guide of your product.

  1. Gather Necessary Tools: Most programming procedures require no special tools, but some may need a particular device or software provided by the manufacturer. Always check beforehand.
  2. Consult Manufacturer Instructions: Before trying to program your key fob, consult the user manual or manufacturer’s website for specific instructions related to your model. This step is very important as it provides the exact procedure, which varies significantly across different brands and systems.
  3. Enter Programming Mode: Typically, this involves a series of actions like turning the ignition on and off a specific number of times, pressing certain buttons on the fob, or a combination of both. The vehicle may signal entry into programming mode with a sound or light flash.
  4. Perform Programming Sequence: Follow the manufacturer’s specific steps to program the key fob. This often involves pressing and holding buttons on the fob while the vehicle is in programming mode.
  5. Exit Programming Mode: After completing the sequence, ensure you properly exit the programming mode as instructed by the manufacturer. This might involve turning off the ignition or performing a specific action with the key fob.
  6. Test the Key Fob: Always test the key fob to make sure it’s functioning as intended. Try all the buttons to confirm they perform the correct actions.

Again, these are general guidelines, and you should always refer to the user guide of your device or system for exact instructions.

How to Replace the Battery in a Key Fob

When a key fob starts to malfunction, it might be time to replace the battery. Here are a few signs that it may be time.

  • Decreased Range
  • Inconsistent Performance
  • No Response

As with programming a key fob, changing the battery of one can vary depending on the device or vehicle the key fob belongs to.

Here’s a general guide to help you change the key fob battery, but you should always refer to your product’s user guide for the most accurate instructions.

  1. Identify the Battery Type: Check the key fob’s user manual or open the key fob to find the battery number. Most key fobs use CR2025 or CR2032 lithium coin batteries, but it’s important that you use the correct type for your model.
  2. Open the Key Fob: Carefully pry open the key fob case. This can usually be done with a small flathead screwdriver or a purpose-built key fob opening tool. Some key fobs have a notch specifically designed for opening, while others may have screws that need to be removed.
  3. Replace the Battery: Once open, gently remove the old battery and replace it with the new one, making sure the positive (+) side is facing the correct direction, which is usually up.
  4. Close the Key Fob: Snap the key fob halves back together or replace any screws if necessary. Make sure the case is securely closed to avoid any damage or moisture getting inside.
  5. Test the Key Fob: After replacing the battery, test the key fob to make sure it’s working correctly.

The Bottom Line

Key fobs are key for modern access and vehicle control, relying on technologies like RFID and Bluetooth for operation. Proper maintenance, such as regular cleaning and timely battery replacement, alongside understanding their security features, like rolling codes and encryption, is important to prevent unauthorized access and ensure the longevity of the key fob.


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  1. Watch fob (Britannica)

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Marshall Gunnell
IT & Cybersecurity Expert
Marshall Gunnell
IT & Cybersecurity Expert

Marshall, a Mississippi native, is a dedicated expert in IT and cybersecurity with over a decade of experience. Along Techopedia, his bylines can be found on Business Insider, PCWorld, VGKAMI, How-To Geek, and Zapier. His articles have reached a massive readership of over 100 million people. Marshall previously served as the Chief Marketing Officer (CMO) and technical staff writer at StorageReview, providing comprehensive news coverage and detailed product reviews on storage arrays, hard drives, SSDs, and more. He also developed sales strategies based on regional and global market research to identify and create new project initiatives.  Currently, Marshall resides in…