How NFC Works

[Jollier]

NFC (Near Field Communication) is a short-range wireless communication technology that allows data exchange between devices at a distance of up to 10 cm. It is widely used for payment via smartphones, reading tags (for example, on goods or posters), exchanging contacts and other tasks. Let's see how it works:

Basic principles of operation​

1. Frequency and standards:
   • NFC operates at 13.56 MHz and complies with ISO/IEC 14443 standards (as with contactless smart cards).
   • The technology is based on the principles of radio frequency identification (RFID), but differs in its support for two-way communication and higher data transfer rates (up to 424 kbps).
2. Inductive coupling:
   • NFC devices use electromagnetic induction to transmit data.
   • One device (for example, a smartphone) generates an electromagnetic field, and the second (for example, a payment terminal) uses this field to obtain energy and transmit data.
   • Antennas in devices are coils that create and receive signals.
3. Operating modes:
   • Active mode: Both devices generate their own electromagnetic field and exchange data. For example, two smartphones transfer files.
   • Passive mode: One device (e.g. NFC tag) does not have its own power supply and uses the energy of the active device's field. Tags store data that is read by the smartphone.
   • Read/write mode: The device (e.g. smartphone) reads data from a passive medium (tag) or writes new data.

Examples of use​

• Contactless payment: A smartphone or card with NFC is brought to the terminal - payment data is encrypted and transmitted.
• Reading tags: NFC stickers in advertisements or products contain information (links, instructions) that automatically open on a smartphone.
• Share data: Two devices transfer contacts, media files, or set up a Wi-Fi connection when touched.
• Smart home: NFC tags control household appliances (for example, turning on the light when you bring your phone near).

Safety​

• Encryption: Data is transmitted in encrypted form.
• Authentication: Devices verify each other before exchanging data.
• Short range: Minimizes the risk of signal interception.
• SE (Secure Element): In smartphones, payment data is stored in an isolated, secure chip.

Comparison with other technologies​

• Bluetooth: NFC works over shorter distances (up to 10 cm versus 10 m for Bluetooth), but requires less energy and establishes a connection faster.
• Wi-Fi Direct: Faster, but more difficult to set up and requires more power.
• RFID: NFC is more secure and supports two-way communication, while classic RFID is often one-way.

NFC Components​

• NFC chip: Manages the encoding and decoding of data.
• Antenna: Transmits and receives signals.
• Modulation: Signals are encoded using ASK (Amplitude Shift Keying) or FSK (Frequency Shift Keying).

NFC thus combines ease of use, energy efficiency and security, making it ideal for everyday tasks such as payment, identification and information exchange.

 

[Professor]

NFC (Near Field Communication) is a short-range wireless communication technology (up to 10 cm) that allows data exchange between devices. It is used for:

• Contactless payments (Apple Pay, Google Pay, cards with PayPass/PayWave chip).
• Data transfer (contacts, links, files).
• Automation of tasks (NFC tags for smart home).

How NFC Works​

1. Physical basis​

• Operates at 13.56 MHz (ISO/IEC 14443 standard).
• To communicate, you need two devices:
  • Active (smartphone, payment terminal) – generates the field itself.
  • Passive (card, tag) – powered by the field of the active device.

2. Operating modes​

Mode	How it works	Example
Read/Write	The smartphone reads or writes data to the NFC tag	Scanning a tag in an advertisement
P2P (Peer-to-Peer)	Two devices exchange data	Android Beam Contact Transfer
Card emulation	Smartphone simulates NFC card (payments, passes)	Apple Pay / Google Pay

3. NFC in payments​

1. The buyer places the phone/card near the terminal.
2. The terminal creates an electromagnetic field that activates the chip.
3. Card data (encrypted token) is transmitted to the bank.
4. The bank checks and confirms the payment (3D-Secure, if required).
5. Money is debited without transferring the actual card number (a token is used).

NFC Security​

Short radius (10 cm) makes interception difficult.
Tokenization – a one-time code is transmitted instead of the card number.
Encryption (EMV standard).

Risks:

• Skimming (if the card is not protected by CVC3).
• NFC readers in the crowd (rare, but possible reading in crowded places).

How to protect yourself?

• Turn off NFC when not in use.
• Use virtual cards (Revolut).
• Set passwords for labels.

Where else is NFC used?​

• Passes (metro, office cards).
• Smart home (automation via tags).
• Medicine (NFC bracelets with medical history).

NFC is convenient and safe if you are careful.