Deploying Bluetooth® Low Energy and NFC for secure connections and easy pairing : Page 2 of 5

August 23, 2016 //By Heiner Tendyck
Deploying Bluetooth® Low Energy and NFC for secure connections and easy pairing
By supporting wireless applications that can operate with ultra-low power consumption, Bluetooth Low Energy (BLE) opens up a number of new application opportunities for designers - particularly when it is combined with the benefits of NFC technology.

NFC tagging reduces IoT power consumption

Take, for example, applications such as smart meters that may be read manually at intervals of several weeks or months. The meter connectivity circuit can remain completely powered down until the operator brings an NFC reader or NFC-enabled mobile into close proximity (“tagging”). The initial energy to wake the meter is supplied via the NFC antenna, meaning the BLE device can be in deep sleep mode all the time to ensure minimal power consumption as the BLE IoT node does not check for communication requests (“advertising”) when it is not needed for a long period of time. Once the credentials of the reading device have been established, a connection can be established using BLE.


Out of Band (OoB) pairing in practice

Although, at first, this may seem to be complex, in practice the pairing and communication is quite simple and intuitive. In effect, NFC and Bluetooth each ‘play to their strengths'.

Firstly, the mobile device is placed close to the NFC-enabled device - say a smartphone or tablet being touched against a payment terminal or maybe a printer in an office environment. In devices equipped with Toshiba's TC35670 Bluetooth Low Energy + NFC Tag IC, energy from the NFC antenna in the mobile device will 'wake' the fixed device, which transmits its Bluetooth credentials securely via NFC.

As the mobile device detects that the fixed device is present, it initiates a pairing request via NFC. This removes the need for the user to check and enter a numeric string that confirms the correct devices are being paired. The secure transfer prevents the security keys being inadvertently, or maliciously, intercepted by the 'Man in the Middle'.

The pairing is now complete and both devices are able to open a secure, AES-128 encrypted, Bluetooth communication to conduct data transfer. The mobile handset may initiate an application depending on the NFC data content.

Figure 1: Combined BLE and NFC design comprising the Toshiba’s TC35670 Bluetooth Low Energy + NFC Tag IC, Bluetooth and NFC antenna.

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