BLE Connection by verifying thr enryption using ECDH

[srinivasa m]

hello everyone,

I have a task to establish the connection between the BLE peripheral and mobile application after verifying the encryption by exchanging the public key of the peripheral and mobile application using the ECDH algorithm. 

is it possible to exchange the keys before the connection and verify the security? if possible kindly suggest to me which example should I use. Kindly give me an idea on this.

Regards,

Srinivasa

[Einar Thorsrud]

Hi,

There is no way to exchange two-way data before connecting. But ECDH is the mechanism used in LE Secure Connections, so I assume that is what you are supposed to use? That is supported out of the box in the SDK. If you need an introduction to this I recomend you take a look at Lesson 5 – Security in Bluetooth LE communication of our Bleutooth course on the Nordic DevAcademy.

If the point is that you want to only support LE Secure Connections (key exchange via ECDH) and not legacy pairign, you can add CONFIG_BT_SMP_SC_ONLY=y to your project configuration, as demonstrated by the Bluetooth: Peripheral SC-only sample.

[srinivasa m]

Hi Einar 

Thanks for the response.

I am using nRFSDK 17.0.1 and how to enable the ECDH for pairing.

Regards,

Srinivasa M

[Einar Thorsrud]

Hi Srinivasa,

Most nRF5 SDK 17.x.x samples that support bonding support support LESC (LE Secure Connections is the standard way to do pairing with ECDH). You can serach for the examples and pick any that has a call to nrf_ble_lesc_request_handler() to see how LESC is handled.

PS: I recomend you migrate to SDK 17.1.0 if you want to stay on the nRF5 SDK as that has some important fixes and support the latest revision nRF52832 devices.

Br,

Einar