nRF51822 beacon kit and Windows 10

[TranceSKY]

Hi Folks,

I have a quick question about the Beacon kit. I'm working on a project that is going to use Windows 10 Hello companion device framework to build a Windows Lock/unlock experience. I need a BLE beacon device that should be able to store two 256 bit HMAC keys and release them with pressing a button on it.Its a two-way authentication between the beacon and W10 computer. So, can I use nRF51822 beacon kit to accomplish this project ? If I can, is there any known issues I may run into, or any good documentation on this topic?

Thanks for your answer.

Adam

[endnode]

Hi Adam,

BLE works in two modes:

1. Broadcaster/Observer with only one-directional unacknowledged data transfer (but with highest power efficiency).
2. Connection based.

Unfortunately for you BT SIG specification v4.0/4.1/4.2 allows only 31+31 bytes of payload in broadcasted data (and even less if device is compliant to GAP so must add certain formatting overhead and mandatory objects). BT 5.0 improved this but there will be no devices in the field for years so nothing for you probably. So you would need to have your application connection based but then surely you can do HMAC in SW and define how 2*32B will be formatted and transferred to the host. You just need to investigate how BLE API works on Windows 10 and how reactive it will be when your "device" will wake-up and ask for connecting (which side will be GAP Peripheral and which Central, how GATT Server/Client works and test which exact configuration will give you best performance = shortest time between button press and actual Windows unlock).

nRF51822 beacon kit can deliver all that. If your application won't meet your expectation it most probably won't be because Nordic but either Windows or general BLE limitations.

Cheers Jan

[TranceSKY]

Hi Jan,

Thank you for your quick answer. That was helpful. I'll focus on the Windows Hello Companion API as It's been improved a lot since the last W10 update and It can be a solution to this.

Thanks Adam

[endnode]

Great. Are you going to update this Q&A with your findings or do you considered it as answered already?