user9865: I am using an HC-05 bluetooth Module. How can I stop someone from pairing with my device by brute forcing the key? Failing that, and if someone does pair with my device, is there a way to authenticate the user? I was thinking of salted hash with a shared secret key. Is there anything better?

user72093: In case someone else asks the same question in the future, here's the answer...
Technically speaking, the Arduino cannot be hacked for the simple reason that it doesn't have an Operating System like other devices such as the Raspberry Pi, BeagleBone, Rock64 etc. So in as much as someone might be able to bruteforce the HC-05 pin and get access, there's pretty much nothing else they can do past that point, so my advice to you is that don't stress over it. However I would suggest adding a few security measures to your HC-05 Bluetooth module:

Change the default pin (0000 or 1234) to something else.
Lock the module to connect only to a specific device via the MAC Address and the AT+BIND command.

Cheers!

user7045: Configure your Bluetooth module to AT Command Mode
Then use AT+PIN Command to change the default PAIRING PIN of the Bluetooth Module.
Visit this link for more information about how to configure bluetooth to AT Mode

9865: <p>I am using an HC-05 bluetooth Module. How can I stop someone from pairing with my device by brute forcing the key? Failing that, and if someone does pair with my device, is there a way to authenticate the user? I was thinking of salted hash with a shared secret key. Is there anything better?</p>
 72093: <p>In case someone else asks the same question in the future, here's the answer...</p>
<p>Technically speaking, the Arduino cannot be hacked for the simple reason that it doesn't have an Operating System like other devices such as the Raspberry Pi, BeagleBone, Rock64 etc. So in as much as someone might be able to bruteforce the HC-05 pin and get access, there's pretty much nothing else they can do past that point, so my advice to you is that don't stress over it. However I would suggest adding a few security measures to your HC-05 Bluetooth module:</p>
<ol>
<li>Change the default pin (0000 or 1234) to something else.</li>
<li>Lock the module to connect only to a specific device via the MAC Address and the AT+BIND command.</li>
</ol>
<p>Cheers!</p>
 7045: <p>Configure your Bluetooth module to AT Command Mode</p>

<p>Then use <code>AT+PIN</code> Command to change the default PAIRING PIN of the Bluetooth Module.</p>

<p>Visit <a href="http://www.instructables.com/id/AT-command-mode-of-HC-05-Bluetooth-module/?ALLSTEPS" rel="nofollow">this link</a> for more information about how to configure bluetooth to AT Mode</p>
