Obviously, any device that communicates with an untrusted 3rd party whenever it's turned on is not even trying to be trustworthy. Watching for any unexpected network traffic would be a very basic step in assessing the trustworthiness of a device.
I suppose, lacking the kind of efforts that Bunnie is making, the best you can do is start with relatively simple mass produced hardware, purchase it in a way that it can't be tampered with specifically for you, install an open-source OS which doesn't communicate with 3rd parties, check the software checksums.
Some applications, like vote counters, may not even need an Internet connection. Creating a secure system to count votes isn't something I'd like to be asked to do.
I suppose, lacking the kind of efforts that Bunnie is making, the best you can do is start with relatively simple mass produced hardware, purchase it in a way that it can't be tampered with specifically for you, install an open-source OS which doesn't communicate with 3rd parties, check the software checksums.
Some applications, like vote counters, may not even need an Internet connection. Creating a secure system to count votes isn't something I'd like to be asked to do.