Our main issue is if someone tampers with content stored on the server, which gets copied to devices. For example someone replaces a JPG with the wrong JPG that

Our main issue is if someone tampers with content stored on the server, which gets copied to devices. For example someone replaces a JPG with the wrong JPG that is something offensive. If someone gains access to our server, its already game over. Being able to execute code on the devices is then moot because we were already hacked & potentially lost all credibility in the industry. To everyone saying not to execute code at URL, this is how oh my zsh, and many other open source projects are installed. And SSL should prevent any kind of MITM attacks. The point about keeping keys off the server is a good idea, but is not always possible when the server needs to dynamically send content down to the device. The server would need to access the private key in order to sign this content dynamically. For statically built executables this is a good idea though.