[smeej]

But you can check this. You can monitor whether info is leaving on other channels. And you can sign on an air-gapped computer and transfer only the signed transaction hash (never the privkey) to a connected one to broadcast. You can do all but the actual signature with open source tools.

Just because you haven't taken the time to learn how this stuff works doesn't mean there aren't thousands of incredibly intelligent people who have been working on it for a decade and have actually solved the low-level concerns you have.

[JonathanBeuys]

You cannot monitor all channels when you use just a single way to create your hashes.

Example: If you use a single hardware wallet to sign your transactions, you have no way to know if the wallet transmits data out via the hashkey:

https://news.ycombinator.com/item?id=32181462