Why we ask you to move your mouse

When you create your vault, Privt Voice asks you to wave your mouse around while a field of characters blooms across the screen. It looks like security theatre. This post is the honest breakdown — because a privacy product that isn't precise about its own claims doesn't deserve your trust.

What actually happens

Your encryption keys need randomness — unpredictability is the entire game. Your Mac already has an excellent source: a hardware random generator feeding the operating system's pool, and that alone is cryptographically sufficient. If we never asked for your mouse, your keys would still be strong.

But when you move your mouse, we collect the coordinates and microsecond timings of hundreds of movements and mix them into key generation: the system's randomness and a hash of your movements are combined through a key-derivation function, and the result becomes your keys. By construction the mix can only add unpredictability — even if your movements were somehow perfectly predictable, the keys would be no weaker than the hardware randomness alone.

Why keep it, then?

Two reasons. First, the hedge is real, costs three seconds, and adds a layer that came from a human hand rather than any silicon we have to trust. Second — and we'll own this — it makes a true thing visible. Your keys really are being born in that moment, on that machine, from randomness no one else could reproduce. Watching it happen tells the truth better than a progress bar ever could.