> additional layer of confidentiality and authentication
and additional layers of attack surfaces
and additional layers of attack surfaces
One would naturally be the onion address. If they could break the 1024 bit RSA key, they could hijack the name. Risk of this happening: very low. Impact: massive especially outside the realm of tor.
Any additional risks you were thinking about? Backdoors in tor project? Hardware malware specifically designed for tor (rather than than being general)?
That said, I don't think there's any reason to believe Tor is any more likely to be vulnerable than any other software in your stack. The project is open source, and is very much written with a focus on security and privacy.