Should you ever really trust kiosk machines? They could easily be setup with MITM eavesdropping software.
> What about https domains for images and scripts? Is the user supposed to trust each domain separately?
Presumably there could be some sort of <meta> header that listed the public key fingerprint/IDs of any subdomains that the page was going to pull in. This would make the UX better.
> Assuming trusting a domain trusts all its other domains mentioned in its content-security-policy, how is this trust revoked for misuse?
AFAIK, revocation isn't very good even with the current CA infrastructure[1][2].
[1] https://news.netcraft.com/archives/2014/04/24/certificate-re...
[2] https://www.maikel.pro/blog/current-state-certificate-revoca...