X.509 has a top-down security model, which has benefits in authoritative deployment scenarios but is also vulnerable to things like seen today. Chrome's ca-cha

X.509 has a top-down security model, which has benefits in authoritative deployment scenarios but is also vulnerable to things like seen today. Chrome's ca-chain pinning is only available for a selected group of sites, e.g. google, twitter, tor2web while everyone can get their properties into the HSTS list (doesn't help if any CA goes bad). This hard-coded, limited list does not scale. We need a bottom-up model, that allows something like pinning or "per-certificate" trust instead of recursive CA trust. This should not only work for things like TLS but also for S/MIME. In addition, OS and browser vendors should ask the user before some certs are trusted or at least make it very easy to untrust a lot. On OS X it's a PITA to double click every CA cert and untrust it manually.