For this to work we need free certificates. Many still keep referring to StartSSL, but there you just pay double later on in revocation fees. https://www.startssl.com/?app=43
https://tools.ietf.org/html/rfc6698
What, your domain doesn't have DNSSEC because your registrar doesn't offer it? It'll have to have the opportunity to next year, if they want to renew their contract with ICANN...
- Any time a certificate could be impersonated by an attacker, the attacker is also able to block a revocation check.
- Live revocation checks (A) kill performance, and (B) leak information as a side-channel.
- You could solve this by predownloading every single revocation ever. But that is massive (infeasible for mobile), never going to be up to date, and leaks information about private domains.
See Adam Langley's blog for more about OCSP vs CRLsets.
The next step up from that would be unsigned public keys with pinning (like ssh) to reduce MITM, and finally above that would be identity verification on the level of https.
That is a common misconception. If I MITM when you establish connection, how would you notice? My self-signed certificate looks like a real one.
That's why we need CAs (or WoT, or whatever), to verify identity after we've established a secure channel.
Best solution? Not by a long shot, but it is a reasonably simple one to implement and does improve things.
It would not be acceptable to trade the ability to change SSL keys for a trust-on-first-use model. There are solutions to this of course, but also tradeoffs. These needs to be taken into account.
How? An encrypted connection subject to MITM is as secure as an non-encrypted one. Attackers will stop listening for plaintext credentials at WiFi spots and will just launch their favorite HTTPS MITM tool instead.
Certificate pinning is flawed because you cannot revoke certificates from your clients. How would you distinguish a MITM attack from a certificate change? And if you can't revoke certificates, what happens after an attacker gains access to the private keys? Definitely flawed model.
HTTPS without identity verification is even worse than HTTP. IMHO a false sense of security is more dangerous than no security. Self-signed certificates must not be advertised as secure by browsers (the famous lock icon) because they are not! This would render them invisible for most users.
Self-signed certificates are only viable for tech-savvy users, and even then the dangers are too many and the burden too heavy (did the server change certs, or am I being subject to a MITM attack?) for them to be useful.
1. Opportunistic encryption without certificates or identity pinning -- protects against dragnet surveillance and packet sniffing, but not MITM.
2. Encryption with pinned self-signed certs -- protects against second connection MITM, but not stolen certs without some revocation design.
3. Encryption and identity verification with CA- or WoT-signed certs -- protects against first connection MITM except by powerful adversaries.
The CA idea is broken but not too easy to replace. http://convergence.io/ could be a few steps forward.
This is what we tell users to do today for important sites, and not click in links in mail or elsewhere. It is not obvious that there is a net benefit in security.
Well, you decide whether you want to trust the person on the certificate, and if the security ever changes again that'd be the red flag. Initial trust is always difficult.