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Just because you don't have signed certificates you can still protect against MitM attacks. Your browser just has to remember what the certificate was the first
by avar 16y ago
Just because you don't have signed certificates you can still protect against MitM attacks. Your browser just has to remember what the certificate was the first time, and alert you it if changes.
Sound familiar? It should, ssh(1) does this by default.
- tptacek 16y agoThe first time you connect to any SSH server, the connection can be hijacked. People used to do this for sport at Usenix. Why would anyone accept this weakness with their bank account? My mom barely understands the lock icon.
- avar 16y agoWhat sort of person goes to a conference like Usenix and connects to an external server for the first time? I've been to a dozen conferences, all of whom I've used ssh at, and I've never connected to an external box for the first time.
- tptacek 16y agoI can't imagine what possible point you could be trying to make. Am I making this up or not? I doubt I am, but who cares? The issue with first-connection security in SSH is a fact, not an opinion.
- avar 16y agoYes, first-connection security is not an option. But the vast majority of connections are not first connections. If I ssh to a new box at home, then go to Usenix and ssh warns me that the host key changed I'll have protected against MitM attacks, even if the original connection wasn't authenticated.
- tptacek 16y agoThat model works passably well for SSH connections. You make perhaps tens of those connections every day, from perhaps several devices. It doesn't work at Internet scale. It's too insecure. It's very unlikely that key continuity is going to replace PKI in HTTPS. Do I have strong opinions about PKI vs. key continuity? No. All I'm saying is that it's not a panacea. SSH-style key continuity is not the global solution for the certificate warning Firefox is annoying you with. You realize that Firefox already does this, right? Just hit "add exception" when the dialog pops up. Look! It works just like SSH!
- djcapelis 16y agoArguably, the right way of doing it is to use both. PKI to auth first connect, remember the chain to prevent bad CAs from giving certs people pretending to be BoA.
- pyre 16y agoWhy not abandon central key authorities and go distributed? Bring social networks and the web-of-trust together. "3 of your friends have said that they trust this certificate from Amazon.com. Do you want to accept it?"
- daeken 16y agoIf I had a dollar for every time a friend clicked a .exe email attachment, I'd be a very wealthy man. I damn sure don't trust my friends to verify the security of a cert.
- drdaeman 16y agoI have some security-savvy friends (who I'd trust) and some not so smart friends (who I don't trust on this subject). So, the obvious idea is to put weight coefficients on WoT digraph edges. But I have a feeling that this would be too complicated to manage.
- 16y ago
- peterwwillis 16y agoconsidering about every third time i visit a high traffic site with ssl i get a new cert pushed to me, i don't think ssh is a good comparison. also, perhaps i skipped over this, but tcpcrypt seems like a level of encryption well below application, thus if we did get a hijacker trying to 'change the self signed cert' after an initial connection (or just dropping the encryption) we wouldn't know, unlike ssl/browsers. am i incorrect?