5 ms·

How do you verify the cert then? If you can't verify the cert, you have no way to know it is not being man in the middled.

• fortran77 6y ago
  How about putting some hash of the self-signed cert in a DNS TXT field?
  • kop316 6y ago
    That could help, but if someone is MITMing you, DNS is all in the clear too. I do not enough to solve that problem really.
  • kondu 6y ago
    A MITM can intercept and modify dns requests too.
• PeterisP 6y ago
  Self-signed certs don't protect against active man in the middle attacks, but they do establish an encrypted channel that is secure against passive eavesdropping and after-the-fact decryption of network captures. So there's still some security benefit there.
  • kerkeslager 6y ago
    There really isn't a real-world situation I can think of where I'd care about passive eavesdropping or after-the-fact decryption and not also care about active eavesdropping. So I'm going to disagree. No, there is no security benefit to encryption without authentication.
    • PeterisP 6y ago
      While the impact of all these things are the same, the likelihood is not. There certainly are real world situations where the chance of active eavesdropping (which requires a targeted attack, and is risky because it can be detected) is low, so you accept that level of risk, but the ability for someone to just grab all the traffic of a large group (that just happens to include you) for a prolonged period of time undetected is much higher.
      • kerkeslager 6y ago
        That's a good point. I may be wrong--I'll have to consider this a bit more.
• dtech 6y ago
  You don't, but I don't like that mindset that an unverified certificate is somehow not better or even worse (see browser UIs) than no encryption. Encryption prevents sniffing, Encryption + trust prevents sniffing and MITM. Providing sniffing protection is an upgrade. As an example, say HTTP would always upgrade to HTTPS with a server provided public key. That would be more secure than the HTTP we have today, even though it wouldn't prevent MITM.
  • skrebbel 6y ago
    I don't understand, anyone who can MITM can also sniff, right?
    • kop316 6y ago
      Yes they can. They simply decrypt, and reencrypt with their own self signed cert. If you have no way to verify the self-signed cert, you would never know.
    • naniwaduni 6y ago
      An adversary with MitM capability needs to commit to being detectable in order to read encrypted traffic.
    • dtech 6y ago
      but not everyone who can sniff can MITM, encryption always prevents sniffing
  • jackewiehose 6y ago
    > I don't like that mindset that an unverified certificate is somehow not better or even worse (see browser UIs) than no encryption Of course it's worse when the user thinks the connection is encrypted when he actually has no idea who he's talking to. What kind of attack do you have in mind where someone can sniff on the data but not tamper with it? And how should a browser explain this situation to the user? No, the mindset that an unverified certificate is better than no encryption is very dangerous.