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Showing no warning for self-signed certs would make it much easier to MitM https. For example: Let's say Bob has an https site with a valid (CA-signed) cert. Al
by ggreer 12y ago
Showing no warning for self-signed certs would make it much easier to MitM https. For example: Let's say Bob has an https site with a valid (CA-signed) cert. Alice tries to connect to Bob. Mallory intercepts the connection, connects to Bob, and responds to Alice with a self-signed cert. Alice sees no warning, but her communications are being intercepted and possibly tampered.
- feld 12y agoNo, they would get a warning if it's self-signed "google.com" certificate which doesn't match the one in the Certificate Transparency registry, or OCSP fails, or HPKP fails to match, DANE/Tack fails to match. At least that's what a sane implementation would do.
- sp332 12y agoAren't all of those vulnerable to denial of service attacks? If the "man in the middle" just drops all OCSP requests on the floor, for example, the default case is to accept everything.
- nine_k 12y agoIf you can't access all the certificate-verifying services at once, it's high time to show a warning anyway.
- ggreer 12y agoCertificate Transparency is to detect compromised or malicious CAs, and typically only lets people know about problems after the fact. How would OCSP help with a self-signed certificate? What CA would the OSCP request go to? And cert pinning only works if you've visited the site before while not being MitMed. A lot of these extensions to TLS help secure popular sites like Google, but they don't scale to the many small-but-important sites such as your local credit union. Instead of adding so much complexity, it's much easier and safer to keep current behavior and warn on self-signed certs.