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If it is so easy to attack, then you already lost the game unless you've pinned the fedoraproject certs. The CA model has been demonstrated broken long ago. S

by clarry 12y ago

If it is so easy to attack, then you already lost the game unless you've pinned the fedoraproject certs. The CA model has been demonstrated broken long ago. So would you rather trust that model, or just obtain the OpenBSD key for yourself via multiple different channels, from multiple sources? The key, by the way, is all over the place. You start with the official site, but you can cross-check against all the CVS mirrors, and you can check all mailing list archives which contain the key in the release announcement. I would dare say that is heck of a lot better than simply trusting your CAs, if you are indeed so easily attacked.

cesarb 12y ago
Without TLS and having control of the network, it doesn't matter how many channels over the network you use; it's simple to MITM everything and search-and-replace all text matching the key with your forged key (in fact, many networks already MITM all non-TLS HTTP traffic through a "transparent proxy"). With TLS, even with the imperfect CA model, it's much harder. It might have been "demonstrated broken", but can you get a certificate for "fedoraproject.org"? It's not that easy. Add to that the Certificate Patrol extension, which warns the user quite noisily when a certificate is signed by a different CA (and shows the user the old and new CA). With mailing the CDs, as suggested several posts upthread, it also gets harder; now the attacker has to MITM two things (the network and intercept the physical disks). If you add TLS, it gets even harder (three things: MITM the network, intercept the physical disks, and obtain a valid forged certificate). So, trusting the CAs is better than getting the key via multiple unencrypted channels through the same network. Trusting the CAs plus getting the key via multiple channels is even better. The methods are not exclusive, and "multiple channels" is already common in practice (in my Fedora example, the DVD image is obtained via bittorrent, while the key is obtained via TLS, and they have to match).
- clarry 12y ago
  By multiple channels I mean not just channels over a single network. You can access all these key sources from different networks.
farawayea 12y ago
Please read again, I never said anything about any fedora.

by clarry 12y ago

cesarb 12y ago

Without TLS and having control of the network, it doesn't matter how many channels over the network you use; it's simple to MITM everything and search-and-replace all text matching the key with your forged key (in fact, many networks already MITM all non-TLS HTTP traffic through a "transparent proxy"). With TLS, even with the imperfect CA model, it's much harder. It might have been "demonstrated broken", but can you get a certificate for "fedoraproject.org"? It's not that easy. Add to that the Certificate Patrol extension, which warns the user quite noisily when a certificate is signed by a different CA (and shows the user the old and new CA). With mailing the CDs, as suggested several posts upthread, it also gets harder; now the attacker has to MITM two things (the network and intercept the physical disks). If you add TLS, it gets even harder (three things: MITM the network, intercept the physical disks, and obtain a valid forged certificate). So, trusting the CAs is better than getting the key via multiple unencrypted channels through the same network. Trusting the CAs plus getting the key via multiple channels is even better. The methods are not exclusive, and "multiple channels" is already common in practice (in my Fedora example, the DVD image is obtained via bittorrent, while the key is obtained via TLS, and they have to match).

clarry 12y ago
By multiple channels I mean not just channels over a single network. You can access all these key sources from different networks.

farawayea 12y ago

Please read again, I never said anything about any fedora.