4 ms·

Is it correct to say that if the government demands CloudFlare's SSL cert private key (or acquires it surreptitiously) then they'll be able to decrypt every pac

Is it correct to say that if the government demands CloudFlare's SSL cert private key (or acquires it surreptitiously) then they'll be able to decrypt every packet served by CloudFlare? In other words, if the government seizes your cert, then every website that uses CloudFlare will become vulnerable? I came to that conclusion after realizing that CloudFlare doesn't require websites to set up SSL properly (or perhaps at all?) Are you using a different SSL cert for each website? Actually, such a thing would probably be completely cost prohibitive even if you wanted to. So therefore it must be true that if someone seized your central SSL key then everyone who uses CloudFlare will lose all security. This may or may not be an issue; it's my understanding that CloudFlare only serves static, public content, which of course wouldn't be useful to any authorities. But after thinking about it for a bit, I'm concerned about their ability to impersonate users of a CloudFlare-hosted website. Do users' cookies ever get sent to CloudFlare servers? (E.g. my cookies for HN.) That would mean anyone who can obtain those cookies could impersonate any user. Therefore if a government were targeting a specific user and has obtained CloudFlare's SSL cert, then they can wait for that user to log in to the website, steal their cookies, then impersonate the user and download all information from the target website. (CloudFlare itself could do this if it wanted to.) Hence the government wouldn't need to inform individual companies that they're targeting a particular user. Therefore it can't be true that any user cookies are ever transmitted to CloudFlare's servers, since that would be such a big security risk, right? But then I don't understand how CloudFlare would offer any benefit to a website where the majority of users are logged in. And I'd assume that lack of cookies would cause problems for targeted advertising. So, is it correct that if CloudFlare receives users' cookies, then anyone who has CloudFlare's cert can obtain those cookies (via passive monitoring) and hence can impersonate any user on any website that uses CloudFlare? It's entirely possible I'm making a fool of myself with this post, but it's unclear to me how it'd be possible for CloudFlare to serve a website's content without also receiving requests (which contain user cookies) for that website. So it seems like origin SSL certs wouldn't even offer any security if CloudFlare ever receives any user cookies.

jgrahamc 13y ago
There is no single CloudFlare certificate/private key, that's not how CloudFlare works. The certificate for Hacker News is unique to Hacker News. We deal with thousands and thousands of certificates. Since HTTP/HTTPS requests for sites on CloudFlare pass through CloudFlare so do all parts of the HTTP header (including the Cookies). But since the certificate is unique to HN there's no more danger of a government compelling access to the certificate/key than there is if HN wasn't on CloudFlare (since the government could compel HN to give up the certificate/key). Additionally, we would fight vigorously against an order to give up a private key. The foundation of our business is trust. But it's interesting that you bring this up because we are shortly going to announce a new offering where even if the government tried to compel us to give up a private key we would literally be unable to do so. Stay tuned. And, by the way, that product will be open source.
- sillysaurus2 13y ago
  Still, does CloudFlare ever receive user cookies, e.g. my Hacker News cookies? A single weak spot in your cert management security practices (or a demand from a government) would compromise all of those thousands of certificates. And if you receive user cookies, then it seems true that anyone who has those certificates can obtain all user data from any of those websites. I'm confused how it's possible to let anyone sign up for CloudFlare for free within minutes, while also generating a certificate unique to their website, signed by a CA, because a signed CA SSL cert always costs money. For a website like CloudFlare, that would be a significant cost, wouldn't it? EDIT: I wrote my reply before your edit that gave the answer (yes, CloudFlare has all user cookies from all websites). Sorry. However: it's interesting that you bring this up because we are shortly going to announce a new offering where even if the government tried to compel us to give up a private key we would literally be unable to do so. This would be illegal. The US government has already asserted multiple times that it has the authority to compel any US website to give up any keys it demands. You will suffer the same fate as Lavabit: to be fined >$1k per day until you comply, with penalties increasing until you're unable to cover the cost. So what's your plan?
  - jgrahamc 13y ago

jgrahamc 13y ago

There is no single CloudFlare certificate/private key, that's not how CloudFlare works. The certificate for Hacker News is unique to Hacker News. We deal with thousands and thousands of certificates. Since HTTP/HTTPS requests for sites on CloudFlare pass through CloudFlare so do all parts of the HTTP header (including the Cookies). But since the certificate is unique to HN there's no more danger of a government compelling access to the certificate/key than there is if HN wasn't on CloudFlare (since the government could compel HN to give up the certificate/key). Additionally, we would fight vigorously against an order to give up a private key. The foundation of our business is trust. But it's interesting that you bring this up because we are shortly going to announce a new offering where even if the government tried to compel us to give up a private key we would literally be unable to do so. Stay tuned. And, by the way, that product will be open source.

sillysaurus2 13y ago
Still, does CloudFlare ever receive user cookies, e.g. my Hacker News cookies? A single weak spot in your cert management security practices (or a demand from a government) would compromise all of those thousands of certificates. And if you receive user cookies, then it seems true that anyone who has those certificates can obtain all user data from any of those websites. I'm confused how it's possible to let anyone sign up for CloudFlare for free within minutes, while also generating a certificate unique to their website, signed by a CA, because a signed CA SSL cert always costs money. For a website like CloudFlare, that would be a significant cost, wouldn't it? EDIT: I wrote my reply before your edit that gave the answer (yes, CloudFlare has all user cookies from all websites). Sorry. However: it's interesting that you bring this up because we are shortly going to announce a new offering where even if the government tried to compel us to give up a private key we would literally be unable to do so. This would be illegal. The US government has already asserted multiple times that it has the authority to compel any US website to give up any keys it demands. You will suffer the same fate as Lavabit: to be fined >$1k per day until you comply, with penalties increasing until you're unable to cover the cost. So what's your plan?
- jgrahamc 13y ago