6 ms·

So CloudFlare won't get your private key, but will still get to see unencrypted plaintext for all traffic? Sounds like a huge improvement...

jgrahamc 12y ago
What threat are you concerned about?
- praseodym 12y ago
  I don't really see the security improvement. Actually the key server would be an new attack vector, although one that could be firewalled pretty well.
  - sarciszewski 12y ago
    Using CloudFlare implicitly requires trusting CloudFlare. With this, CloudFlare cannot impersonate you without your endpoint's active consent. As soon as you terminate the service that solves this puzzle for CF, they cannot impersonate you any longer. So, yes, it is better. Maybe not "great" if your threat model includes CF getting 0wned, but definitely better than giving over your RSA key. ;)
    - marcosdumay 12y ago
      And that's why regulations make it almost impossible for banks to use CloudFare. But CloudFare sees that as a problem, and makes some effort to create a loophole. You can't claim that this improves the bank clients' security. It's clearly worse than doing nothing.
      - sarciszewski 12y ago
        Think of it as a compromise: You can leverage CloudFlare's CDN to mitigate DDoS and other sorts of nasty attacks AND assure TLS is used with every connection, without giving up your RSA key. "It's clearly worse than doing nothing." It's not very clear to me. Please explain.
        km3k 12y ago
        I think "It's clearly worse than doing nothing" is from a purely security perspective. This opens up a larger attack surface, so it's worse in terms of security. But it's better than doing nothing from a business perspective, since it allows for better performance and better handling of DDOS attacks. It's a comprimise. Potentially it is slightly worse in security, but it is much better for performance and uptime.
    - grossvogel 12y ago
      I think the parent means the key server the bank exposes to CF is a new attack surface. If an attacker could impersonate CF and connect to the key server, they too could authenticate connections as the bank without having the key.
  - nknighthb 12y ago
    It is a huge improvement. Nobody can impersonate the bank without the bank's cooperation. When cooperation ends, so does the ability to impersonate. This is not the case with any mechanism that requires you to hand over your keys. Not even issuing a revocation effectively terminates use of a compromised key.
    - xorcist 12y ago
      There is no practical improvement here. What does it matter security-wise if the HSM module (which is what banks use) physically sits on Cloudflare premises or off Cloudflare premises? It's still connected to the same equipment. It does matter for a variety of other reasons, for example what security clearances are required to work there, but it does not matter much for security.
      - tokenizerrr 12y ago
        Now cloudflare employees will have no possible access to the private key, nor do intruders who break into the cloudflare servers. This keeps the bank in full control of who has access to the key, they can stop responding to signing requests at any time and then keep trusting the key on their own servers in the future.
        xorcist 12y ago
        Cloudflare employees will have no access to the key inside a HSM even if it colocated on their premises. That's why you use them. Please summarize the differences between this protocol and PKCS instead of downvoting.
        nknighthb 12y ago
        Without a system like this, you would require many HSMs physically co-located with every server around the world, you would be trusting entirely in the ability of the HSM to withstand prolonged physical attack/analysis by a highly-resourced adversary (I'd consider this security suicide), and you would still not have the ability for the bank to cut off impersonation at any moment. I have, incidentally, downvoted your comment, because you are complaining about downvotes. Don't do that.
- spindritf 12y ago
  You get to see all the credentials, passwords, balances, private information... of banks' customers. This is no doubt an improvement, you may even be more technically capable than the bank itself, but if someone breaches CloudFlare, they can still get everything they would want from hijacking a connection to a bank.
vidarh 12y ago
The big deal is that CloudFlare's ability to sign SSL sessions can be yanked with the flip of a switch, with no need to trust CloudFlare. Of course you still need to trust CloudFlare to let them provide SSL functionality for you in the first place. But often the issue of "do I trust them today?" is separate from "will I still trust them tomorrow? and what happens if I don't?". E.g. consider if I trust CloudFlare today, but want to be protected in the event that they fail and suffer intrusion. With this service, I could as an emergency just flip a switch (shut down the devices providing the key signing) and instantly disable CloudFlare's ability to accept SSL connections on my behalf, without having to trust that they manage to deal with the intrusion properly. By allowing me to put less trust in them, I may trust them more, because the ability to counteract misplaced trust is much better.
- michaelt 12y ago
  The big deal is that CloudFlare's ability to sign SSL sessions can be yanked with the flip of a switch, with no need to trust CloudFlare. Sounds like we'll be able to close the stable door within seconds of the horse bolting. Surely now the federal regulators will let us keep the barn door open?!
  - Dylan16807 12y ago
    They're worried about the other 5 million horses in there. You always have to trust some server with the plaintext, unless you want a barn that has no door at all. CloudFlare practices good security. This makes the marginal risk from moving sites onto their servers minimal or even negative, since you only have to worry about the current good security and not CloudFlare-in-six-years security.
vader1 12y ago
Indeed. Imagine an internet user who uses online banking with one of these banks; registered his domains with Namecheap; keeps some bitcoins at Coinbase; pseudonymously frequents Reddit; and posts anonymously at 4chan every now and then. By merely passively eavesdropping on all traffic from and to your IP address, Cloudflare can build a profile that links your real world identity to all your Reddit posts you thought were anonymous; to the naughty threads you visited on 4chan; to the amount of money in your bank account; and to the domains and bitcoin addresses you own. This is something that neither your ISP or any of those individual site owners could ever do, and which might even make the NSA a bit jealous. Now consider what Cloudflare could do on your behalf (and make it look like it was you) if, say, a disgruntled employee was actively out to get you. I'm not at all saying that there is any reason to distrust Cloudflare, but is it not an enormous amount of power to place in the hands of one entity? Even more so than we do with parties like Google or Facebook, which get immensely more scrutinized over it?
- astrange 12y ago
  4chan's posting API is actually not (as of this very second) behind Cloudflare.
m1keil 12y ago
previously they had your private key, so they could see unencrypted plaintext anyway.

jgrahamc 12y ago

What threat are you concerned about?

praseodym 12y ago
I don't really see the security improvement. Actually the key server would be an new attack vector, although one that could be firewalled pretty well.
- sarciszewski 12y ago
  Using CloudFlare implicitly requires trusting CloudFlare. With this, CloudFlare cannot impersonate you without your endpoint's active consent. As soon as you terminate the service that solves this puzzle for CF, they cannot impersonate you any longer. So, yes, it is better. Maybe not "great" if your threat model includes CF getting 0wned, but definitely better than giving over your RSA key. ;)
  - marcosdumay 12y ago
    And that's why regulations make it almost impossible for banks to use CloudFare. But CloudFare sees that as a problem, and makes some effort to create a loophole. You can't claim that this improves the bank clients' security. It's clearly worse than doing nothing.
    - sarciszewski 12y ago
      Think of it as a compromise: You can leverage CloudFlare's CDN to mitigate DDoS and other sorts of nasty attacks AND assure TLS is used with every connection, without giving up your RSA key. "It's clearly worse than doing nothing." It's not very clear to me. Please explain.
      - km3k 12y ago
        I think "It's clearly worse than doing nothing" is from a purely security perspective. This opens up a larger attack surface, so it's worse in terms of security. But it's better than doing nothing from a business perspective, since it allows for better performance and better handling of DDOS attacks. It's a comprimise. Potentially it is slightly worse in security, but it is much better for performance and uptime.
  - grossvogel 12y ago
    I think the parent means the key server the bank exposes to CF is a new attack surface. If an attacker could impersonate CF and connect to the key server, they too could authenticate connections as the bank without having the key.
- nknighthb 12y ago
  It is a huge improvement. Nobody can impersonate the bank without the bank's cooperation. When cooperation ends, so does the ability to impersonate. This is not the case with any mechanism that requires you to hand over your keys. Not even issuing a revocation effectively terminates use of a compromised key.
  - xorcist 12y ago
    There is no practical improvement here. What does it matter security-wise if the HSM module (which is what banks use) physically sits on Cloudflare premises or off Cloudflare premises? It's still connected to the same equipment. It does matter for a variety of other reasons, for example what security clearances are required to work there, but it does not matter much for security.
    - tokenizerrr 12y ago
      Now cloudflare employees will have no possible access to the private key, nor do intruders who break into the cloudflare servers. This keeps the bank in full control of who has access to the key, they can stop responding to signing requests at any time and then keep trusting the key on their own servers in the future.
      - xorcist 12y ago
        Cloudflare employees will have no access to the key inside a HSM even if it colocated on their premises. That's why you use them. Please summarize the differences between this protocol and PKCS instead of downvoting.
        nknighthb 12y ago
        Without a system like this, you would require many HSMs physically co-located with every server around the world, you would be trusting entirely in the ability of the HSM to withstand prolonged physical attack/analysis by a highly-resourced adversary (I'd consider this security suicide), and you would still not have the ability for the bank to cut off impersonation at any moment. I have, incidentally, downvoted your comment, because you are complaining about downvotes. Don't do that.
spindritf 12y ago
You get to see all the credentials, passwords, balances, private information... of banks' customers. This is no doubt an improvement, you may even be more technically capable than the bank itself, but if someone breaches CloudFlare, they can still get everything they would want from hijacking a connection to a bank.

vidarh 12y ago

The big deal is that CloudFlare's ability to sign SSL sessions can be yanked with the flip of a switch, with no need to trust CloudFlare. Of course you still need to trust CloudFlare to let them provide SSL functionality for you in the first place. But often the issue of "do I trust them today?" is separate from "will I still trust them tomorrow? and what happens if I don't?". E.g. consider if I trust CloudFlare today, but want to be protected in the event that they fail and suffer intrusion. With this service, I could as an emergency just flip a switch (shut down the devices providing the key signing) and instantly disable CloudFlare's ability to accept SSL connections on my behalf, without having to trust that they manage to deal with the intrusion properly. By allowing me to put less trust in them, I may trust them more, because the ability to counteract misplaced trust is much better.

michaelt 12y ago
The big deal is that CloudFlare's ability to sign SSL sessions can be yanked with the flip of a switch, with no need to trust CloudFlare. Sounds like we'll be able to close the stable door within seconds of the horse bolting. Surely now the federal regulators will let us keep the barn door open?!
- Dylan16807 12y ago
  They're worried about the other 5 million horses in there. You always have to trust some server with the plaintext, unless you want a barn that has no door at all. CloudFlare practices good security. This makes the marginal risk from moving sites onto their servers minimal or even negative, since you only have to worry about the current good security and not CloudFlare-in-six-years security.

vader1 12y ago

Indeed. Imagine an internet user who uses online banking with one of these banks; registered his domains with Namecheap; keeps some bitcoins at Coinbase; pseudonymously frequents Reddit; and posts anonymously at 4chan every now and then. By merely passively eavesdropping on all traffic from and to your IP address, Cloudflare can build a profile that links your real world identity to all your Reddit posts you thought were anonymous; to the naughty threads you visited on 4chan; to the amount of money in your bank account; and to the domains and bitcoin addresses you own. This is something that neither your ISP or any of those individual site owners could ever do, and which might even make the NSA a bit jealous. Now consider what Cloudflare could do on your behalf (and make it look like it was you) if, say, a disgruntled employee was actively out to get you. I'm not at all saying that there is any reason to distrust Cloudflare, but is it not an enormous amount of power to place in the hands of one entity? Even more so than we do with parties like Google or Facebook, which get immensely more scrutinized over it?

astrange 12y ago
4chan's posting API is actually not (as of this very second) behind Cloudflare.

m1keil 12y ago

previously they had your private key, so they could see unencrypted plaintext anyway.