6 ms·

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.

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.