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What? > It has the side effect of sending every domain you visit to the certificate log server. No? It means that if a certificate is to be trusted, it needs

What? > It has the side effect of sending every domain you visit to the certificate log server. No? It means that if a certificate is to be trusted, it needs to enter a public append only log server. It does not "send every domain you visit to CT." The certificate simply has to be in CT before chrome trusts it. CT logs are public, you can (and many do) make archives of it. The idea is simple, if a website is to be _publicly trusted_, it needs to also be publicly logged. You have heavily misunderstood what CT does, and the paradigm of control around it.

salawat 3y ago
Uh huh. And if I log what addresses reach out to me to check for the presence of a particular certificate in the logs? You're not thinking about it hard enough. Your CT's would effectively have to be implemented in a way where everyone had a locally cached copy of the log to check against. That at least shuts down an browsing activity leak vector. If you centralize it, the abuse is a matter of when, not if.
- aaomidi 3y ago
  > Uh huh. And if I log what addresses reach out to me to check for the presence of a particular certificate in the logs? Again, misunderstanding of how it works. Logs are checked using the SCT in the certificate. It's a signed "promise" from the CT that the pre-certificate will eventually be appended to the logs in a few hours since submission. The various root programs monitor to ensure that the promise does in fact happen. Your browser process does *not* reach out to the CT log on its own.
somat 3y ago
Yes but how does your browser trust it? it has to check the cert log. who has the server for the cert log. for chrome this is google. Did you reach a different conclusion from the big table in the wikipeda page where it requires "1 SCT from a google log" ?
- aaomidi 3y ago
  > Did you reach a different conclusion from the big table in the wikipeda page where it requires "1 SCT from a google log" ? I've worked at both Let's Encrypt and Google Trust Services. CT is something I'm intimately familiar with. > it has to check the cert log. No, it does not. > Yes but how does your browser trust it? Your browser ships with a log list: https://source.chromium.org/chromium/chromium/src/+/main:components/certificate_transparency/data/log_list.json https://source.chromium.org/chromium/chromium/src/+/main:com... The public key of the log is included there. It's checked to see if the SCT is signed with the correct public key.
- charcircuit 3y ago
  Chrome hasn't required "1 SCT from a google log" since April 15th 2022
charcircuit 3y ago
To be charitable, he could be talking about the implementation of SCT auditing in Chrome, but it has never uploaded all the sites you visit. There are three possible states: No Safe Browsing protections -> no SCT auditing Default Safe Browsing protections -> SCT auditing logic selects a small proportion of TLS connections and performs a k-anonymous lookup on an SCT. If that privacy-preserving SCT lookup reveals that the SCT is not known to Google but should be, the client uploads the certificate, SCTs, and hostname to Google (but no other information). Enhanced Safe Browsing protections -> SCT auditing logic selects a small proportion of TLS connections and uploads the certificate, SCTs, and hostname to Google (but no other information). https://groups.google.com/a/chromium.org/g/ct-policy/c/FddjjCNIrLo https://groups.google.com/a/chromium.org/g/ct-policy/c/Fddjj...
- aaomidi 3y ago
  Got it. Just for reference for others, SCT Auditing is different from SCT validation. I was talking about the validation side. SCT Auditing basically helps ensure that the logs are keeping their promise by letting the root program (Chrome, and Apple) see what certificates are flowing on the internet and if the merkle tree structure is valid.

salawat 3y ago

Uh huh. And if I log what addresses reach out to me to check for the presence of a particular certificate in the logs? You're not thinking about it hard enough. Your CT's would effectively have to be implemented in a way where everyone had a locally cached copy of the log to check against. That at least shuts down an browsing activity leak vector. If you centralize it, the abuse is a matter of when, not if.

aaomidi 3y ago
> Uh huh. And if I log what addresses reach out to me to check for the presence of a particular certificate in the logs? Again, misunderstanding of how it works. Logs are checked using the SCT in the certificate. It's a signed "promise" from the CT that the pre-certificate will eventually be appended to the logs in a few hours since submission. The various root programs monitor to ensure that the promise does in fact happen. Your browser process does *not* reach out to the CT log on its own.

somat 3y ago

Yes but how does your browser trust it? it has to check the cert log. who has the server for the cert log. for chrome this is google. Did you reach a different conclusion from the big table in the wikipeda page where it requires "1 SCT from a google log" ?

aaomidi 3y ago
> Did you reach a different conclusion from the big table in the wikipeda page where it requires "1 SCT from a google log" ? I've worked at both Let's Encrypt and Google Trust Services. CT is something I'm intimately familiar with. > it has to check the cert log. No, it does not. > Yes but how does your browser trust it? Your browser ships with a log list: https://source.chromium.org/chromium/chromium/src/+/main:components/certificate_transparency/data/log_list.json https://source.chromium.org/chromium/chromium/src/+/main:com... The public key of the log is included there. It's checked to see if the SCT is signed with the correct public key.
charcircuit 3y ago
Chrome hasn't required "1 SCT from a google log" since April 15th 2022

charcircuit 3y ago

To be charitable, he could be talking about the implementation of SCT auditing in Chrome, but it has never uploaded all the sites you visit. There are three possible states: No Safe Browsing protections -> no SCT auditing Default Safe Browsing protections -> SCT auditing logic selects a small proportion of TLS connections and performs a k-anonymous lookup on an SCT. If that privacy-preserving SCT lookup reveals that the SCT is not known to Google but should be, the client uploads the certificate, SCTs, and hostname to Google (but no other information). Enhanced Safe Browsing protections -> SCT auditing logic selects a small proportion of TLS connections and uploads the certificate, SCTs, and hostname to Google (but no other information). https://groups.google.com/a/chromium.org/g/ct-policy/c/FddjjCNIrLo https://groups.google.com/a/chromium.org/g/ct-policy/c/Fddjj...

aaomidi 3y ago
Got it. Just for reference for others, SCT Auditing is different from SCT validation. I was talking about the validation side. SCT Auditing basically helps ensure that the logs are keeping their promise by letting the root program (Chrome, and Apple) see what certificates are flowing on the internet and if the merkle tree structure is valid.