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benjojo posted 21 Jun 2025 18:29 +0000

Good news, the Tuscolo CT logs are now "Qualified" (meaning that some of your certs are/will soon be using our CT log!!)

The bad news is that by including our new logs in the well known list of CT logs, some stuff now instantly crashes (seemingly because the array of non "Sunlight" (aka next gen) logs is empty).

Impacted things seem to include:

1. 80% of the food delivery app market in Brazil
2. Lots of banks in India
3. Lowes????
4. Basically any app that uses appmattus/certificatetransparency

Suboptimal.

More info:

1. https://github.com/appmattus/certificatetransparency/issues/143
2. https://github.com/google/certificate-transparency-go/issues/1712

benjojo replied 23 Jun 2025 18:57 +0000
in reply to: https://chaos.social/users/waldi/statuses/114733563752009004

@waldi I think the intention here is that you are a banking app and you want to ensure that the TLS certificates that the client is getting are valid as well according to CT (this is not a problem on modern android API versions, but old phones exist etc)

The other obvious (and maybe this is the real reason) upside to using a lib like this, is that TLS MITM Proxy for reverse engineering etc no longer works, because no matter if the TLS Cert root is trusted, it will not have a valid SCT inside of it

waldi@chaos.social replied 23 Jun 2025 19:07 +0000
in reply to: https://benjojo.co.uk/u/benjojo/h/4ZXv9XM2381lJD4bQT

@benjojo No. If you control both sides of the application, you have zero need to tap into WebPKI. This is governed by the CA/Browser Forum, and the name provides information about who the stakeholders are; and this does not include you as random app provider.

So in all the cases, where the provider even refuses to provide a non-app web interface, you are better with a private CA.

And no, SCT checks only work on pre-defined CA, not MITM CA added by hand.