webpki-ccadb: rework TLS distrust after handling #84
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ctz
approved these changes
Nov 13, 2024
Previously we took the aggressive stance of removing a root as soon as it was described in CCADB as having a distrust for TLS after date. There's a good argument[0] that this is more disruptive than helpful. Instead, remove roots with a distrust after date only once that date plus a grace period of 398 days has past. The grace period is equal to the maximum allowable subscriber certificate lifetime based on the CA/Browser Forum's baseline requirements. Since we also want to apply some simple local policy to exclude roots unconditionally a simple block list based on the CCADB SHA256 fingerprint is also added to override the above logic to exclude a root when required. One FP for the GLOBALSIGN 2020 root is added to the block list. We removed this root early because it only has <100 valid certificates in the wild. In this case waiting for the distrust date + grace period would mean keeping the root until Aug 2nd 2025. [0]: https://sslmate.com/blog/post/entrust_distrust_more_disruptive_than_intended
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djc
approved these changes
Nov 13, 2024
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Previously we took the aggressive stance of removing a root as soon as it was described in CCADB as having a distrust for TLS after date. There's a good argument that this is more disruptive than helpful.
Instead, remove roots with a distrust after date only once that date plus a grace period of 398 days has past. The grace period is equal to the maximum allowable subscriber certificate lifetime based on the CA/Browser Forum's baseline requirements.
Since we also want to apply some simple local policy to exclude roots unconditionally a simple block list based on the CCADB SHA256 fingerprint is also added to override the above logic to exclude a root when required.
One FP for the GLOBALSIGN 2020 root is added to the block list. We removed this root early because it only has <100 valid certificates in the wild. In this case waiting for the distrust date + grace period would mean keeping the root until Aug 2nd 2025. Adding it to the block list preserves the early removal decision with the new logic.