1503352 - generate signed tree heads for the binary transparency information created per release

Status: RESOLVED INCOMPLETE

(Release Engineering :: Release Automation: Other, enhancement)

Description

[Dana Keeler (she/her) (use needinfo) [:keeler] (on leave)]

In bug 1342974, we added code that generates binary transparency information per release. However, while that information does include the tree head hash, it doesn't include a signed tree head.

There is an argument to be made that we don't need to verify a signed tree head because the tree head hash will be put into a certificate (in the subject alternative names field as something like "hashhalf1.hashhalf2.version.fx-trans.net") issued by a CA that we can (and should) verify (both for being correctly signed and potentially for being properly disclosed in a CT log). However, having a (few) key(s) that we trust gives us a way to protect against an attacker tricking a CA into issuing a certificate for a domain-name-ified hash of a merkle tree that they created. (CT doesn't prevent misissuance - it gives us a way to detect it.)

The structure of a signed tree head is in https://tools.ietf.org/html/draft-ietf-trans-rfc6962-bis-28#section-4.10

Comment 1

[Julien Cristau [:jcristau]]

As far as I can tell this effort died down some years ago; closing.