* init: When annex.securehashesonly has been set with git-annex config,
copy that value to the annex.securehashesonly git config.
* config --set: As well as setting value in git-annex branch,
set local gitconfig. This is needed especially for
annex.securehashesonly, which is read only from local gitconfig and not
the git-annex branch.
doc/todo/sha1_collision_embedding_in_git-annex_keys.mdwn has the
rationalle for doing it this way. There's no perfect solution; this
seems to be the least-bad one.
This commit was supported by the NSF-funded DataLad project.
Yesterday's SHA1 collision attack could be used to generate eg:
SHA256-sfoo--whatever.good
SHA256-sfoo--whatever.bad
Such that they collide. A repository with the good one could have the
bad one swapped in and signed commits would still verify.
I've already mitigated this.
I am not happy that I had to put backend-specific code in file2key. But
it would be very difficult to avoid this layering violation.
Most of the time, when parsing a Key from a symlink target, git-annex
never looks up its Backend at all, so adding this check to a method of
the Backend object would not work.
The Key could be made to contain the appropriate
Backend, but since Backend is parameterized on an "a" that is fixed to
the Annex monad later, that would need Key to change to "Key a".
The only way to clean this up that I can see would be to have the Key
contain a LowlevelBackend, and put the validation in LowlevelBackend.
Perhaps later, but that would be an extensive change, so let's not do
it in this commit which may want to cherry-pick to backports.
This commit was sponsored by Ethan Aubin.
