[[!comment format=mdwn
 username="joey"
 subject="""comment 8"""
 date="2023-11-30T20:43:53Z"
 content="""
I think Ilya Shlyakhter gets to a fundamental problem in his comment above.
Any way that git-annex stores data about an alternate key that is recorded
in git, allows anyone to spoof bad data.

For example, if I have a SHA256 key stored in git-annex, it would be a bad
security hole if I fetched from Ilya's repository and suddenly git-annex
was willing to accept some MD5 key as being the same content as my SHA256
key. Even if the two keys had the same content currently, that MD5 key can
be collision attacked later.

So there would need to be a direction in which key upgrades were allowed.
Which is fine for `WORM -> SHA256`, but less clear for `SHA1 -> SHA256`
and much less clear for other pairs of modern hashes.
"""]]
