mirrors/git-annex
2
0
Fork 0
Code Issues Pull requests Projects Releases Packages 1 Wiki Activity Actions

update

Browse source
This commit is contained in:
Joey Hess 2017-02-24 01:21:54 -04:00
parent 102e04b30c
commit 44b9ac41a4
No known key found for this signature in database
GPG key ID: C910D9222512E3C7
1 changed files with 13 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

15
doc/todo/sha1_collision_embedding_in_git-annex_keys.mdwn
View file

@ -23,10 +23,21 @@ is enabled)
A few other potential problems: A few other potential problems:
* `*E` backends could embed sha1 collision data in a long filename * `*E` backends could embed sha1 collision data in a long filename
extension. It might be worth limiting the length extension in a key.
Impact is limited, because even if an attacker does this, the key also
contains the checksum (eg SHA2) of the annexed data. The current SHA1
attack is only a prefix attack; it does not allow creating two colliding
keys that contain two different SHA2 checksums. That would need a
preimage attack to be feasible.
It might be worth limiting the length
of an extension allowed in such a key to the longest such extension of an extension allowed in such a key to the longest such extension
git-annex has ever supported (probably < 20 bytes or so), which would git-annex has ever supported (probably < 20 bytes or so), which would
be less than the size of the data needed for current SHA1 collision attacks. be less than the size of the data needed for current SHA1 collision
attacks. Presumably aa preimage attack would need a similar amount of
data.
* It might be possible to embed colliding data in a specially constructed * It might be possible to embed colliding data in a specially constructed
key name with an extra field in it, eg "SHA256-cXXXXXXXXXXXXXXX-...". key name with an extra field in it, eg "SHA256-cXXXXXXXXXXXXXXX-...".
Need to review the code and see if such extra fields are allowed. Need to review the code and see if such extra fields are allowed.