Security in the 20-teens
Posted Feb 1, 2010 18:28 UTC (Mon) by joey
Parent article: Security in the 20-teens
But that nice assumption only holds true for as long as one assumes that
the hash algorithms used to identify commits are not subject to brute-force
collisions. One should be careful about such assumptions when the computing
resources of a national government can be brought to bear. We might still
detect an attempt to exploit a hash collision - but our chances are not as
Of course there is at least one VCS that does not rely on hashing for
security, and instead relies on gpg signatures. The question then becomes:
Is cracking a typical length gpg key within the means of a government?
Hmm.. Hashing is in some ways *better*, because at least with a hash
collision, some random colliding data is nearly certain to be needed. While
if a gpg key is cracked, completely plausible commits could be made.
I outlined some ways that sha1 collisions could be used against git
The second attack mentioned there is not very useful to a government; it's
useful for project members who want to attack a project and cover their
tracks. The first attack could be more useful for a government. Perhaps a
second git repo is not needed; instead their great firewall could replace a
file with a colliding version in passing.
Also, sha1 collisions don't need a government to exploit them. They're
about at the level where a university can muster the equipment to generate a
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