19 lines
999 B
Markdown
19 lines
999 B
Markdown
[The first SHA1 collision](https://shattered.io/) was announced today,
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produced by an identical-prefix collision attack.
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After looking into it all day, it does not appear to impact git's security
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immediately, except for targeted attacks against specific projects by
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very wealthy attackers. But we're well past the time when it seemed ok that git
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uses SHA1. If this gets improved into a chosen-prefix collision
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attack, git will start to be rather insecure.
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Projects that store binary files in git, that might be worth $100k for an
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attacker to backdoor **should** be concerned by the SHA1 collisions.
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A good example of such a project is
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<git://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git>.
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Using git-annex (with a suitable backend like SHA256) and signed commits
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together is a good way to secure such repositories.
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git-annex's SHA1 backend is already documented as only being
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"for those who want a checksum but are not concerned about
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security", so no changes needed here.
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