3 ms·
Think about any software updates you do (Windows Update, apt, yum, etc). All these systems rely on distributing a cryptographic ally signed manifest of what eac
by dsl 9y ago
Think about any software updates you do (Windows Update, apt, yum, etc). All these systems rely on distributing a cryptographic ally signed manifest of what each files hash should be.
If you can forge the hash of a file, or the signature on that manifest, there are hundreds of different ways you can easily replace one file for another in transit over the internet.
- ethbro 9y agoI'd guess something like Quantum Insert + targeting unprotected connections. Which I'd imagine there are still a lot of out there (circa pre-2000). I'd be curious if there's any older network gear that provides a hash-based rather than connection-based security model. It seems like the thing that might have seemed like a good idea to a military 40 years ago.
- tptacek 9y agoWe're also not a supercomputer advance away from breaking SHA2. There are hash-designing cryptographers who believe we may never break SHA2 with conventional computers.
- schoen 9y agoThat's a very different attack than I was looking for; you've described a second preimage attack, which would be considered a fundamental weakness of the hash. I was looking for a protocol where a comparatively small amount of signed data (let's say less than 90 bits) is kept secret, but can potentially be brute-forced on an appropriate supercomputer.