I like the footnote they attached specifically for SHA1. "[3] Google spent 6500 CPU years and 110 GPU years to convince everyone we need to stop using SHA-1 for security critical applications. Also because it was cool." It’s also not preimage. This isn’t even a FIRST preimage attack. That table needs an additional field type: “First non-preimage deliberate crafted collision created”. However, it proves a theory that maybe with some refining *could* turn into a preimage attack. Realistically any hash function *will* have collisions when two items are specifically crafted to collide after expending insane amounts of computing power, money, and… i wonder how much in power they burned for this little stunt.
On Mar 1, 2017, at 9:42 PM, Nick Hilliard <nick@foobar.org> wrote:
James DeVincentis via NANOG wrote:
On top of that, the calculations they did were for a stupidly simple document modification in a type of document where hiding extraneous data is easy. This will get exponentially computationally more expensive the more data you want to mask. It took nine quintillion computations in order to mask a background color change in a PDF.
And again, the main counter-point is being missed. Both the good and bad documents have to be brute forced which largely defeats the purpose. Tthose numbers of computing hours are a brute force. It may be a simplified brute force, but still a brute force.
The hype being generated is causing management at many places to cry exactly what Google wanted, “Wolf! Wolf!”.
The Reaction state table described in https://valerieaurora.org/hash.html appears to be entertainingly accurate.
Nick