SHA-1 Cracked after 20 Years

[FrgMstr]

Secure Hash Algorithm 1 has finally been cracked. That said, it is not exactly something easy to do and requires some expensive resources, but we can be sure that someone nasty has those resources available. You can read up on this at the Google Security Blog.

Today, more than 20 years after of SHA-1 was first introduced, we are announcing the first practical technique for generating a collision. This represents the culmination of two years of research that sprung from a collaboration between the CWI Institute in Amsterdam and Google. We’ve summarized how we went about generating a collision below. As a proof of the attack, we are releasing two PDFs that have identical SHA-1 hashes but different content.

So what kind of resources are needed to crack SHA-1? Google tells us that over 6,600 years of CPU computation time are needed to complete the crack. So unless you have a data center at your fingertips, or have access in to multiple CPUs at multiple datacenters, you will not be able to play with this yourself. This all said, SHA-1 has pretty much gone the way of the dinosaur, giving way to SHA-3 and SHA-256. So all in all, this is good news and given that the specifics will be released in a few months, but if you rely on SHA-1, now you have a very good reason to move to more modern cryptographic hash functions.

 

[lironmiron]

For pretty much any country, from North Korea up, 100 GPUs would be a negligible expense.

 

[Daeron]

110 GPU years...that would be 100% load on 110 GPUs for a solid year with no failures...

That is also in addition to the 6500 CPU years needed...

Cloud is predominately the only platform to accomplish this with in any resemblance of cost effectiveness, and all of that only provides a SINGLE hash collision.

As a POC, yup, it's on the shelf with DES and MD5. The reality is that we are just barely computationally able to accomplish the feat. As Moore's Law applies to this as well, in a few years, you'll be able to do it on your smart phone in a minute or 2...

 

[Burticus]

SHA 1 is ancient, by technology terms. That it took this long means it was pretty good to begin with. Close your eyes and think about what computer you were using in 1997. Pentium 200 MMX? Yeah. We now have like 40x that power in our smartphones.

 

[Sycraft]

It's also not quite as big a deal as people make it out to be. This works only if you can arbitrarily pad the file in question with data. So for something like PDF where you can stick a bunch of shit in metadata, it is feasible. However it wouldn't work for an X.509 certificate because adding on extra stuff would make it invalid.

That said it is still a good demonstration of why things need to move over to SHA-2, if they haven't already.