Impressive. I wonder the methodology. Algorithmic improvements? More probably just an implementational optimisation. Last RSA record was due to special q sieving methods if I recall well, some 3k core hours.
I hope there’s a theoretical improvement behind the result.
I think this is very likely someone with a box of GPUs since the state of the art (CADO-NFS) doesn't use GPUs at all. Which is crazy since it has a whole lot of linear maths. It's just so old and been so long since the last record no-one's bothered to take another stab at it.
An 8 GPU home lab and a frotier model to GPU-erize it could probably give you the 3x improvement needed over the last attempt on a supercomputer honestly.
So RSA 260 is about 2-3 times harder than RSA 250, which was solved in 2700 core hours in 2020, so it’s probably no algorithmic improvements, just a tweak here and there plus faster hardware.
It's sort of fun to remember the genuine worry in the community around RSA and the (really, really shocking at the time!) progress in factorization leading up to GNFS techniques.
Like, it really looked like everything was going to fall apart. We all rushed to 1024 bit keys, and then to 2048 bit after what felt like a few months. And... maybe even that wouldn't be enough?
And actual history ended up being the boring version: it was absolutely enough, factorization is seemingly settled math at this point, no new techniques have been discovered.
At the end of the day RSA was just fine and no one really needed to bother with ECC and all of its confusing tutorials.
And the ~23 year old 1024 bit key holding my GnuPG box closed is still just fine, cryptographically. (Though the chances of getting hit with a keylogger or other side channel attack over that period are nontrivially high and I suppose I really should rotate it or something).
RSA might be fine mathematically but as a production cryptosystem it’s an unmitigated disaster by modern standards.
Compared to elliptic curves, it is comically easy to build an RSA implementation which is catastrophically broken. Both the number of and subtlety of footguns in RSA are extreme.
Even ignoring that, ECC is far more efficient (in part thanks to smaller key sizes and being able to be done with fixed-width arithmetic rather than needing bignums) and far better suited for embedded devices. Migration has been an enormous win even if you think the security of RSA is fine.
the researchers from the RSA-250 record have publicly claimed that factoring 1024-bit RSA keys is within reach of nation states. Your 1024 bit key is only "fine" because you are a small fry, not because cryptographers think it cannot be attacked. This would be true if you used a (non-standard) RSA-768 parameterization as well, which is easier than what we are talking about on this post.
It's also worth mentioning the main concern for RSA is not GNFS, but something stronger. SOTA RSA attacks (such as GNFS) use "index calculus". You can also use index calculus to attack finite field diffie hellman. In the 2010's, there was remarkable progress in index calculus attacks against finite field DH in the small characteristic case. For example, the current record for binary characteristic finite field DH is ~30k bits (and this is by an academic --- a nation state could definitely do more).
It is not known that similar progress is possible in other cases (such as for RSA). But it's very much possible that factoring is much easier than expected. Simultaneously I wouldn't personally bet money on it, and if that breakthrough happened, there were sufficient warning signs that I would feel justified in saying "told you so" to people trusting RSA.
An 8 GPU home lab and a frotier model to GPU-erize it could probably give you the 3x improvement needed over the last attempt on a supercomputer honestly.
Background: https://en.wikipedia.org/wiki/RSA_Factoring_Challenge
Like, it really looked like everything was going to fall apart. We all rushed to 1024 bit keys, and then to 2048 bit after what felt like a few months. And... maybe even that wouldn't be enough?
And actual history ended up being the boring version: it was absolutely enough, factorization is seemingly settled math at this point, no new techniques have been discovered.
At the end of the day RSA was just fine and no one really needed to bother with ECC and all of its confusing tutorials.
And the ~23 year old 1024 bit key holding my GnuPG box closed is still just fine, cryptographically. (Though the chances of getting hit with a keylogger or other side channel attack over that period are nontrivially high and I suppose I really should rotate it or something).
Compared to elliptic curves, it is comically easy to build an RSA implementation which is catastrophically broken. Both the number of and subtlety of footguns in RSA are extreme.
Even ignoring that, ECC is far more efficient (in part thanks to smaller key sizes and being able to be done with fixed-width arithmetic rather than needing bignums) and far better suited for embedded devices. Migration has been an enormous win even if you think the security of RSA is fine.
It's also worth mentioning the main concern for RSA is not GNFS, but something stronger. SOTA RSA attacks (such as GNFS) use "index calculus". You can also use index calculus to attack finite field diffie hellman. In the 2010's, there was remarkable progress in index calculus attacks against finite field DH in the small characteristic case. For example, the current record for binary characteristic finite field DH is ~30k bits (and this is by an academic --- a nation state could definitely do more).
It is not known that similar progress is possible in other cases (such as for RSA). But it's very much possible that factoring is much easier than expected. Simultaneously I wouldn't personally bet money on it, and if that breakthrough happened, there were sufficient warning signs that I would feel justified in saying "told you so" to people trusting RSA.