It wasn’t. The person that posted the factorization has nothing to do with Anthropic, and has for many years held the leaderboard on GPU-hours applied to factorization and prime search problems. He’s not yet on record as to how this one was done (probably waiting for publication), but there is no reason at all to assume any LLM was involved.

I heard it was a lucky guess

Seems unlikely given claude would not really be effective for this type of problem.

Why not? Claude has already shown it can automate mathematics and it can automate programming and running programs (including renting the servers).

Because there is nothing not already automated here. RSA will either be cracked because some assumption about prime numbers doesn’t hold or because we throw more and more brute force on it.

And if it were the former it wouldn’t be the “next” in line that would be cracked…

You don't have to have RSA be broken in order to get a competitive advantage over other people searching. You just need Claud to find software optimization that got overlooked or something from number theory to come up with better candidates to guess.

True, but if that happened, i think that would be the headline, not RSA-260 was factorized.