I don't know the answer, but since the vulnerability is because there is some structure in the chosen primes, you don't need to check all possibilities between

I don't know the answer, but since the vulnerability is because there is some structure in the chosen primes, you don't need to check all possibilities between 2^1024 and 2^2048. Only a known subset (i.e. a subset which is likely related to the 20,000/38 ratio)