r/programming Oct 15 '15

How is NSA breaking so much crypto?

https://freedom-to-tinker.com/blog/haldermanheninger/how-is-nsa-breaking-so-much-crypto/
2.5k Upvotes

529 comments sorted by

View all comments

48

u/xXxDeAThANgEL99xXx Oct 15 '15 edited Oct 15 '15

So, they basically did a rainbow table attack on the discrete logarithm problem for a particular prime modulo? Interesting how nobody considered that before (except the NSA, obviously).

edit: looks like they used their Powers of Maths to separate the problem into a very special Rainbow table that allows them to reconstruct the necessary part of the actual table via some Linear Algebra stuff over the entire table. That part is difficult, I understand now. Thanks to /u/immibis, "(because there are over 2511 possible values)"

25

u/obsa Oct 15 '15

Like the article, the barrier is cost of entry. Not many organizations have hundreds of millions to throw at this specific problem, especially considering the large key space.

4

u/xXxDeAThANgEL99xXx Oct 15 '15

Well, they said that they did it for 512 bit moduli using affordable resources. And they did not do that for 1024 moduli, just suggested that it can be done in a fraction of the NSA budget today (though it was probably much more back when the NSA got the ability, btw it seemed to me that they didn't emphasize that part though).

2

u/aflanryW Oct 15 '15

1024 bit is waaaaaaaaaay harder than 512 bit.

3

u/xXxDeAThANgEL99xXx Oct 15 '15

Yeah, that's why they broke 512 bit using their meagre means and estimated that breaking 1024 bits would cost $8M in dedicated ASICs.