Re:How is NSA breaking so much crypto? (2015)
by marcosdumay on Saturday December 17, 2016 @12:46PM
(#13201571)
> Are good primes that hard to come by?
My laptop takes around 2 minutes to get a pair of 4k bits primes for DH parameters.
The problem is that people want their installers to be instantaneous. Those 2 minutes are too long.
Re:How is NSA breaking so much crypto? (2015)
by alkonaut on Saturday December 17, 2016 @02:20PM
(#13201975)
A popular app could ship with 100 different primes pre baked and pick one at random? Not perfect but 100x better than having one prime.
Re:How is NSA breaking so much crypto? (2015)
by marcosdumay on Saturday December 17, 2016 @04:51PM
(#13202881)
If those primes are compromised, 100 of them are still useless.
Re:How is NSA breaking so much crypto? (2015)
by alkonaut on Sunday December 18, 2016 @03:54AM
(#13204975)
Yes that's only useful under the original assumption of the article: that a state level actor must use a nontrivial part of its budget to factor one prime. The back of the envelope calculations if they did classical factorization is that one or a few 1024bit primes were possible but 100 were not. Of course next year they will have twice the CPU time, or a better quantum computer, so it's a short term win.
It seems like a massive waste of energy and money to crack a few primes if the advantage you gain can be erased so quickly?
I agree it seems like writing custom bad crypto is way better than good crypto that can be broken in bulk. (Using both kinds together seems clever). A good analyst can likely break my homemade crypto in twenty minutes, but that's orders of magnitude better than using a compromised strong crypto!
Another question: Are good primes that hard to come by? Shouldn't apps generate new primes instead of re-using old ones?
Last question: are there good cryptos that aren't sensitive to a state level actor that can factor primes in linear time?