Re:How is NSA breaking so much crypto? (2015)
by agwa on Sunday December 18, 2016 @12:15PM
(#13206547)
No, because there's a simple solution to state actors doing massive computations: make the parameters so large (2048 bits in the case of DH) that the computations are infeasible.
DH precomputation attacks are only a problem with smaller prime sizes (e.g. 1024 bits). Experts have always known to avoid small parameters, but developers copy-and-pasted them into their code without knowing they were bad.
Re:How is NSA breaking so much crypto? (2015)
by Laforet on Sunday December 18, 2016 @02:28PM
(#13207143)
This is kind of parallels what happened with MD5 fingerprints in X509 certificates: for years the writing was on the wall that MD5 collision was imminent with better algorithm and more computing power, yet it took a number of practical exploits by individual researchers to convince the industry that MD5 has to go away. One good thing to have come out of it was that we really learned about the importance to future proof our crypto and the phase-out of SHA1 was carried out a lot more elegantly.
Similarly, it is expected now that state level actors can already break 1024 bit RSA and 128 bit symmetric ciphers may be the next thing to fall. Hence their use should be avoided wherever possible.
Re:How is NSA breaking so much crypto? (2015)
by javajosh on Monday December 19, 2016 @10:41AM
(#13212050)
That's a very good point, but I don't think it invalidates the "biodiversity" argument. It's a different kind of defense, but it is a defense. For example, if there is a breakthrough in prime factorization, then heterogenous implementations may be the only security left to us.
Even if it takes a day for a kid at the NSA to break my custom crypto, that's better than if I use homogenous crypto that takes 2ms to break. And if everyone is using bad custom crypto, that's a lot of time needed to break each one individually. The argument is very close to that against monolithic grain cultures that, while they have the best yields, resisitance to pests, and so forth, they are also more vulnerable to as-yet-unknown diseases. Bio-diversity is a good defense against that contingency.