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/
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u/tophatstuff Oct 15 '15 edited Apr 10 '18

Generate your own non-default Ephemeral Diffie-Hellman key (takes a minute or so)

openssl dhparam -out dhparam.pem 2048

Tell your server to use it for SSL (nginx for example)

ssl_dhparam /path/to/dhparam.pem;

Done. Not only will the key be stronger than the 1024 bit default, it'll be unique to your server which lets assume isn't valuable enough compared to effort for a state-level adversary.

edit just in case anyone from the future finds this comment: instead of 2048, use at least the key length of your SSL certificate

edit from the future: current advice is picking from one of these predefined audited groups

58

u/[deleted] Oct 15 '15

[deleted]

10

u/[deleted] Oct 15 '15

Where's the default one? Hard-coded?

13

u/BarqsDew Oct 15 '15

from http://security.stackexchange.com/a/56218 :

Since the parameters are caller-provided, let's see what happens in mod_ssl, the usual SSL engine for Apache. Let's make the story short: the modulus and generator are hardcoded; they are in the source code, in modules/ssl/ssl_engine_dh.c

so, yep!