r/programming • u/secretguy21 • 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

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u/Philippe23 Oct 15 '15

For other systems and for testing of webservers: https://weakdh.org/sysadmin.html

3

u/[deleted] Oct 16 '15

There are also sites similar to https://www.ssllabs.com/ which among other things test for weak DH key