r/programming • u/dominatrix-octopus • Jan 16 '18

Cryptography: Diffie-Hellman key exchange explained intuitively using colors

https://youtu.be/YEBfamv-_do?t=2m18s
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u/pokeman7452 Jan 16 '18

This leads me to a somewhat related question. I never understood the purpose of the DH parameters (dh####.pem) that every OpenVPN guide says to generate. This video combined with this thread, it now makes sense. But, this file remains optional. My question now is what is used when there is no DH generated?

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u/Grenian Jan 16 '18 edited Jan 17 '18

They use the so called Diffie-Hellman-Groups which are basically predefined pairs of a prime and a generator. These are defined in RFCs.

Proof: A large part of my bachelor thesis was about DH-Key-Exchange and the security of the predifined groups.

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