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Diffie-Hellman for the Layman (borisreitman.medium.com)
86 points by EntICOnc 13 days ago | hide | past | favorite | 19 comments





I skimmed the article and it seems to be a description of a web tool that uses DH or something like it so that two people can come up with a common password without exchanging the password. However, it doesn’t explain the DH algorithm. I suggest re-titling the article for better accuracy.

To be fair the title doesn't mention "Algorithm".

That is not fair.

So we should take it refers to actual persons?

If you are looking for an intuitive, visual explanation of the Diffie-Hellman key exchange method I highly recommend watching the video from Computerphile [1] where the color-mixing analogy [2] is put into practice.

[1] - https://www.youtube.com/watch?v=NmM9HA2MQGI

[2] - https://en.wikipedia.org/wiki/Diffie%E2%80%93Hellman_key_exc...


Here is another video from "Art of the Problem" that uses the same analogy that really helped me understand this better:

https://www.youtube.com/watch?v=YEBfamv-_do


I think the color mixing analogy is probably the best. Probably since it's an actual implementation of Diffie-Hellman. The fact that it is so generic is pretty cool.

I also like the prime number factorization explanation. It's a little harder to understand, but it's actually used in RSA which is pretty cool.


Easily the best layman's explanation out there. Really made it click in my head. I show this to everyone.


If anyone is looking for an actual explanation of Diffie-Hellman for the layman, here is my 1-page blog about two kids implementing it on a calculator.

https://blog.bonner.is/schoolyard-example-of-the-diffie-hell...


That was a very nice explanation, thank you. Side notes regarding your blog: The "subscribe to" text towards the bottom is hard to read against its background. Also, the preview of the "What problem does Polymer solve?" article (also towards the bottom) has raw HTML in it.

The math behind DH is pretty simple and really interesting.

Yes. Though having heard of modulo arithmetic before helps a lot. So eg simple enough for your typical HN crowd.

There's also an interesting public key encryption system you can build on top of DH called ElGamal. https://en.wikipedia.org/wiki/ElGamal_encryption

What makes ElGamal so interesting, is that it's probabilistic and that you can easily prove its semantic security (from relatively straightforward assumptions), and more importantly 'indistinguishability under Chosen Plaintext Attack' (https://en.wikipedia.org/wiki/Ciphertext_indistinguishabilit...)

Ie even if the attacker can guess your plaintext and knows the public key, they can't be sure that they guessed right.



Hmm his "Web tool" is not working. https://borisretiman.com/privacy.html, don't think think the domain is working.

It's a nice article but it's not for lay people.

For "lay" people, Whitfield Diffie talked at the Mathematical Sciences Research Institute in 1996 on the politics of communication, with Tim Berners-Lee in the audience.

This was one of the best talks I ever attended. The other was Lynn Conway describing how she applied her study of anthropology to initiating a revolution in VLSI design. I did not know or appreciate at the time how being a trans woman also informed her understanding of the revolutionary process.


Do you know if the Lynn Conway talk was recorded and available online?

I doubt it. This was mid-80's at Columbia. I'd love to watch it again if you can find it!



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