A few years ago, while attending a "Computer Systems and Networks Security" class, I was talking with a friend of mine. We said to each other: "There's no way in hell that two principals can exchange a key without a pre-shared key of some sort".

A few minutes later, our professor introduced us to the Diffie-Hellman method for key exchange.

As you may know, the Diffie-Hellman method allows just that, two parties can share a secret key without any prior knowledge of each other. That secret key can then be used to encrypt data or whatever anyone wants to do with a secret key.

This made me think. There we were thinking a problem was plain impossible and a few minutes later we saw a solution that seemed way too simple for such a hard problem. But it works.

Whitfield Diffie and Martin Hellman found an "impossible" problem and transformed it in a problem with a solution. They didn't say "That's just impossible, let's just solve other problem".

From that day on, when I find an "impossible" problem I remember the day I heard about the D-H method and I think that maybe, just maybe, there's a solution hidden somewhere. It motivates me to dig deeper, try harder and never dismiss a problem as "impossible".



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