So this reading assigment is the discrete log equivalent of the reading on treaty verification and non-repudiation for RSA. Cool applications of a cipher system. The reading seemed to be going off on three topics until at the end when Diffie-Hellman and ElGamal were shown to be similar.
ElGamal works because (a^-k)(m)(a^k)=m in the ring of integers modulo a prime p. But I remember that that is not always the case for every group. I think that non-abelian groups are the ones for which (a^-k)(m)(a^k)=m is not true. But I need to look that up again.
Diffie-Hellman is pretty slick. Alics picks an x and Bob picks a y and each sends the other a raised to their integer mod p, then they raise the number they recieved to their own integer's power. then both end up with the same number to use as a key, even though Eve only knows a^x and a^y. Eve can't find a^(xy) because that would solve the discrete log problem. Really clever.
Have to go over why this is the same as the ElGamal procedure though. Suppose that seeing the lecture tomorrow will make the linkage more clear.
Dr. Doud kept saying that he wanted to show us "Russian Peasant" multiplication, but lamented that he did not have the time to show us. If you have time that would be neat to see.
Hope that the conference you attended went well. See you tomorrow.
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