DiffieHellman Key Exchange
Motivation for Key Exchange Algorithm
The fastest encryption schemes are symmetric encryption schemes. In order to use these,
the two communicators (Alice & Bob) would have to meet in a secure location. BUT, this
sort of defeats the purpose, because their whole goal is to communicate when securely
when they aren't in the same place. A modern day example of why it would be useful to
exchange a key without meeting deals with an online purchase. You are making the
purchase online so that you DON'T have to go to the store to meet with the vendor. So,
you don't really want to go to the store to just exchange a secret key either. You want to
be able to do that from the comfort of your own home.
Thus, that is the underlying problem: how do two users exchange a secret key without a
secure communication channel?
The first solution to this problem was the DiffieHellman Key Exchange. What's
interesting about this algorithm is that neither user actually gets to choose the key. But, at
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 Fall '06
 Guha
 Cryptography, Sort, Prime number, Alice, discrete log problem

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