MATH: Brands cash, Hal's posts

[Hal]

Karl Barrus <klbarrus at owlnet.rice.edu> writes a very nice set
of examples of some of the discrete-log protocols using actual numbers.

I did leave one thing out:

>* Schnorr identification protocol
>[...]
>> 3.  Paul calculates r = cx+w and sends that to Vicki.

>Paul calculates r = 561 * 555 + 200 = 311555.

This works, but it will be more efficient to take r mod the order of g,
which would be n-1 in this case.  The same thing applies to all of the 
other places where we multiply and add exponents.

>> 4.  Vicki confirms that g^r = (GX^c)*GW.  Both should be g^(cx+w).

This should still be true with r = cx+w mod (n-1).

I departed from the nice step-by-step description for the actual cash
protocols because they are so complicated and I wanted to explain it as
I went.  If Karl gets far enough to try doing that it would probably be
worthwhile to rewrite that portion first.

Hal