[Cryptography] Why is ECC secure?

[Viktor Dukhovni]

On Fri, Aug 14, 2015 at 12:15:00PM -0700, Bill Cox wrote:

>   Addition rule: 1/(1/a + 1/b), or 0 if a == 0, b == 0, or 1/a + 1/b == 0

The neutral element is infinity, not 0 (makes sense in terms of
the parallel resistor model).

As for cryptography: point doubling gives: a + a -> 1/(1/a + 1/a)
= a/2.  And (a/n + a) = 1/(n/a + 1/a) = a/(n+1)).

So scalar multiplication is just division.  Not especially useful
for DH! :-)

-- 
	Viktor.