[curves] The great debate over point formats (Mike Hamburg)

[Paulo S. L. M. Barreto]

On Fri Jan 31 00:07:44 PST 2014, Mike Hamburg wrote:

> We could start with x^2 + y^2 = 1 - 14666 x^2 y^2 mod 2^192-2^64-1.
> The isogenous curve — y^2 = x^3 + 58666*x^2 + x — is isomorphic to
> y^2 = x^3 - 3*x + 6047900113480193987160910265022055632294672911518856488260.

I think we discussed this one in private already. Let u := sqrt(-d). Then 2*(u
- 1)/(u + 1) is not a square, and the Elligator injective map is undefined.

Paulo.