On Jan 31, 2014, at 10:50 AM, Paulo S. L. M. Barreto <[email protected]>
wrote:
> You convinced me. If you convince Diego as well, we'll have fun redesigning
> the curve-finding script ;-) (actually I wasn't quite happy with them either,
> since they don't adopt the more efficient (-1)-twist for Edwards curves)
Heh, sorry to cause trouble.
+1 vs -1 doesn’t matter that much. They’re isomorphic over 1 mod 4 fields, and
isogenous over 3 mod 4 fields. We’ve been spec’ing them as +1 at least for 3
mod 4 fields, so that arithmetic is complete, and leaving the isogenous curve
as an implementation trick. But whatever the case is, you’ll find basically
the same curves whichever sign you choose.
Cheers,
— Mike
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