<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><br><div><div>On Jan 31, 2014, at 10:50 AM, Paulo S. L. M. Barreto <<a href="mailto:pbarreto@larc.usp.br">pbarreto@larc.usp.br</a>> wrote:</div><blockquote type="cite"><div style="font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;">You convinced me. If you convince Diego as well, we'll have fun redesigning<br>the curve-finding script ;-) (actually I wasn't quite happy with them either,<br>since they don't adopt the more efficient (-1)-twist for Edwards curves)<br></div></blockquote></div><br><div>Heh, sorry to cause trouble.</div><div><br></div><div>+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.</div><div><br></div><div>Cheers,</div><div>— Mike</div></body></html>