/**
* return a parameter spec representing the passed in named curve. The routine returns null if the
* curve is not present.
*
* @param name the name of the curve requested
* @return a parameter spec for the curve, null if it is not available.
*/
public static ECNamedCurveParameterSpec getParameterSpec(String name) {
X9ECParameters ecP = org.spongycastle.crypto.ec.CustomNamedCurves.getByName(name);
if (ecP == null) {
try {
ecP = org.spongycastle.crypto.ec.CustomNamedCurves.getByOID(new ASN1ObjectIdentifier(name));
} catch (IllegalArgumentException e) {
// ignore - not an oid
}
if (ecP == null) {
ecP = org.spongycastle.asn1.x9.ECNamedCurveTable.getByName(name);
if (ecP == null) {
try {
ecP =
org.spongycastle.asn1.x9.ECNamedCurveTable.getByOID(new ASN1ObjectIdentifier(name));
} catch (IllegalArgumentException e) {
// ignore - not an oid
}
}
}
}
if (ecP == null) {
return null;
}
return new ECNamedCurveParameterSpec(
name, ecP.getCurve(), ecP.getG(), ecP.getN(), ecP.getH(), ecP.getSeed());
}
static {
// Tell Bouncy Castle to precompute data that's needed during secp256k1 calculations. Increasing
// the width
// number makes calculations faster, but at a cost of extra memory usage and with decreasing
// returns. 12 was
// picked after consulting with the BC team.
FixedPointUtil.precompute(CURVE_PARAMS.getG(), 12);
CURVE =
new ECDomainParameters(
CURVE_PARAMS.getCurve(), CURVE_PARAMS.getG(), CURVE_PARAMS.getN(), CURVE_PARAMS.getH());
HALF_CURVE_ORDER = CURVE_PARAMS.getN().shiftRight(1);
}