Java tutorial
package org.bouncycastle.asn1.x9; import java.util.Enumeration; import java.util.Vector; import org.bouncycastle.asn1.ASN1ObjectIdentifier; import org.bouncycastle.asn1.anssi.ANSSINamedCurves; import org.bouncycastle.asn1.cryptopro.ECGOST3410NamedCurves; import org.bouncycastle.asn1.gm.GMNamedCurves; import org.bouncycastle.asn1.nist.NISTNamedCurves; import org.bouncycastle.asn1.sec.SECNamedCurves; import org.bouncycastle.asn1.teletrust.TeleTrusTNamedCurves; import org.bouncycastle.crypto.ec.CustomNamedCurves; import org.bouncycastle.crypto.params.ECDomainParameters; /** * A general class that reads all X9.62 style EC curve tables. */ public class ECNamedCurveTable { /** * return a X9ECParameters object 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 an X9ECParameters object or null if the curve is not available. */ public static X9ECParameters getByName(String name) { X9ECParameters ecP = X962NamedCurves.getByName(name); if (ecP == null) { ecP = SECNamedCurves.getByName(name); } if (ecP == null) { ecP = NISTNamedCurves.getByName(name); } if (ecP == null) { ecP = TeleTrusTNamedCurves.getByName(name); } if (ecP == null) { ecP = ANSSINamedCurves.getByName(name); } if (ecP == null) { ecP = fromDomainParameters(ECGOST3410NamedCurves.getByName(name)); } if (ecP == null) { ecP = GMNamedCurves.getByName(name); } return ecP; } /** * return the object identifier signified by the passed in name. Null * if there is no object identifier associated with name. * * @return the object identifier associated with name, if present. */ public static ASN1ObjectIdentifier getOID(String name) { ASN1ObjectIdentifier oid = X962NamedCurves.getOID(name); if (oid == null) { oid = SECNamedCurves.getOID(name); } if (oid == null) { oid = NISTNamedCurves.getOID(name); } if (oid == null) { oid = TeleTrusTNamedCurves.getOID(name); } if (oid == null) { oid = ANSSINamedCurves.getOID(name); } if (oid == null) { oid = ECGOST3410NamedCurves.getOID(name); } if (oid == null) { oid = GMNamedCurves.getOID(name); } return oid; } /** * return a X9ECParameters object representing the passed in named * curve. * * @param oid the object id of the curve requested * @return a standard name for the curve. */ public static String getName(ASN1ObjectIdentifier oid) { String name = X962NamedCurves.getName(oid); if (name == null) { name = SECNamedCurves.getName(oid); } if (name == null) { name = NISTNamedCurves.getName(oid); } if (name == null) { name = TeleTrusTNamedCurves.getName(oid); } if (name == null) { name = ANSSINamedCurves.getName(oid); } if (name == null) { name = ECGOST3410NamedCurves.getName(oid); } if (name == null) { name = GMNamedCurves.getName(oid); } if (name == null) { name = CustomNamedCurves.getName(oid); } return name; } /** * return a X9ECParameters object representing the passed in named * curve. * * @param oid the object id of the curve requested * @return an X9ECParameters object or null if the curve is not available. */ public static X9ECParameters getByOID(ASN1ObjectIdentifier oid) { X9ECParameters ecP = X962NamedCurves.getByOID(oid); if (ecP == null) { ecP = SECNamedCurves.getByOID(oid); } // NOTE: All the NIST curves are currently from SEC, so no point in redundant OID lookup if (ecP == null) { ecP = TeleTrusTNamedCurves.getByOID(oid); } if (ecP == null) { ecP = ANSSINamedCurves.getByOID(oid); } if (ecP == null) { ecP = fromDomainParameters(ECGOST3410NamedCurves.getByOID(oid)); } if (ecP == null) { ecP = GMNamedCurves.getByOID(oid); } return ecP; } /** * return an enumeration of the names of the available curves. * * @return an enumeration of the names of the available curves. */ public static Enumeration getNames() { Vector v = new Vector(); addEnumeration(v, X962NamedCurves.getNames()); addEnumeration(v, SECNamedCurves.getNames()); addEnumeration(v, NISTNamedCurves.getNames()); addEnumeration(v, TeleTrusTNamedCurves.getNames()); addEnumeration(v, ANSSINamedCurves.getNames()); addEnumeration(v, ECGOST3410NamedCurves.getNames()); addEnumeration(v, GMNamedCurves.getNames()); return v.elements(); } private static void addEnumeration(Vector v, Enumeration e) { while (e.hasMoreElements()) { v.addElement(e.nextElement()); } } private static X9ECParameters fromDomainParameters(ECDomainParameters dp) { return dp == null ? null : new X9ECParameters(dp.getCurve(), new X9ECPoint(dp.getG(), false), dp.getN(), dp.getH(), dp.getSeed()); } }