package org.bouncycastle.asn1.x9;

import org.bouncycastle.asn1.ASN1Encodable;
import org.bouncycastle.asn1.ASN1EncodableVector;
import org.bouncycastle.asn1.ASN1OctetString;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.DERInteger;
import org.bouncycastle.asn1.DERObject;
import org.bouncycastle.asn1.DERSequence;
import org.bouncycastle.math.ec.ECCurve;
import org.bouncycastle.math.ec.ECPoint;

import java.math.BigInteger;

ASN.1 def for Elliptic-Curve ECParameters structure. See X9.62, for further details.
/** * ASN.1 def for Elliptic-Curve ECParameters structure. See * X9.62, for further details. */
public class X9ECParameters extends ASN1Encodable implements X9ObjectIdentifiers { private static final BigInteger ONE = BigInteger.valueOf(1); private X9FieldID fieldID; private ECCurve curve; private ECPoint g; private BigInteger n; private BigInteger h; private byte[] seed; public X9ECParameters( ASN1Sequence seq) { if (!(seq.getObjectAt(0) instanceof DERInteger) || !((DERInteger)seq.getObjectAt(0)).getValue().equals(ONE)) { throw new IllegalArgumentException("bad version in X9ECParameters"); } X9Curve x9c = new X9Curve( new X9FieldID((ASN1Sequence)seq.getObjectAt(1)), (ASN1Sequence)seq.getObjectAt(2)); this.curve = x9c.getCurve(); this.g = new X9ECPoint(curve, (ASN1OctetString)seq.getObjectAt(3)).getPoint(); this.n = ((DERInteger)seq.getObjectAt(4)).getValue(); this.seed = x9c.getSeed(); if (seq.size() == 6) { this.h = ((DERInteger)seq.getObjectAt(5)).getValue(); } } public X9ECParameters( ECCurve curve, ECPoint g, BigInteger n) { this(curve, g, n, ONE, null); } public X9ECParameters( ECCurve curve, ECPoint g, BigInteger n, BigInteger h) { this(curve, g, n, h, null); } public X9ECParameters( ECCurve curve, ECPoint g, BigInteger n, BigInteger h, byte[] seed) { this.curve = curve; this.g = g; this.n = n; this.h = h; this.seed = seed; if (curve instanceof ECCurve.Fp) { this.fieldID = new X9FieldID(((ECCurve.Fp)curve).getQ()); } else { if (curve instanceof ECCurve.F2m) { ECCurve.F2m curveF2m = (ECCurve.F2m)curve; this.fieldID = new X9FieldID(curveF2m.getM(), curveF2m.getK1(), curveF2m.getK2(), curveF2m.getK3()); } } } public ECCurve getCurve() { return curve; } public ECPoint getG() { return g; } public BigInteger getN() { return n; } public BigInteger getH() { if (h == null) { return ONE; // TODO - this should be calculated, it will cause issues with custom curves. } return h; } public byte[] getSeed() { return seed; }
Produce an object suitable for an ASN1OutputStream.
 ECParameters ::= SEQUENCE {
     version         INTEGER { ecpVer1(1) } (ecpVer1),
     fieldID         FieldID {{FieldTypes}},
     curve           X9Curve,
     base            X9ECPoint,
     order           INTEGER,
     cofactor        INTEGER OPTIONAL
 }
/** * Produce an object suitable for an ASN1OutputStream. * <pre> * ECParameters ::= SEQUENCE { * version INTEGER { ecpVer1(1) } (ecpVer1), * fieldID FieldID {{FieldTypes}}, * curve X9Curve, * base X9ECPoint, * order INTEGER, * cofactor INTEGER OPTIONAL * } * </pre> */
public DERObject toASN1Object() { ASN1EncodableVector v = new ASN1EncodableVector(); v.add(new DERInteger(1)); v.add(fieldID); v.add(new X9Curve(curve, seed)); v.add(new X9ECPoint(g)); v.add(new DERInteger(n)); if (h != null) { v.add(new DERInteger(h)); } return new DERSequence(v); } }