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Viewing changes to src/org/bouncycastle/asn1/x9/X9ECParameters.java

  • Committer: Brian Thomason
  • Date: 2011-12-20 17:20:32 UTC
  • Revision ID: brian.thomason@canonical.com-20111220172032-rdtm13jgdxtksacr
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src/org/bouncycastle/asn1/x9/X9ECParameters.java
 
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package org.bouncycastle.asn1.x9;
 
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import org.bouncycastle.asn1.ASN1Encodable;
 
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import org.bouncycastle.asn1.ASN1EncodableVector;
 
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import org.bouncycastle.asn1.ASN1OctetString;
 
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import org.bouncycastle.asn1.ASN1Sequence;
 
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import org.bouncycastle.asn1.DERInteger;
 
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import org.bouncycastle.asn1.DERObject;
 
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import org.bouncycastle.asn1.DERSequence;
 
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import org.bouncycastle.math.ec.ECCurve;
 
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import org.bouncycastle.math.ec.ECPoint;
 
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import java.math.BigInteger;
 
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/**
 
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 * ASN.1 def for Elliptic-Curve ECParameters structure. See
 
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 * X9.62, for further details.
 
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 */
 
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public class X9ECParameters
 
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    extends ASN1Encodable
 
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    implements X9ObjectIdentifiers
 
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{
 
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    private static final BigInteger   ONE = BigInteger.valueOf(1);
 
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    private X9FieldID           fieldID;
 
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    private ECCurve             curve;
 
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    private ECPoint             g;
 
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    private BigInteger          n;
 
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    private BigInteger          h;
 
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    private byte[]              seed;
 
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    public X9ECParameters(
 
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        ASN1Sequence  seq)
 
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    {
 
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        if (!(seq.getObjectAt(0) instanceof DERInteger)
 
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           || !((DERInteger)seq.getObjectAt(0)).getValue().equals(ONE))
 
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        {
 
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            throw new IllegalArgumentException("bad version in X9ECParameters");
 
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        }
 
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        X9Curve     x9c = new X9Curve(
 
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                        new X9FieldID((ASN1Sequence)seq.getObjectAt(1)),
 
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                        (ASN1Sequence)seq.getObjectAt(2));
 
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        this.curve = x9c.getCurve();
 
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        this.g = new X9ECPoint(curve, (ASN1OctetString)seq.getObjectAt(3)).getPoint();
 
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        this.n = ((DERInteger)seq.getObjectAt(4)).getValue();
 
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        this.seed = x9c.getSeed();
 
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        if (seq.size() == 6)
 
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        {
 
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            this.h = ((DERInteger)seq.getObjectAt(5)).getValue();
 
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        }
 
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    }
 
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    public X9ECParameters(
 
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        ECCurve     curve,
 
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        ECPoint     g,
 
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        BigInteger  n)
 
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    {
 
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        this(curve, g, n, ONE, null);
 
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    }
 
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    public X9ECParameters(
 
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        ECCurve     curve,
 
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        ECPoint     g,
 
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        BigInteger  n,
 
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        BigInteger  h)
 
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    {
 
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        this(curve, g, n, h, null);
 
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    }
 
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    public X9ECParameters(
 
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        ECCurve     curve,
 
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        ECPoint     g,
 
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        BigInteger  n,
 
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        BigInteger  h,
 
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        byte[]      seed)
 
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    {
 
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        this.curve = curve;
 
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        this.g = g;
 
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        this.n = n;
 
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        this.h = h;
 
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        this.seed = seed;
 
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        if (curve instanceof ECCurve.Fp)
 
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        {
 
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            this.fieldID = new X9FieldID(((ECCurve.Fp)curve).getQ());
 
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        }
 
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        else
 
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        {
 
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            if (curve instanceof ECCurve.F2m)
 
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            {
 
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                ECCurve.F2m curveF2m = (ECCurve.F2m)curve;
 
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                this.fieldID = new X9FieldID(curveF2m.getM(), curveF2m.getK1(),
 
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                    curveF2m.getK2(), curveF2m.getK3());
 
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            }
 
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        }
 
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    }
 
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    public ECCurve getCurve()
 
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    {
 
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        return curve;
 
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    }
 
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    public ECPoint getG()
 
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    {
 
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        return g;
 
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    }
 
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    public BigInteger getN()
 
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    {
 
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        return n;
 
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    }
 
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    public BigInteger getH()
 
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    {
 
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        if (h == null)
 
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        {
 
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            return ONE;        // TODO - this should be calculated, it will cause issues with custom curves.
 
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        }
 
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        return h;
 
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    }
 
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    public byte[] getSeed()
 
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    {
 
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        return seed;
 
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    }
 
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    /**
 
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     * Produce an object suitable for an ASN1OutputStream.
 
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     * <pre>
 
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     *  ECParameters ::= SEQUENCE {
 
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     *      version         INTEGER { ecpVer1(1) } (ecpVer1),
 
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     *      fieldID         FieldID {{FieldTypes}},
 
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     *      curve           X9Curve,
 
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     *      base            X9ECPoint,
 
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     *      order           INTEGER,
 
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     *      cofactor        INTEGER OPTIONAL
 
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     *  }
 
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     * </pre>
 
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     */
 
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    public DERObject toASN1Object()
 
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    {
 
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        ASN1EncodableVector v = new ASN1EncodableVector();
 
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        v.add(new DERInteger(1));
 
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        v.add(fieldID);
 
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        v.add(new X9Curve(curve, seed));
 
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        v.add(new X9ECPoint(g));
 
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        v.add(new DERInteger(n));
 
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        if (h != null)
 
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        {
 
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            v.add(new DERInteger(h));
 
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        }
 
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        return new DERSequence(v);
 
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    }
 
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}