org.cryptoworkshop.ximix.common.asn1.board.PointSequence.java Source code

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Here is the source code for org.cryptoworkshop.ximix.common.asn1.board.PointSequence.java

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/**
 * Copyright 2013 Crypto Workshop Pty Ltd
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.cryptoworkshop.ximix.common.asn1.board;

import org.bouncycastle.asn1.ASN1EncodableVector;
import org.bouncycastle.asn1.ASN1Object;
import org.bouncycastle.asn1.ASN1OctetString;
import org.bouncycastle.asn1.ASN1Primitive;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.DEROctetString;
import org.bouncycastle.asn1.DERSequence;
import org.bouncycastle.math.ec.ECCurve;
import org.bouncycastle.math.ec.ECPoint;

/**
 * Helper class for carrying an array of EC points.
 */
public class PointSequence extends ASN1Object {
    private final ECPoint[] ecPoints;

    /**
     * Create a sequence from a single point.
     *
     * @param ecPoint the point to include.
     */
    public PointSequence(ECPoint ecPoint) {
        this.ecPoints = new ECPoint[] { ecPoint };
    }

    /**
     * Create a sequence from a collection of points.
     *
     * @param ecPoints the points to include.
     */
    public PointSequence(ECPoint... ecPoints) {
        this.ecPoints = ecPoints.clone();
    }

    private PointSequence(ECCurve curve, ASN1Sequence s) {
        ecPoints = new ECPoint[s.size()];

        for (int i = 0; i != ecPoints.length; i++) {
            ecPoints[i] = curve.decodePoint(ASN1OctetString.getInstance(s.getObjectAt(i)).getOctets());
        }
    }

    /**
     * <pre>
     *     PointSequence ::= SEQUENCE OF Point
     * </pre>
     *
     * @return an encoding of an ASN.1 sequence
     */
    public ASN1Primitive toASN1Primitive() {
        ASN1EncodableVector v = new ASN1EncodableVector();

        for (ECPoint point : ecPoints) {
            v.add(new DEROctetString(point.getEncoded()));
        }

        return new DERSequence(v);
    }

    /**
     * Reconstruct a PointSequence from it's ASN.1 representation.
     *
     * @param curve the curve that the points in the sequence belong to.
     * @param o the sequence object.
     * @return a constructed EC pair sequence.
     */
    public static PointSequence getInstance(ECCurve curve, Object o) {
        if (o instanceof PointSequence) {
            return (PointSequence) o;
        }
        if (o != null) {
            return new PointSequence(curve, ASN1Sequence.getInstance(o));
        }

        return null;
    }

    /**
     * Return the EC points held in this sequence.
     *
     * @return an array of EC points..
     */
    public ECPoint[] getECPoints() {
        return ecPoints;
    }

    /**
     * Return the number of points contained in the sequence.
     *
     * @return the size of the sequence.
     */
    public int size() {
        return ecPoints.length;
    }
}