Example usage for org.bouncycastle.math.ec ECCurve getCofactor

Introduction

In this page you can find the example usage for org.bouncycastle.math.ec ECCurve getCofactor.

Prototype

public BigInteger getCofactor() 

Source Link

Usage

From source file:com.github.horrorho.inflatabledonkey.crypto.ec.ECPointsCompact.java

License:Open Source License

@Deprecated
public static boolean satisfiesCofactor(ECCurve curve, ECPoint point) {
    // Patched org.bouncycastle.math.ec.ECPoint#satisfiesCofactor protected code.
    BigInteger h = curve.getCofactor();
    return h == null || h.equals(ECConstants.ONE) || !ECAlgorithms.referenceMultiply(point, h).isInfinity();
}

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From source file:dorkbox.util.serialization.EccPrivateKeySerializer.java

License:Apache License

static void serializeCurve(Output output, ECCurve curve) throws KryoException {
    byte[] bytes;
    int length;/*from   ww w  . j  a v  a  2 s.c  om*/
    // save out if it's a NAMED curve, or a UN-NAMED curve. If it is named, we can do less work.
    String curveName = curve.getClass().getSimpleName();

    if (CustomNamedCurves.getByName(curveName) != null) {
        // we use the name instead of serializing the full curve
        output.writeInt(usesName, true);
        output.writeString(curveName);
        return;
    }

    else if (curveName.endsWith("Curve")) {
        String cleanedName = curveName.substring(0, curveName.indexOf("Curve"));

        if (!cleanedName.isEmpty()) {
            ASN1ObjectIdentifier oid = CustomNamedCurves.getOID(cleanedName);
            if (oid != null) {
                // we use the OID (instead of serializing the entire curve)
                output.writeInt(usesOid, true);
                curveName = oid.getId();
                output.writeString(curveName);
                return;
            }
        }
    }

    // we have to serialize the ENTIRE curve.
    // save out the curve info
    BigInteger a = curve.getA().toBigInteger();
    BigInteger b = curve.getB().toBigInteger();
    BigInteger order = curve.getOrder();
    BigInteger cofactor = curve.getCofactor();
    BigInteger q = curve.getField().getCharacteristic();

    /////////////
    bytes = a.toByteArray();
    length = bytes.length;
    output.writeInt(length, true);
    output.writeBytes(bytes, 0, length);

    /////////////
    bytes = b.toByteArray();
    length = bytes.length;
    output.writeInt(length, true);
    output.writeBytes(bytes, 0, length);

    /////////////
    bytes = order.toByteArray();
    length = bytes.length;
    output.writeInt(length, true);
    output.writeBytes(bytes, 0, length);

    /////////////
    bytes = cofactor.toByteArray();
    length = bytes.length;
    output.writeInt(length, true);
    output.writeBytes(bytes, 0, length);

    /////////////
    bytes = q.toByteArray();
    length = bytes.length;
    output.writeInt(length, true);
    output.writeBytes(bytes, 0, length);

    // coordinate system
    int coordinateSystem = curve.getCoordinateSystem();
    output.writeInt(coordinateSystem, true);
}

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