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The Bouncy Castle Java APIs for CMS, PKCS, EAC, TSP, CMP, CRMF, OCSP, and certificate generation. This jar contains APIs for JDK 1.5 and up. The APIs can be used in conjunction with a JCE/JCA provider such as the one provided with the Bouncy Castle Cryptography APIs.

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package org.bouncycastle.math.ec.custom.sec;

import java.math.BigInteger;

import org.bouncycastle.math.ec.ECFieldElement;
import org.bouncycastle.math.raw.Nat192;
import org.bouncycastle.util.Arrays;
import org.bouncycastle.util.encoders.Hex;

public class SecP192R1FieldElement extends ECFieldElement.AbstractFp
{
    public static final BigInteger Q = new BigInteger(1,
        Hex.decodeStrict("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFFFFFFFFFFFFF"));

    protected int[] x;

    public SecP192R1FieldElement(BigInteger x)
    {
        if (x == null || x.signum() < 0 || x.compareTo(Q) >= 0)
        {
            throw new IllegalArgumentException("x value invalid for SecP192R1FieldElement");
        }

        this.x = SecP192R1Field.fromBigInteger(x);
    }

    public SecP192R1FieldElement()
    {
        this.x = Nat192.create();
    }

    protected SecP192R1FieldElement(int[] x)
    {
        this.x = x;
    }

    public boolean isZero()
    {
        return Nat192.isZero(x);
    }

    public boolean isOne()
    {
        return Nat192.isOne(x);
    }

    public boolean testBitZero()
    {
        return Nat192.getBit(x, 0) == 1;
    }

    public BigInteger toBigInteger()
    {
        return Nat192.toBigInteger(x);
    }

    public String getFieldName()
    {
        return "SecP192R1Field";
    }

    public int getFieldSize()
    {
        return Q.bitLength();
    }

    public ECFieldElement add(ECFieldElement b)
    {
        int[] z = Nat192.create();
        SecP192R1Field.add(x, ((SecP192R1FieldElement)b).x, z);
        return new SecP192R1FieldElement(z);
    }

    public ECFieldElement addOne()
    {
        int[] z = Nat192.create();
        SecP192R1Field.addOne(x, z);
        return new SecP192R1FieldElement(z);
    }

    public ECFieldElement subtract(ECFieldElement b)
    {
        int[] z = Nat192.create();
        SecP192R1Field.subtract(x, ((SecP192R1FieldElement)b).x, z);
        return new SecP192R1FieldElement(z);
    }

    public ECFieldElement multiply(ECFieldElement b)
    {
        int[] z = Nat192.create();
        SecP192R1Field.multiply(x, ((SecP192R1FieldElement)b).x, z);
        return new SecP192R1FieldElement(z);
    }

    public ECFieldElement divide(ECFieldElement b)
    {
//        return multiply(b.invert());
        int[] z = Nat192.create();
        SecP192R1Field.inv(((SecP192R1FieldElement)b).x, z);
        SecP192R1Field.multiply(z, x, z);
        return new SecP192R1FieldElement(z);
    }

    public ECFieldElement negate()
    {
        int[] z = Nat192.create();
        SecP192R1Field.negate(x, z);
        return new SecP192R1FieldElement(z);
    }

    public ECFieldElement square()
    {
        int[] z = Nat192.create();
        SecP192R1Field.square(x, z);
        return new SecP192R1FieldElement(z);
    }

    public ECFieldElement invert()
    {
//        return new SecP192R1FieldElement(toBigInteger().modInverse(Q));
        int[] z = Nat192.create();
        SecP192R1Field.inv(x, z);
        return new SecP192R1FieldElement(z);
    }

    // D.1.4 91
    /**
     * return a sqrt root - the routine verifies that the calculation returns the right value - if
     * none exists it returns null.
     */
    public ECFieldElement sqrt()
    {
        // Raise this element to the exponent 2^190 - 2^62

        int[] x1 = this.x;
        if (Nat192.isZero(x1) || Nat192.isOne(x1))
        {
            return this;
        }

        int[] t1 = Nat192.create();
        int[] t2 = Nat192.create();

        SecP192R1Field.square(x1, t1);
        SecP192R1Field.multiply(t1, x1, t1);

        SecP192R1Field.squareN(t1, 2, t2);
        SecP192R1Field.multiply(t2, t1, t2);

        SecP192R1Field.squareN(t2, 4, t1);
        SecP192R1Field.multiply(t1, t2, t1);

        SecP192R1Field.squareN(t1, 8, t2);
        SecP192R1Field.multiply(t2, t1, t2);

        SecP192R1Field.squareN(t2, 16, t1);
        SecP192R1Field.multiply(t1, t2, t1);

        SecP192R1Field.squareN(t1, 32, t2);
        SecP192R1Field.multiply(t2, t1, t2);

        SecP192R1Field.squareN(t2, 64, t1);
        SecP192R1Field.multiply(t1, t2, t1);

        SecP192R1Field.squareN(t1, 62, t1);
        SecP192R1Field.square(t1, t2);

        return Nat192.eq(x1, t2) ? new SecP192R1FieldElement(t1) : null;
    }

    public boolean equals(Object other)
    {
        if (other == this)
        {
            return true;
        }

        if (!(other instanceof SecP192R1FieldElement))
        {
            return false;
        }

        SecP192R1FieldElement o = (SecP192R1FieldElement)other;
        return Nat192.eq(x, o.x);
    }

    public int hashCode()
    {
        return Q.hashCode() ^ Arrays.hashCode(x, 0, 6);
    }
}