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package org.spongycastle.math.ec.custom.sec;
import java.math.BigInteger;
import org.spongycastle.math.ec.ECFieldElement;
import org.spongycastle.math.raw.Mod;
import org.spongycastle.math.raw.Nat;
import org.spongycastle.util.Arrays;
public class SecP521R1FieldElement extends ECFieldElement
{
public static final BigInteger Q = SecP521R1Curve.q;
protected int[] x;
public SecP521R1FieldElement(BigInteger x)
{
if (x == null || x.signum() < 0 || x.compareTo(Q) >= 0)
{
throw new IllegalArgumentException("x value invalid for SecP521R1FieldElement");
}
this.x = SecP521R1Field.fromBigInteger(x);
}
public SecP521R1FieldElement()
{
this.x = Nat.create(17);
}
protected SecP521R1FieldElement(int[] x)
{
this.x = x;
}
public boolean isZero()
{
return Nat.isZero(17, x);
}
public boolean isOne()
{
return Nat.isOne(17, x);
}
public boolean testBitZero()
{
return Nat.getBit(x, 0) == 1;
}
public BigInteger toBigInteger()
{
return Nat.toBigInteger(17, x);
}
public String getFieldName()
{
return "SecP521R1Field";
}
public int getFieldSize()
{
return Q.bitLength();
}
public ECFieldElement add(ECFieldElement b)
{
int[] z = Nat.create(17);
SecP521R1Field.add(x, ((SecP521R1FieldElement)b).x, z);
return new SecP521R1FieldElement(z);
}
public ECFieldElement addOne()
{
int[] z = Nat.create(17);
SecP521R1Field.addOne(x, z);
return new SecP521R1FieldElement(z);
}
public ECFieldElement subtract(ECFieldElement b)
{
int[] z = Nat.create(17);
SecP521R1Field.subtract(x, ((SecP521R1FieldElement)b).x, z);
return new SecP521R1FieldElement(z);
}
public ECFieldElement multiply(ECFieldElement b)
{
int[] z = Nat.create(17);
SecP521R1Field.multiply(x, ((SecP521R1FieldElement)b).x, z);
return new SecP521R1FieldElement(z);
}
public ECFieldElement divide(ECFieldElement b)
{
// return multiply(b.invert());
int[] z = Nat.create(17);
Mod.invert(SecP521R1Field.P, ((SecP521R1FieldElement)b).x, z);
SecP521R1Field.multiply(z, x, z);
return new SecP521R1FieldElement(z);
}
public ECFieldElement negate()
{
int[] z = Nat.create(17);
SecP521R1Field.negate(x, z);
return new SecP521R1FieldElement(z);
}
public ECFieldElement square()
{
int[] z = Nat.create(17);
SecP521R1Field.square(x, z);
return new SecP521R1FieldElement(z);
}
public ECFieldElement invert()
{
// return new SecP521R1FieldElement(toBigInteger().modInverse(Q));
int[] z = Nat.create(17);
Mod.invert(SecP521R1Field.P, x, z);
return new SecP521R1FieldElement(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 2^519
int[] x1 = this.x;
if (Nat.isZero(17, x1) || Nat.isOne(17, x1))
{
return this;
}
int[] t1 = Nat.create(17);
int[] t2 = Nat.create(17);
SecP521R1Field.squareN(x1, 519, t1);
SecP521R1Field.square(t1, t2);
return Nat.eq(17, x1, t2) ? new SecP521R1FieldElement(t1) : null;
}
public boolean equals(Object other)
{
if (other == this)
{
return true;
}
if (!(other instanceof SecP521R1FieldElement))
{
return false;
}
SecP521R1FieldElement o = (SecP521R1FieldElement)other;
return Nat.eq(17, x, o.x);
}
public int hashCode()
{
return Q.hashCode() ^ Arrays.hashCode(x, 0, 17);
}
}
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