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org.bouncycastle.math.ec.custom.sec.SecP224R1FieldElement Maven / Gradle / Ivy
package org.bouncycastle.math.ec.custom.sec;
import java.math.BigInteger;
import org.bouncycastle.math.ec.ECFieldElement;
import org.bouncycastle.math.raw.Mod;
import org.bouncycastle.math.raw.Nat;
import org.bouncycastle.math.raw.Nat224;
import org.bouncycastle.util.Arrays;
import org.bouncycastle.util.encoders.Hex;
public class SecP224R1FieldElement extends ECFieldElement.AbstractFp
{
public static final BigInteger Q = new BigInteger(1,
Hex.decodeStrict("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF000000000000000000000001"));
protected int[] x;
public SecP224R1FieldElement(BigInteger x)
{
if (x == null || x.signum() < 0 || x.compareTo(Q) >= 0)
{
throw new IllegalArgumentException("x value invalid for SecP224R1FieldElement");
}
this.x = SecP224R1Field.fromBigInteger(x);
}
public SecP224R1FieldElement()
{
this.x = Nat224.create();
}
protected SecP224R1FieldElement(int[] x)
{
this.x = x;
}
public boolean isZero()
{
return Nat224.isZero(x);
}
public boolean isOne()
{
return Nat224.isOne(x);
}
public boolean testBitZero()
{
return Nat224.getBit(x, 0) == 1;
}
public BigInteger toBigInteger()
{
return Nat224.toBigInteger(x);
}
public String getFieldName()
{
return "SecP224R1Field";
}
public int getFieldSize()
{
return Q.bitLength();
}
public ECFieldElement add(ECFieldElement b)
{
int[] z = Nat224.create();
SecP224R1Field.add(x, ((SecP224R1FieldElement)b).x, z);
return new SecP224R1FieldElement(z);
}
public ECFieldElement addOne()
{
int[] z = Nat224.create();
SecP224R1Field.addOne(x, z);
return new SecP224R1FieldElement(z);
}
public ECFieldElement subtract(ECFieldElement b)
{
int[] z = Nat224.create();
SecP224R1Field.subtract(x, ((SecP224R1FieldElement)b).x, z);
return new SecP224R1FieldElement(z);
}
public ECFieldElement multiply(ECFieldElement b)
{
int[] z = Nat224.create();
SecP224R1Field.multiply(x, ((SecP224R1FieldElement)b).x, z);
return new SecP224R1FieldElement(z);
}
public ECFieldElement divide(ECFieldElement b)
{
// return multiply(b.invert());
int[] z = Nat224.create();
SecP224R1Field.inv(((SecP224R1FieldElement)b).x, z);
SecP224R1Field.multiply(z, x, z);
return new SecP224R1FieldElement(z);
}
public ECFieldElement negate()
{
int[] z = Nat224.create();
SecP224R1Field.negate(x, z);
return new SecP224R1FieldElement(z);
}
public ECFieldElement square()
{
int[] z = Nat224.create();
SecP224R1Field.square(x, z);
return new SecP224R1FieldElement(z);
}
public ECFieldElement invert()
{
// return new SecP224R1FieldElement(toBigInteger().modInverse(Q));
int[] z = Nat224.create();
SecP224R1Field.inv(x, z);
return new SecP224R1FieldElement(z);
}
/**
* return a sqrt root - the routine verifies that the calculation returns the right value - if
* none exists it returns null.
*/
public ECFieldElement sqrt()
{
int[] c = this.x;
if (Nat224.isZero(c) || Nat224.isOne(c))
{
return this;
}
int[] nc = Nat224.create();
SecP224R1Field.negate(c, nc);
int[] r = Mod.random(SecP224R1Field.P);
int[] t = Nat224.create();
if (!isSquare(c))
{
return null;
}
while (!trySqrt(nc, r, t))
{
SecP224R1Field.addOne(r, r);
}
SecP224R1Field.square(t, r);
return Nat224.eq(c, r) ? new SecP224R1FieldElement(t) : null;
}
public boolean equals(Object other)
{
if (other == this)
{
return true;
}
if (!(other instanceof SecP224R1FieldElement))
{
return false;
}
SecP224R1FieldElement o = (SecP224R1FieldElement)other;
return Nat224.eq(x, o.x);
}
public int hashCode()
{
return Q.hashCode() ^ Arrays.hashCode(x, 0, 7);
}
private static boolean isSquare(int[] x)
{
int[] t1 = Nat224.create();
int[] t2 = Nat224.create();
Nat224.copy(x, t1);
for (int i = 0; i < 7; ++i)
{
Nat224.copy(t1, t2);
SecP224R1Field.squareN(t1, 1 << i, t1);
SecP224R1Field.multiply(t1, t2, t1);
}
SecP224R1Field.squareN(t1, 95, t1);
return Nat224.isOne(t1);
}
private static void RM(int[] nc, int[] d0, int[] e0, int[] d1, int[] e1, int[] f1, int[] t)
{
SecP224R1Field.multiply(e1, e0, t);
SecP224R1Field.multiply(t, nc, t);
SecP224R1Field.multiply(d1, d0, f1);
SecP224R1Field.add(f1, t, f1);
SecP224R1Field.multiply(d1, e0, t);
Nat224.copy(f1, d1);
SecP224R1Field.multiply(e1, d0, e1);
SecP224R1Field.add(e1, t, e1);
SecP224R1Field.square(e1, f1);
SecP224R1Field.multiply(f1, nc, f1);
}
private static void RP(int[] nc, int[] d1, int[] e1, int[] f1, int[] t)
{
Nat224.copy(nc, f1);
int[] d0 = Nat224.create();
int[] e0 = Nat224.create();
for (int i = 0; i < 7; ++i)
{
Nat224.copy(d1, d0);
Nat224.copy(e1, e0);
int j = 1 << i;
while (--j >= 0)
{
RS(d1, e1, f1, t);
}
RM(nc, d0, e0, d1, e1, f1, t);
}
}
private static void RS(int[] d, int[] e, int[] f, int[] t)
{
SecP224R1Field.multiply(e, d, e);
SecP224R1Field.twice(e, e);
SecP224R1Field.square(d, t);
SecP224R1Field.add(f, t, d);
SecP224R1Field.multiply(f, t, f);
int c = Nat.shiftUpBits(7, f, 2, 0);
SecP224R1Field.reduce32(c, f);
}
private static boolean trySqrt(int[] nc, int[] r, int[] t)
{
int[] d1 = Nat224.create();
Nat224.copy(r, d1);
int[] e1 = Nat224.create();
e1[0] = 1;
int[] f1 = Nat224.create();
RP(nc, d1, e1, f1, t);
int[] d0 = Nat224.create();
int[] e0 = Nat224.create();
for (int k = 1; k < 96; ++k)
{
Nat224.copy(d1, d0);
Nat224.copy(e1, e0);
RS(d1, e1, f1, t);
if (Nat224.isZero(d1))
{
SecP224R1Field.inv(e0, t);
SecP224R1Field.multiply(t, d0, t);
return true;
}
}
return false;
}
}
