org.bouncycastle.math.ec.custom.sec.SecP160R2FieldElement Maven / Gradle / Ivy
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The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.4.
package org.bouncycastle.math.ec.custom.sec;
import java.math.BigInteger;
import org.bouncycastle.math.ec.ECFieldElement;
import org.bouncycastle.math.raw.Nat160;
import org.bouncycastle.util.Arrays;
import org.bouncycastle.util.encoders.Hex;
public class SecP160R2FieldElement extends ECFieldElement.AbstractFp
{
public static final BigInteger Q = new BigInteger(1,
Hex.decodeStrict("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFAC73"));
protected int[] x;
public SecP160R2FieldElement(BigInteger x)
{
if (x == null || x.signum() < 0 || x.compareTo(Q) >= 0)
{
throw new IllegalArgumentException("x value invalid for SecP160R2FieldElement");
}
this.x = SecP160R2Field.fromBigInteger(x);
}
public SecP160R2FieldElement()
{
this.x = Nat160.create();
}
protected SecP160R2FieldElement(int[] x)
{
this.x = x;
}
public boolean isZero()
{
return Nat160.isZero(x);
}
public boolean isOne()
{
return Nat160.isOne(x);
}
public boolean testBitZero()
{
return Nat160.getBit(x, 0) == 1;
}
public BigInteger toBigInteger()
{
return Nat160.toBigInteger(x);
}
public String getFieldName()
{
return "SecP160R2Field";
}
public int getFieldSize()
{
return Q.bitLength();
}
public ECFieldElement add(ECFieldElement b)
{
int[] z = Nat160.create();
SecP160R2Field.add(x, ((SecP160R2FieldElement)b).x, z);
return new SecP160R2FieldElement(z);
}
public ECFieldElement addOne()
{
int[] z = Nat160.create();
SecP160R2Field.addOne(x, z);
return new SecP160R2FieldElement(z);
}
public ECFieldElement subtract(ECFieldElement b)
{
int[] z = Nat160.create();
SecP160R2Field.subtract(x, ((SecP160R2FieldElement)b).x, z);
return new SecP160R2FieldElement(z);
}
public ECFieldElement multiply(ECFieldElement b)
{
int[] z = Nat160.create();
SecP160R2Field.multiply(x, ((SecP160R2FieldElement)b).x, z);
return new SecP160R2FieldElement(z);
}
public ECFieldElement divide(ECFieldElement b)
{
// return multiply(b.invert());
int[] z = Nat160.create();
SecP160R2Field.inv(((SecP160R2FieldElement)b).x, z);
SecP160R2Field.multiply(z, x, z);
return new SecP160R2FieldElement(z);
}
public ECFieldElement negate()
{
int[] z = Nat160.create();
SecP160R2Field.negate(x, z);
return new SecP160R2FieldElement(z);
}
public ECFieldElement square()
{
int[] z = Nat160.create();
SecP160R2Field.square(x, z);
return new SecP160R2FieldElement(z);
}
public ECFieldElement invert()
{
// return new SecP160R2FieldElement(toBigInteger().modInverse(Q));
int[] z = Nat160.create();
SecP160R2Field.inv(x, z);
return new SecP160R2FieldElement(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 2^158 - 2^30 - 2^12 - 2^10 - 2^7 - 2^6 - 2^5 - 2^1 - 2^0
*
* Breaking up the exponent's binary representation into "repunits", we get: { 127 1s } { 1
* 0s } { 17 1s } { 1 0s } { 1 1s } { 1 0s } { 2 1s } { 3 0s } { 3 1s } { 1 0s } { 1 1s }
*
* Therefore we need an addition chain containing 1, 2, 3, 17, 127 (the lengths of the repunits)
* We use: [1], [2], [3], 4, 7, 14, [17], 31, 62, 124, [127]
*/
int[] x1 = this.x;
if (Nat160.isZero(x1) || Nat160.isOne(x1))
{
return this;
}
int[] x2 = Nat160.create();
SecP160R2Field.square(x1, x2);
SecP160R2Field.multiply(x2, x1, x2);
int[] x3 = Nat160.create();
SecP160R2Field.square(x2, x3);
SecP160R2Field.multiply(x3, x1, x3);
int[] x4 = Nat160.create();
SecP160R2Field.square(x3, x4);
SecP160R2Field.multiply(x4, x1, x4);
int[] x7 = Nat160.create();
SecP160R2Field.squareN(x4, 3, x7);
SecP160R2Field.multiply(x7, x3, x7);
int[] x14 = x4;
SecP160R2Field.squareN(x7, 7, x14);
SecP160R2Field.multiply(x14, x7, x14);
int[] x17 = x7;
SecP160R2Field.squareN(x14, 3, x17);
SecP160R2Field.multiply(x17, x3, x17);
int[] x31 = Nat160.create();
SecP160R2Field.squareN(x17, 14, x31);
SecP160R2Field.multiply(x31, x14, x31);
int[] x62 = x14;
SecP160R2Field.squareN(x31, 31, x62);
SecP160R2Field.multiply(x62, x31, x62);
int[] x124 = x31;
SecP160R2Field.squareN(x62, 62, x124);
SecP160R2Field.multiply(x124, x62, x124);
int[] x127 = x62;
SecP160R2Field.squareN(x124, 3, x127);
SecP160R2Field.multiply(x127, x3, x127);
int[] t1 = x127;
SecP160R2Field.squareN(t1, 18, t1);
SecP160R2Field.multiply(t1, x17, t1);
SecP160R2Field.squareN(t1, 2, t1);
SecP160R2Field.multiply(t1, x1, t1);
SecP160R2Field.squareN(t1, 3, t1);
SecP160R2Field.multiply(t1, x2, t1);
SecP160R2Field.squareN(t1, 6, t1);
SecP160R2Field.multiply(t1, x3, t1);
SecP160R2Field.squareN(t1, 2, t1);
SecP160R2Field.multiply(t1, x1, t1);
int[] t2 = x2;
SecP160R2Field.square(t1, t2);
return Nat160.eq(x1, t2) ? new SecP160R2FieldElement(t1) : null;
}
public boolean equals(Object other)
{
if (other == this)
{
return true;
}
if (!(other instanceof SecP160R2FieldElement))
{
return false;
}
SecP160R2FieldElement o = (SecP160R2FieldElement)other;
return Nat160.eq(x, o.x);
}
public int hashCode()
{
return Q.hashCode() ^ Arrays.hashCode(x, 0, 5);
}
}