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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 1.5 and up.
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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 SecP192K1FieldElement extends ECFieldElement.AbstractFp
{
public static final BigInteger Q = new BigInteger(1,
Hex.decodeStrict("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFEE37"));
protected int[] x;
public SecP192K1FieldElement(BigInteger x)
{
if (x == null || x.signum() < 0 || x.compareTo(Q) >= 0)
{
throw new IllegalArgumentException("x value invalid for SecP192K1FieldElement");
}
this.x = SecP192K1Field.fromBigInteger(x);
}
public SecP192K1FieldElement()
{
this.x = Nat192.create();
}
protected SecP192K1FieldElement(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 "SecP192K1Field";
}
public int getFieldSize()
{
return Q.bitLength();
}
public ECFieldElement add(ECFieldElement b)
{
int[] z = Nat192.create();
SecP192K1Field.add(x, ((SecP192K1FieldElement)b).x, z);
return new SecP192K1FieldElement(z);
}
public ECFieldElement addOne()
{
int[] z = Nat192.create();
SecP192K1Field.addOne(x, z);
return new SecP192K1FieldElement(z);
}
public ECFieldElement subtract(ECFieldElement b)
{
int[] z = Nat192.create();
SecP192K1Field.subtract(x, ((SecP192K1FieldElement)b).x, z);
return new SecP192K1FieldElement(z);
}
public ECFieldElement multiply(ECFieldElement b)
{
int[] z = Nat192.create();
SecP192K1Field.multiply(x, ((SecP192K1FieldElement)b).x, z);
return new SecP192K1FieldElement(z);
}
public ECFieldElement divide(ECFieldElement b)
{
// return multiply(b.invert());
int[] z = Nat192.create();
SecP192K1Field.inv(((SecP192K1FieldElement)b).x, z);
SecP192K1Field.multiply(z, x, z);
return new SecP192K1FieldElement(z);
}
public ECFieldElement negate()
{
int[] z = Nat192.create();
SecP192K1Field.negate(x, z);
return new SecP192K1FieldElement(z);
}
public ECFieldElement square()
{
int[] z = Nat192.create();
SecP192K1Field.square(x, z);
return new SecP192K1FieldElement(z);
}
public ECFieldElement invert()
{
// return new SecP192K1FieldElement(toBigInteger().modInverse(Q));
int[] z = Nat192.create();
SecP192K1Field.inv(x, z);
return new SecP192K1FieldElement(z);
}
/**
* 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 - 2^30 - 2^10 - 2^6 - 2^5 - 2^4 - 2^1
*
* Breaking up the exponent's binary representation into "repunits", we get:
* { 159 1s } { 1 0s } { 19 1s } { 1 0s } { 3 1s } { 3 0s } { 3 1s } { 1 0s }
*
* Therefore we need an addition chain containing 3, 19, 159 (the lengths of the repunits)
* We use: 1, 2, [3], 6, 8, 16, [19], 35, 70, 140, [159]
*/
int[] x1 = this.x;
if (Nat192.isZero(x1) || Nat192.isOne(x1))
{
return this;
}
int[] x2 = Nat192.create();
SecP192K1Field.square(x1, x2);
SecP192K1Field.multiply(x2, x1, x2);
int[] x3 = Nat192.create();
SecP192K1Field.square(x2, x3);
SecP192K1Field.multiply(x3, x1, x3);
int[] x6 = Nat192.create();
SecP192K1Field.squareN(x3, 3, x6);
SecP192K1Field.multiply(x6, x3, x6);
int[] x8 = x6;
SecP192K1Field.squareN(x6, 2, x8);
SecP192K1Field.multiply(x8, x2, x8);
int[] x16 = x2;
SecP192K1Field.squareN(x8, 8, x16);
SecP192K1Field.multiply(x16, x8, x16);
int[] x19 = x8;
SecP192K1Field.squareN(x16, 3, x19);
SecP192K1Field.multiply(x19, x3, x19);
int[] x35 = Nat192.create();
SecP192K1Field.squareN(x19, 16, x35);
SecP192K1Field.multiply(x35, x16, x35);
int[] x70 = x16;
SecP192K1Field.squareN(x35, 35, x70);
SecP192K1Field.multiply(x70, x35, x70);
int[] x140 = x35;
SecP192K1Field.squareN(x70, 70, x140);
SecP192K1Field.multiply(x140, x70, x140);
int[] x159 = x70;
SecP192K1Field.squareN(x140, 19, x159);
SecP192K1Field.multiply(x159, x19, x159);
int[] t1 = x159;
SecP192K1Field.squareN(t1, 20, t1);
SecP192K1Field.multiply(t1, x19, t1);
SecP192K1Field.squareN(t1, 4, t1);
SecP192K1Field.multiply(t1, x3, t1);
SecP192K1Field.squareN(t1, 6, t1);
SecP192K1Field.multiply(t1, x3, t1);
SecP192K1Field.square(t1, t1);
int[] t2 = x3;
SecP192K1Field.square(t1, t2);
return Nat192.eq(x1, t2) ? new SecP192K1FieldElement(t1) : null;
}
public boolean equals(Object other)
{
if (other == this)
{
return true;
}
if (!(other instanceof SecP192K1FieldElement))
{
return false;
}
SecP192K1FieldElement o = (SecP192K1FieldElement)other;
return Nat192.eq(x, o.x);
}
public int hashCode()
{
return Q.hashCode() ^ Arrays.hashCode(x, 0, 6);
}
}
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