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using System;
using Org.BouncyCastle.Math.Raw;
using Org.BouncyCastle.Utilities;
namespace Org.BouncyCastle.Math.EC.Custom.Sec
{
internal class SecP160R2FieldElement
: AbstractFpFieldElement
{
public static readonly BigInteger Q = SecP160R2Curve.q;
protected internal readonly uint[] x;
public SecP160R2FieldElement(BigInteger x)
{
if (x == null || x.SignValue < 0 || x.CompareTo(Q) >= 0)
throw new ArgumentException("value invalid for SecP160R2FieldElement", "x");
this.x = SecP160R2Field.FromBigInteger(x);
}
public SecP160R2FieldElement()
{
this.x = Nat160.Create();
}
protected internal SecP160R2FieldElement(uint[] x)
{
this.x = x;
}
public override bool IsZero
{
get { return Nat160.IsZero(x); }
}
public override bool IsOne
{
get { return Nat160.IsOne(x); }
}
public override bool TestBitZero()
{
return Nat160.GetBit(x, 0) == 1;
}
public override BigInteger ToBigInteger()
{
return Nat160.ToBigInteger(x);
}
public override string FieldName
{
get { return "SecP160R2Field"; }
}
public override int FieldSize
{
get { return Q.BitLength; }
}
public override ECFieldElement Add(ECFieldElement b)
{
uint[] z = Nat160.Create();
SecP160R2Field.Add(x, ((SecP160R2FieldElement)b).x, z);
return new SecP160R2FieldElement(z);
}
public override ECFieldElement AddOne()
{
uint[] z = Nat160.Create();
SecP160R2Field.AddOne(x, z);
return new SecP160R2FieldElement(z);
}
public override ECFieldElement Subtract(ECFieldElement b)
{
uint[] z = Nat160.Create();
SecP160R2Field.Subtract(x, ((SecP160R2FieldElement)b).x, z);
return new SecP160R2FieldElement(z);
}
public override ECFieldElement Multiply(ECFieldElement b)
{
uint[] z = Nat160.Create();
SecP160R2Field.Multiply(x, ((SecP160R2FieldElement)b).x, z);
return new SecP160R2FieldElement(z);
}
public override ECFieldElement Divide(ECFieldElement b)
{
// return Multiply(b.invert());
uint[] z = Nat160.Create();
Mod.Invert(SecP160R2Field.P, ((SecP160R2FieldElement)b).x, z);
SecP160R2Field.Multiply(z, x, z);
return new SecP160R2FieldElement(z);
}
public override ECFieldElement Negate()
{
uint[] z = Nat160.Create();
SecP160R2Field.Negate(x, z);
return new SecP160R2FieldElement(z);
}
public override ECFieldElement Square()
{
uint[] z = Nat160.Create();
SecP160R2Field.Square(x, z);
return new SecP160R2FieldElement(z);
}
public override ECFieldElement Invert()
{
// return new SecP160R2FieldElement(ToBigInteger().modInverse(Q));
uint[] z = Nat160.Create();
Mod.Invert(SecP160R2Field.P, 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 override 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]
*/
uint[] x1 = this.x;
if (Nat160.IsZero(x1) || Nat160.IsOne(x1))
{
return this;
}
uint[] x2 = Nat160.Create();
SecP160R2Field.Square(x1, x2);
SecP160R2Field.Multiply(x2, x1, x2);
uint[] x3 = Nat160.Create();
SecP160R2Field.Square(x2, x3);
SecP160R2Field.Multiply(x3, x1, x3);
uint[] x4 = Nat160.Create();
SecP160R2Field.Square(x3, x4);
SecP160R2Field.Multiply(x4, x1, x4);
uint[] x7 = Nat160.Create();
SecP160R2Field.SquareN(x4, 3, x7);
SecP160R2Field.Multiply(x7, x3, x7);
uint[] x14 = x4;
SecP160R2Field.SquareN(x7, 7, x14);
SecP160R2Field.Multiply(x14, x7, x14);
uint[] x17 = x7;
SecP160R2Field.SquareN(x14, 3, x17);
SecP160R2Field.Multiply(x17, x3, x17);
uint[] x31 = Nat160.Create();
SecP160R2Field.SquareN(x17, 14, x31);
SecP160R2Field.Multiply(x31, x14, x31);
uint[] x62 = x14;
SecP160R2Field.SquareN(x31, 31, x62);
SecP160R2Field.Multiply(x62, x31, x62);
uint[] x124 = x31;
SecP160R2Field.SquareN(x62, 62, x124);
SecP160R2Field.Multiply(x124, x62, x124);
uint[] x127 = x62;
SecP160R2Field.SquareN(x124, 3, x127);
SecP160R2Field.Multiply(x127, x3, x127);
uint[] 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);
uint[] t2 = x2;
SecP160R2Field.Square(t1, t2);
return Nat160.Eq(x1, t2) ? new SecP160R2FieldElement(t1) : null;
}
public override bool Equals(object obj)
{
return Equals(obj as SecP160R2FieldElement);
}
public override bool Equals(ECFieldElement other)
{
return Equals(other as SecP160R2FieldElement);
}
public virtual bool Equals(SecP160R2FieldElement other)
{
if (this == other)
return true;
if (null == other)
return false;
return Nat160.Eq(x, other.x);
}
public override int GetHashCode()
{
return Q.GetHashCode() ^ Arrays.GetHashCode(x, 0, 5);
}
}
}
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