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using System;
using Org.BouncyCastle.Math.Raw;
using Org.BouncyCastle.Utilities;
using Org.BouncyCastle.Utilities.Encoders;
namespace Org.BouncyCastle.Math.EC.Custom.Sec
{
internal class SecP256R1FieldElement
: AbstractFpFieldElement
{
public static readonly BigInteger Q = new BigInteger(1,
Hex.DecodeStrict("FFFFFFFF00000001000000000000000000000000FFFFFFFFFFFFFFFFFFFFFFFF"));
protected internal readonly uint[] x;
public SecP256R1FieldElement(BigInteger x)
{
if (x == null || x.SignValue < 0 || x.CompareTo(Q) >= 0)
throw new ArgumentException("value invalid for SecP256R1FieldElement", "x");
this.x = SecP256R1Field.FromBigInteger(x);
}
public SecP256R1FieldElement()
{
this.x = Nat256.Create();
}
protected internal SecP256R1FieldElement(uint[] x)
{
this.x = x;
}
public override bool IsZero
{
get { return Nat256.IsZero(x); }
}
public override bool IsOne
{
get { return Nat256.IsOne(x); }
}
public override bool TestBitZero()
{
return Nat256.GetBit(x, 0) == 1;
}
public override BigInteger ToBigInteger()
{
return Nat256.ToBigInteger(x);
}
public override string FieldName
{
get { return "SecP256R1Field"; }
}
public override int FieldSize
{
get { return Q.BitLength; }
}
public override ECFieldElement Add(ECFieldElement b)
{
uint[] z = Nat256.Create();
SecP256R1Field.Add(x, ((SecP256R1FieldElement)b).x, z);
return new SecP256R1FieldElement(z);
}
public override ECFieldElement AddOne()
{
uint[] z = Nat256.Create();
SecP256R1Field.AddOne(x, z);
return new SecP256R1FieldElement(z);
}
public override ECFieldElement Subtract(ECFieldElement b)
{
uint[] z = Nat256.Create();
SecP256R1Field.Subtract(x, ((SecP256R1FieldElement)b).x, z);
return new SecP256R1FieldElement(z);
}
public override ECFieldElement Multiply(ECFieldElement b)
{
uint[] z = Nat256.Create();
SecP256R1Field.Multiply(x, ((SecP256R1FieldElement)b).x, z);
return new SecP256R1FieldElement(z);
}
public override ECFieldElement Divide(ECFieldElement b)
{
//return Multiply(b.Invert());
uint[] z = Nat256.Create();
SecP256R1Field.Inv(((SecP256R1FieldElement)b).x, z);
SecP256R1Field.Multiply(z, x, z);
return new SecP256R1FieldElement(z);
}
public override ECFieldElement Negate()
{
uint[] z = Nat256.Create();
SecP256R1Field.Negate(x, z);
return new SecP256R1FieldElement(z);
}
public override ECFieldElement Square()
{
uint[] z = Nat256.Create();
SecP256R1Field.Square(x, z);
return new SecP256R1FieldElement(z);
}
public override ECFieldElement Invert()
{
//return new SecP256R1FieldElement(ToBigInteger().ModInverse(Q));
uint[] z = Nat256.Create();
SecP256R1Field.Inv(x, z);
return new SecP256R1FieldElement(z);
}
/**
* 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 2^254 - 2^222 + 2^190 + 2^94
uint[] x1 = this.x;
if (Nat256.IsZero(x1) || Nat256.IsOne(x1))
return this;
uint[] tt0 = Nat256.CreateExt();
uint[] t1 = Nat256.Create();
uint[] t2 = Nat256.Create();
SecP256R1Field.Square(x1, t1, tt0);
SecP256R1Field.Multiply(t1, x1, t1, tt0);
SecP256R1Field.SquareN(t1, 2, t2, tt0);
SecP256R1Field.Multiply(t2, t1, t2, tt0);
SecP256R1Field.SquareN(t2, 4, t1, tt0);
SecP256R1Field.Multiply(t1, t2, t1, tt0);
SecP256R1Field.SquareN(t1, 8, t2, tt0);
SecP256R1Field.Multiply(t2, t1, t2, tt0);
SecP256R1Field.SquareN(t2, 16, t1, tt0);
SecP256R1Field.Multiply(t1, t2, t1, tt0);
SecP256R1Field.SquareN(t1, 32, t1, tt0);
SecP256R1Field.Multiply(t1, x1, t1, tt0);
SecP256R1Field.SquareN(t1, 96, t1, tt0);
SecP256R1Field.Multiply(t1, x1, t1, tt0);
SecP256R1Field.SquareN(t1, 94, t1, tt0);
SecP256R1Field.Multiply(t1, t1, t2, tt0);
return Nat256.Eq(x1, t2) ? new SecP256R1FieldElement(t1) : null;
}
public override bool Equals(object obj)
{
return Equals(obj as SecP256R1FieldElement);
}
public override bool Equals(ECFieldElement other)
{
return Equals(other as SecP256R1FieldElement);
}
public virtual bool Equals(SecP256R1FieldElement other)
{
if (this == other)
return true;
if (null == other)
return false;
return Nat256.Eq(x, other.x);
}
public override int GetHashCode()
{
return Q.GetHashCode() ^ Arrays.GetHashCode(x, 0, 8);
}
}
}
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