ln.crypto.ec/ln.crypto.ec/CurvePoint.cs

using System;
using System.Text;
using System.Numerics;

namespace Crypto.EC
{
	public class CurvePoint
	{
		public static readonly CurvePoint INFINITY = new CurvePoint();

		public CurvePoint(EllipticCurve curve,BigInteger x,BigInteger y){
			Curve = curve;
			X = x;
			Y = y;
		}

		private CurvePoint(){
			this.Curve = null;
			this.X = 0;
			this.Y = 0;
		}

		public string toHexString()
		{
			StringBuilder sb = new StringBuilder();
			sb.Append(X.ToString("X"));
			sb.Append(".");
			sb.Append(Y.ToString("X"));
			return sb.ToString();
		}

		public string toHex()
		{
			StringBuilder sb = new StringBuilder();
			sb.Append(X.ToString("X32"));
			sb.Append(Y.ToString("X32"));
			return sb.ToString();
		}

		public override string ToString()
		{
			if ((object)this == (object)INFINITY){
				return String.Format("[CurvePoint INFINITY]");
			}
			return String.Format("[CurvePoint X={0} Y={1}]",X.ToString("X"),Y.ToString("X"));
		}

		public EllipticCurve Curve { get; private set; }
		public BigInteger X { get; private set; }
		public BigInteger Y { get; private set; }

		public bool isOnCurve(){
			return this.Curve.isOnCurve(this);
		}

		public bool isInfinity(){
			return ((object)this == (object)INFINITY);
		}

		public CurvePoint Negated(){
			return new CurvePoint(Curve, X, Curve.Fp.AdditiveInverse(Y));
		}

		public static CurvePoint operator +(CurvePoint p1, CurvePoint p2)
		{
			if ((object)p1 == (object)INFINITY){
				return p2;
			}
			if ((object)p2 == (object)INFINITY){
				return p1;
			}

			return p1.Curve.Add(p1, p2);
		}

		public static CurvePoint operator -(CurvePoint p1, CurvePoint p2)
		{
			if ((object)p1 == (object)INFINITY){
				return p2;
			}
			if ((object)p2 == (object)INFINITY){
				return p1;
			}
			return p1.Curve.Add(p1, p2.Negated());
		}

		public static CurvePoint operator *(CurvePoint p1, BigInteger n)
		{
			if ((object)p1 == (object)INFINITY){
				return INFINITY;
			}

			if (p1.Y == BigInteger.Zero){
				return INFINITY;
			}

			if (n.IsZero){
				throw new NotImplementedException("CurvePoint * 0");
			}

			CurvePoint result = null;
			CurvePoint p = p1;

			int i;
			byte[] nBytes = n.ToByteArray();

			for (i = 0; i < nBytes.Length<<3; i++)
			{
				if ((nBytes[i >> 3] & (1 << (i & 0x07))) != 0)
					break;
				
				p += p;
			}

			result = p;

			for (i++; i < nBytes.Length<<3; i++)
			{
				p += p;
				if ((nBytes[i >> 3] & (1 << (i & 0x07))) != 0)
				{
					result = p + result;
				}
			}

			return result;
		}

		public static bool operator ==(CurvePoint p1, CurvePoint p2)
		{
			if ((p1 is null)||(p2 is null)){
				return false;
			}
			return (p1.X == p2.X) && (p1.Y == p2.Y);
		}
		public static bool operator !=(CurvePoint p1, CurvePoint p2)
		{
			if ((p1 is null)||(p2 is null)){
				return false;
			}
			return (p1.X != p2.X) || (p1.Y != p2.Y);
		}

		public override bool Equals(object obj) => (obj is CurvePoint cp2) && X.Equals(cp2.X) && Y.Equals(cp2.Y);
        public override int GetHashCode() => X.GetHashCode() ^ Y.GetHashCode();

		public byte[] ToByteArray()
		{
			int bytesPerValue = Curve.Fp.FieldModulo.GetByteCount();
			byte[] result = new byte[bytesPerValue*2];
			X.TryWriteBytes(new Span<byte>(result, 0, bytesPerValue), out int bytesWritten);
			Y.TryWriteBytes(new Span<byte>(result, bytesPerValue, bytesPerValue), out bytesWritten);
			return result;
		}
    


	}
}