EdwardsCurveBase.cs

using System;
using System.Security.Cryptography;
using System.Numerics;
 
namespace Waher.Security.EllipticCurves
{
    public abstract class EdwardsCurveBase : PrimeFieldCurve
    {
        protected BigInteger d;
 
        protected BigInteger d2;
 
        public EdwardsCurveBase(BigInteger Prime, PointOnCurve BasePoint,
            BigInteger d, BigInteger Order, int Cofactor)
            : this(Prime, BasePoint, d, Order, Cofactor, null)
        {
        }
 
        public EdwardsCurveBase(BigInteger Prime, PointOnCurve BasePoint, BigInteger d,
            BigInteger Order, int Cofactor, byte[] Secret)
            : base(Prime, BasePoint, Order, Cofactor, Secret)
        {
            this.d = d;
            this.d2 = BigInteger.Remainder(d << 1, this.p);
        }
 
        public abstract int CoordinateBits
        {
            get;
        }
 
        public override PointOnCurve Zero
        {
            get
            {
                return new PointOnCurve(BigInteger.Zero, BigInteger.One);
            }
        }
 
        public abstract BigInteger GetX(BigInteger Y, bool X0);
 
        public override byte[] Encode(PointOnCurve Point)
        {
            return EdDSA.Encode(Point, this);
        }
 
        public override PointOnCurve Decode(byte[] Point)
        {
            return EdDSA.Decode(Point, this);
        }
 
        public void Negate(ref PointOnCurve P)
        {
            P.X = this.p - P.X;
        }
    }
}