/// <summary>
/// Abstract base class for elliptic curves.
/// </summary>
/// <param name="BasePoint">Base-point.</param>
/// <param name="Order">Order of base-point.</param>
/// <param name="Cofactor">Cofactor of curve.</param>
/// <param name="Secret">Secret.</param>
public EllipticCurve(PointOnCurve BasePoint, BigInteger Order, int Cofactor,
byte[] Secret)
{
this.g = BasePoint;
this.n = Order;
this.cofactor = Cofactor;
this.secret = Secret;
this.privateKey = null;
this.publicKey = null;
this.additionalInfo = null;
this.orderBits = ModulusP.CalcBits(this.n);
this.orderBytes = (this.orderBits + 7) >> 3;
this.msbOrderMask = 0xff;
int MaskBits = (8 - this.orderBits) & 7;
if (MaskBits == 0)
{
this.orderBytes++;
this.msbOrderMask = 0;
}
else
{
this.msbOrderMask >>= MaskBits;
}
}
/// <summary>
/// Base class of Elliptic curves over a prime field.
/// </summary>
/// <param name="Prime">Prime base of field.</param>
/// <param name="BasePoint">Base-point.</param>
/// <param name="A">a Coefficient in the definition of the curve E: y^2=x^3+a*x+b</param>
/// <param name="Order">Order of base-point.</param>
/// <param name="OrderBits">Number of bits used to encode order.</param>
public CurvePrimeField(BigInteger Prime, PointOnCurve BasePoint, BigInteger A,
BigInteger Order, int OrderBits)
: base(Prime)
{
if (Prime <= BigInteger.One)
{
throw new ArgumentException("Invalid prime base.", nameof(Prime));
}
this.g = BasePoint;
this.a = A;
this.n = Order;
this.orderBits = OrderBits;
this.orderBytes = (OrderBits + 7) >> 3;
this.modN = new ModulusP(Order);
this.msbMask = 0xff;
int MaskBits = (8 - OrderBits) & 7;
if (MaskBits == 0)
{
this.orderBytes++;
this.msbMask = 0;
}
else
{
this.msbMask >>= MaskBits;
}
this.GenerateKeys();
}
/// <summary>
/// Base class of Elliptic curves over a prime field.
/// </summary>
/// <param name="Prime">Prime base of field.</param>
/// <param name="BasePoint">Base-point.</param>
/// <param name="Order">Order of base-point.</param>
/// <param name="Cofactor">Cofactor of curve.</param>
/// <param name="Secret">Secret.</param>
public PrimeFieldCurve(BigInteger Prime, PointOnCurve BasePoint, BigInteger Order,
int Cofactor, byte[] Secret)
: base(BasePoint, Order, Cofactor, Secret)
{
if (Prime <= BigInteger.One)
{
throw new ArgumentException("Invalid prime base.", nameof(Prime));
}
this.p = Prime;
this.modP = new ModulusP(Prime);
this.modN = new ModulusP(Order);
}