using Org.BouncyCastle.Utilities; using System; namespace Org.BouncyCastle.Math.EC { public abstract class AbstractF2mFieldElement : ECFieldElement { public virtual bool HasFastTrace => false; public virtual ECFieldElement HalfTrace() { int fieldSize = FieldSize; if ((fieldSize & 1) == 0) throw new InvalidOperationException("Half-trace only defined for odd m"); int num = fieldSize + 1 >> 1; int num2 = 31 - Integers.NumberOfLeadingZeros(num); int num3 = 1; ECFieldElement eCFieldElement = this; while (num2 > 0) { eCFieldElement = eCFieldElement.SquarePow(num3 << 1).Add(eCFieldElement); num3 = num >> --num2; if ((num3 & 1) != 0) eCFieldElement = eCFieldElement.SquarePow(2).Add(this); } return eCFieldElement; } public virtual int Trace() { int fieldSize = FieldSize; int num = 31 - Integers.NumberOfLeadingZeros(fieldSize); int num2 = 1; ECFieldElement eCFieldElement = this; while (num > 0) { eCFieldElement = eCFieldElement.SquarePow(num2).Add(eCFieldElement); num2 = fieldSize >> --num; if ((num2 & 1) != 0) eCFieldElement = eCFieldElement.Square().Add(this); } if (eCFieldElement.IsZero) return 0; if (eCFieldElement.IsOne) return 1; throw new InvalidOperationException("Internal error in trace calculation"); } } }