init commit

output/Libraries/BouncyCastle.Crypto/Org/BouncyCastle/Math/EC/AbstractF2mCurve.cs

@@ -0,0 +1,180 @@
+using System;
+using Org.BouncyCastle.Math.EC.Abc;
+using Org.BouncyCastle.Math.Field;
+
+namespace Org.BouncyCastle.Math.EC;
+
+public abstract class AbstractF2mCurve : ECCurve
+{
+	private BigInteger[] si = null;
+
+	public virtual bool IsKoblitz
+	{
+		get
+		{
+			if (m_order != null && m_cofactor != null && m_b.IsOne)
+			{
+				if (!m_a.IsZero)
+				{
+					return m_a.IsOne;
+				}
+				return true;
+			}
+			return false;
+		}
+	}
+
+	public static BigInteger Inverse(int m, int[] ks, BigInteger x)
+	{
+		return new LongArray(x).ModInverse(m, ks).ToBigInteger();
+	}
+
+	private static IFiniteField BuildField(int m, int k1, int k2, int k3)
+	{
+		if (k1 == 0)
+		{
+			throw new ArgumentException("k1 must be > 0");
+		}
+		if (k2 == 0)
+		{
+			if (k3 != 0)
+			{
+				throw new ArgumentException("k3 must be 0 if k2 == 0");
+			}
+			return FiniteFields.GetBinaryExtensionField(new int[3] { 0, k1, m });
+		}
+		if (k2 <= k1)
+		{
+			throw new ArgumentException("k2 must be > k1");
+		}
+		if (k3 <= k2)
+		{
+			throw new ArgumentException("k3 must be > k2");
+		}
+		return FiniteFields.GetBinaryExtensionField(new int[5] { 0, k1, k2, k3, m });
+	}
+
+	protected AbstractF2mCurve(int m, int k1, int k2, int k3)
+		: base(BuildField(m, k1, k2, k3))
+	{
+	}
+
+	public override bool IsValidFieldElement(BigInteger x)
+	{
+		if (x != null && x.SignValue >= 0)
+		{
+			return x.BitLength <= FieldSize;
+		}
+		return false;
+	}
+
+	[Obsolete("Per-point compression property will be removed")]
+	public override ECPoint CreatePoint(BigInteger x, BigInteger y, bool withCompression)
+	{
+		ECFieldElement eCFieldElement = FromBigInteger(x);
+		ECFieldElement eCFieldElement2 = FromBigInteger(y);
+		switch (CoordinateSystem)
+		{
+		case 5:
+		case 6:
+			if (eCFieldElement.IsZero)
+			{
+				if (!eCFieldElement2.Square().Equals(B))
+				{
+					throw new ArgumentException();
+				}
+			}
+			else
+			{
+				eCFieldElement2 = eCFieldElement2.Divide(eCFieldElement).Add(eCFieldElement);
+			}
+			break;
+		}
+		return CreateRawPoint(eCFieldElement, eCFieldElement2, withCompression);
+	}
+
+	protected override ECPoint DecompressPoint(int yTilde, BigInteger X1)
+	{
+		ECFieldElement eCFieldElement = FromBigInteger(X1);
+		ECFieldElement eCFieldElement2 = null;
+		if (eCFieldElement.IsZero)
+		{
+			eCFieldElement2 = B.Sqrt();
+		}
+		else
+		{
+			ECFieldElement beta = eCFieldElement.Square().Invert().Multiply(B)
+				.Add(A)
+				.Add(eCFieldElement);
+			ECFieldElement eCFieldElement3 = SolveQuadraticEquation(beta);
+			if (eCFieldElement3 != null)
+			{
+				if (eCFieldElement3.TestBitZero() != (yTilde == 1))
+				{
+					eCFieldElement3 = eCFieldElement3.AddOne();
+				}
+				switch (CoordinateSystem)
+				{
+				case 5:
+				case 6:
+					eCFieldElement2 = eCFieldElement3.Add(eCFieldElement);
+					break;
+				default:
+					eCFieldElement2 = eCFieldElement3.Multiply(eCFieldElement);
+					break;
+				}
+			}
+		}
+		if (eCFieldElement2 == null)
+		{
+			throw new ArgumentException("Invalid point compression");
+		}
+		return CreateRawPoint(eCFieldElement, eCFieldElement2, withCompression: true);
+	}
+
+	internal ECFieldElement SolveQuadraticEquation(ECFieldElement beta)
+	{
+		if (beta.IsZero)
+		{
+			return beta;
+		}
+		ECFieldElement eCFieldElement = FromBigInteger(BigInteger.Zero);
+		int fieldSize = FieldSize;
+		ECFieldElement eCFieldElement2;
+		ECFieldElement eCFieldElement5;
+		do
+		{
+			ECFieldElement b = FromBigInteger(BigInteger.Arbitrary(fieldSize));
+			eCFieldElement2 = eCFieldElement;
+			ECFieldElement eCFieldElement3 = beta;
+			for (int i = 1; i < fieldSize; i++)
+			{
+				ECFieldElement eCFieldElement4 = eCFieldElement3.Square();
+				eCFieldElement2 = eCFieldElement2.Square().Add(eCFieldElement4.Multiply(b));
+				eCFieldElement3 = eCFieldElement4.Add(beta);
+			}
+			if (!eCFieldElement3.IsZero)
+			{
+				return null;
+			}
+			eCFieldElement5 = eCFieldElement2.Square().Add(eCFieldElement2);
+		}
+		while (eCFieldElement5.IsZero);
+		return eCFieldElement2;
+	}
+
+	internal virtual BigInteger[] GetSi()
+	{
+		if (si == null)
+		{
+			lock (this)
+			{
+				if (si == null)
+				{
+					si = Tnaf.GetSi(this);
+				}
+			}
+		}
+		return si;
+	}
+}