init commit

output/Libraries/BouncyCastle.Crypto/Org/BouncyCastle/Math/Field/FiniteFields.cs

@@ -0,0 +1,46 @@
+using System;
+
+namespace Org.BouncyCastle.Math.Field;
+
+public abstract class FiniteFields
+{
+	internal static readonly IFiniteField GF_2 = new PrimeField(BigInteger.ValueOf(2L));
+
+	internal static readonly IFiniteField GF_3 = new PrimeField(BigInteger.ValueOf(3L));
+
+	public static IPolynomialExtensionField GetBinaryExtensionField(int[] exponents)
+	{
+		if (exponents[0] != 0)
+		{
+			throw new ArgumentException("Irreducible polynomials in GF(2) must have constant term", "exponents");
+		}
+		for (int i = 1; i < exponents.Length; i++)
+		{
+			if (exponents[i] <= exponents[i - 1])
+			{
+				throw new ArgumentException("Polynomial exponents must be montonically increasing", "exponents");
+			}
+		}
+		return new GenericPolynomialExtensionField(GF_2, new GF2Polynomial(exponents));
+	}
+
+	public static IFiniteField GetPrimeField(BigInteger characteristic)
+	{
+		int bitLength = characteristic.BitLength;
+		if (characteristic.SignValue <= 0 || bitLength < 2)
+		{
+			throw new ArgumentException("Must be >= 2", "characteristic");
+		}
+		if (bitLength < 3)
+		{
+			switch (characteristic.IntValue)
+			{
+			case 2:
+				return GF_2;
+			case 3:
+				return GF_3;
+			}
+		}
+		return new PrimeField(characteristic);
+	}
+}

output/Libraries/BouncyCastle.Crypto/Org/BouncyCastle/Math/Field/GF2Polynomial.cs

@@ -0,0 +1,38 @@
+using Org.BouncyCastle.Utilities;
+
+namespace Org.BouncyCastle.Math.Field;
+
+internal class GF2Polynomial : IPolynomial
+{
+	protected readonly int[] exponents;
+
+	public virtual int Degree => exponents[exponents.Length - 1];
+
+	internal GF2Polynomial(int[] exponents)
+	{
+		this.exponents = Arrays.Clone(exponents);
+	}
+
+	public virtual int[] GetExponentsPresent()
+	{
+		return Arrays.Clone(exponents);
+	}
+
+	public override bool Equals(object obj)
+	{
+		if (this == obj)
+		{
+			return true;
+		}
+		if (!(obj is GF2Polynomial gF2Polynomial))
+		{
+			return false;
+		}
+		return Arrays.AreEqual(exponents, gF2Polynomial.exponents);
+	}
+
+	public override int GetHashCode()
+	{
+		return Arrays.GetHashCode(exponents);
+	}
+}

output/Libraries/BouncyCastle.Crypto/Org/BouncyCastle/Math/Field/GenericPolynomialExtensionField.cs

@@ -0,0 +1,48 @@
+using Org.BouncyCastle.Utilities;
+
+namespace Org.BouncyCastle.Math.Field;
+
+internal class GenericPolynomialExtensionField : IPolynomialExtensionField, IExtensionField, IFiniteField
+{
+	protected readonly IFiniteField subfield;
+
+	protected readonly IPolynomial minimalPolynomial;
+
+	public virtual BigInteger Characteristic => subfield.Characteristic;
+
+	public virtual int Dimension => subfield.Dimension * minimalPolynomial.Degree;
+
+	public virtual IFiniteField Subfield => subfield;
+
+	public virtual int Degree => minimalPolynomial.Degree;
+
+	public virtual IPolynomial MinimalPolynomial => minimalPolynomial;
+
+	internal GenericPolynomialExtensionField(IFiniteField subfield, IPolynomial polynomial)
+	{
+		this.subfield = subfield;
+		minimalPolynomial = polynomial;
+	}
+
+	public override bool Equals(object obj)
+	{
+		if (this == obj)
+		{
+			return true;
+		}
+		if (!(obj is GenericPolynomialExtensionField genericPolynomialExtensionField))
+		{
+			return false;
+		}
+		if (subfield.Equals(genericPolynomialExtensionField.subfield))
+		{
+			return minimalPolynomial.Equals(genericPolynomialExtensionField.minimalPolynomial);
+		}
+		return false;
+	}
+
+	public override int GetHashCode()
+	{
+		return subfield.GetHashCode() ^ Integers.RotateLeft(minimalPolynomial.GetHashCode(), 16);
+	}
+}

output/Libraries/BouncyCastle.Crypto/Org/BouncyCastle/Math/Field/IExtensionField.cs

@@ -0,0 +1,8 @@
+namespace Org.BouncyCastle.Math.Field;
+
+public interface IExtensionField : IFiniteField
+{
+	IFiniteField Subfield { get; }
+
+	int Degree { get; }
+}

output/Libraries/BouncyCastle.Crypto/Org/BouncyCastle/Math/Field/IFiniteField.cs

@@ -0,0 +1,8 @@
+namespace Org.BouncyCastle.Math.Field;
+
+public interface IFiniteField
+{
+	BigInteger Characteristic { get; }
+
+	int Dimension { get; }
+}

output/Libraries/BouncyCastle.Crypto/Org/BouncyCastle/Math/Field/IPolynomial.cs

@@ -0,0 +1,8 @@
+namespace Org.BouncyCastle.Math.Field;
+
+public interface IPolynomial
+{
+	int Degree { get; }
+
+	int[] GetExponentsPresent();
+}

output/Libraries/BouncyCastle.Crypto/Org/BouncyCastle/Math/Field/IPolynomialExtensionField.cs

@@ -0,0 +1,6 @@
+namespace Org.BouncyCastle.Math.Field;
+
+public interface IPolynomialExtensionField : IExtensionField, IFiniteField
+{
+	IPolynomial MinimalPolynomial { get; }
+}

output/Libraries/BouncyCastle.Crypto/Org/BouncyCastle/Math/Field/PrimeField.cs

@@ -0,0 +1,33 @@
+namespace Org.BouncyCastle.Math.Field;
+
+internal class PrimeField : IFiniteField
+{
+	protected readonly BigInteger characteristic;
+
+	public virtual BigInteger Characteristic => characteristic;
+
+	public virtual int Dimension => 1;
+
+	internal PrimeField(BigInteger characteristic)
+	{
+		this.characteristic = characteristic;
+	}
+
+	public override bool Equals(object obj)
+	{
+		if (this == obj)
+		{
+			return true;
+		}
+		if (!(obj is PrimeField primeField))
+		{
+			return false;
+		}
+		return characteristic.Equals(primeField.characteristic);
+	}
+
+	public override int GetHashCode()
+	{
+		return characteristic.GetHashCode();
+	}
+}