F2mCurve
using Org.BouncyCastle.Math.EC.Multiplier;
using System;
namespace Org.BouncyCastle.Math.EC
{
public class F2mCurve : AbstractF2mCurve
{
private class DefaultF2mLookupTable : AbstractECLookupTable
{
private readonly F2mCurve m_outer;
private readonly ulong[] m_table;
private readonly int m_size;
public override int Size => m_size;
internal DefaultF2mLookupTable(F2mCurve outer, ulong[] table, int size)
{
m_outer = outer;
m_table = table;
m_size = size;
}
public override ECPoint Lookup(int index)
{
int num = (m_outer.m + 63) / 64;
ulong[] array = new ulong[num];
ulong[] array2 = new ulong[num];
int num2 = 0;
for (int i = 0; i < m_size; i++) {
ulong num3 = (ulong)((i ^ index) - 1 >> 31);
for (int j = 0; j < num; j++) {
array[j] ^= (m_table[num2 + j] & num3);
array2[j] ^= (m_table[num2 + num + j] & num3);
}
num2 += num * 2;
}
return CreatePoint(array, array2);
}
public override ECPoint LookupVar(int index)
{
int num = (m_outer.m + 63) / 64;
ulong[] array = new ulong[num];
ulong[] array2 = new ulong[num];
int num2 = index * num * 2;
for (int i = 0; i < num; i++) {
array[i] = m_table[num2 + i];
array2[i] = m_table[num2 + num + i];
}
return CreatePoint(array, array2);
}
private ECPoint CreatePoint(ulong[] x, ulong[] y)
{
int m = m_outer.m;
int[] ks = (!m_outer.IsTrinomial()) ? new int[3] {
m_outer.k1,
m_outer.k2,
m_outer.k3
} : new int[1] {
m_outer.k1
};
ECFieldElement x2 = new F2mFieldElement(m, ks, new LongArray(x));
ECFieldElement y2 = new F2mFieldElement(m, ks, new LongArray(y));
return m_outer.CreateRawPoint(x2, y2);
}
}
private const int F2M_DEFAULT_COORDS = 6;
private readonly int m;
private readonly int k1;
private readonly int k2;
private readonly int k3;
protected readonly F2mPoint m_infinity;
public override int FieldSize => m;
public override ECPoint Infinity => m_infinity;
public int M => m;
public int K1 => k1;
public int K2 => k2;
public int K3 => k3;
[Obsolete("Use constructor taking order/cofactor")]
public F2mCurve(int m, int k, BigInteger a, BigInteger b)
: this(m, k, 0, 0, a, b, null, null)
{
}
public F2mCurve(int m, int k, BigInteger a, BigInteger b, BigInteger order, BigInteger cofactor)
: this(m, k, 0, 0, a, b, order, cofactor)
{
}
[Obsolete("Use constructor taking order/cofactor")]
public F2mCurve(int m, int k1, int k2, int k3, BigInteger a, BigInteger b)
: this(m, k1, k2, k3, a, b, null, null)
{
}
public F2mCurve(int m, int k1, int k2, int k3, BigInteger a, BigInteger b, BigInteger order, BigInteger cofactor)
: base(m, k1, k2, k3)
{
this.m = m;
this.k1 = k1;
this.k2 = k2;
this.k3 = k3;
m_order = order;
m_cofactor = cofactor;
m_infinity = new F2mPoint(this, null, null);
m_a = FromBigInteger(a);
m_b = FromBigInteger(b);
m_coord = 6;
}
internal F2mCurve(int m, int k1, int k2, int k3, ECFieldElement a, ECFieldElement b, BigInteger order, BigInteger cofactor)
: base(m, k1, k2, k3)
{
this.m = m;
this.k1 = k1;
this.k2 = k2;
this.k3 = k3;
m_order = order;
m_cofactor = cofactor;
m_infinity = new F2mPoint(this, null, null);
m_a = a;
m_b = b;
m_coord = 6;
}
protected override ECCurve CloneCurve()
{
return new F2mCurve(m, k1, k2, k3, m_a, m_b, m_order, m_cofactor);
}
public override bool SupportsCoordinateSystem(int coord)
{
if ((uint)coord <= 1 || coord == 6)
return true;
return false;
}
protected override ECMultiplier CreateDefaultMultiplier()
{
if (IsKoblitz)
return new WTauNafMultiplier();
return base.CreateDefaultMultiplier();
}
public override ECFieldElement FromBigInteger(BigInteger x)
{
if (x == null || x.SignValue < 0 || x.BitLength > m)
throw new ArgumentException("value invalid for F2m field element", "x");
int[] ks = ((k2 | k3) != 0) ? new int[3] {
k1,
k2,
k3
} : new int[1] {
k1
};
return new F2mFieldElement(m, ks, new LongArray(x));
}
protected internal override ECPoint CreateRawPoint(ECFieldElement x, ECFieldElement y)
{
return new F2mPoint(this, x, y);
}
protected internal override ECPoint CreateRawPoint(ECFieldElement x, ECFieldElement y, ECFieldElement[] zs)
{
return new F2mPoint(this, x, y, zs);
}
public bool IsTrinomial()
{
if (k2 == 0)
return k3 == 0;
return false;
}
public override ECLookupTable CreateCacheSafeLookupTable(ECPoint[] points, int off, int len)
{
int num = (m + 63) / 64;
ulong[] array = new ulong[len * num * 2];
int num2 = 0;
for (int i = 0; i < len; i++) {
ECPoint obj = points[off + i];
((F2mFieldElement)obj.RawXCoord).x.CopyTo(array, num2);
num2 += num;
((F2mFieldElement)obj.RawYCoord).x.CopyTo(array, num2);
num2 += num;
}
return new DefaultF2mLookupTable(this, array, len);
}
}
}