SecP256K1Curve
using Org.BouncyCastle.Math.Raw;
using Org.BouncyCastle.Security;
using Org.BouncyCastle.Utilities.Encoders;
namespace Org.BouncyCastle.Math.EC.Custom.Sec
{
internal class SecP256K1Curve : AbstractFpCurve
{
private class SecP256K1LookupTable : AbstractECLookupTable
{
private readonly SecP256K1Curve m_outer;
private readonly uint[] m_table;
private readonly int m_size;
public override int Size => m_size;
internal SecP256K1LookupTable(SecP256K1Curve outer, uint[] table, int size)
{
m_outer = outer;
m_table = table;
m_size = size;
}
public override ECPoint Lookup(int index)
{
uint[] array = Nat256.Create();
uint[] array2 = Nat256.Create();
int num = 0;
for (int i = 0; i < m_size; i++) {
uint num2 = (uint)((i ^ index) - 1 >> 31);
for (int j = 0; j < 8; j++) {
array[j] ^= (m_table[num + j] & num2);
array2[j] ^= (m_table[num + 8 + j] & num2);
}
num += 16;
}
return CreatePoint(array, array2);
}
public override ECPoint LookupVar(int index)
{
uint[] array = Nat256.Create();
uint[] array2 = Nat256.Create();
int num = index * 8 * 2;
for (int i = 0; i < 8; i++) {
array[i] = m_table[num + i];
array2[i] = m_table[num + 8 + i];
}
return CreatePoint(array, array2);
}
private ECPoint CreatePoint(uint[] x, uint[] y)
{
return m_outer.CreateRawPoint(new SecP256K1FieldElement(x), new SecP256K1FieldElement(y), SECP256K1_AFFINE_ZS);
}
}
public static readonly BigInteger q = SecP256K1FieldElement.Q;
private const int SECP256K1_DEFAULT_COORDS = 2;
private const int SECP256K1_FE_INTS = 8;
private static readonly ECFieldElement[] SECP256K1_AFFINE_ZS = new ECFieldElement[1] {
new SecP256K1FieldElement(BigInteger.One)
};
protected readonly SecP256K1Point m_infinity;
public virtual BigInteger Q => q;
public override ECPoint Infinity => m_infinity;
public override int FieldSize => q.BitLength;
public SecP256K1Curve()
: base(q, true)
{
m_infinity = new SecP256K1Point(this, null, null);
m_a = FromBigInteger(BigInteger.Zero);
m_b = FromBigInteger(BigInteger.ValueOf(7));
m_order = new BigInteger(1, Hex.DecodeStrict("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141"));
m_cofactor = BigInteger.One;
m_coord = 2;
}
protected override ECCurve CloneCurve()
{
return new SecP256K1Curve();
}
public override bool SupportsCoordinateSystem(int coord)
{
if (coord == 2)
return true;
return false;
}
public override ECFieldElement FromBigInteger(BigInteger x)
{
return new SecP256K1FieldElement(x);
}
protected internal override ECPoint CreateRawPoint(ECFieldElement x, ECFieldElement y)
{
return new SecP256K1Point(this, x, y);
}
protected internal override ECPoint CreateRawPoint(ECFieldElement x, ECFieldElement y, ECFieldElement[] zs)
{
return new SecP256K1Point(this, x, y, zs);
}
public override ECLookupTable CreateCacheSafeLookupTable(ECPoint[] points, int off, int len)
{
uint[] array = new uint[len * 8 * 2];
int num = 0;
for (int i = 0; i < len; i++) {
ECPoint obj = points[off + i];
Nat256.Copy(((SecP256K1FieldElement)obj.RawXCoord).x, 0, array, num);
num += 8;
Nat256.Copy(((SecP256K1FieldElement)obj.RawYCoord).x, 0, array, num);
num += 8;
}
return new SecP256K1LookupTable(this, array, len);
}
public override ECFieldElement RandomFieldElement(SecureRandom r)
{
uint[] array = Nat256.Create();
SecP256K1Field.Random(r, array);
return new SecP256K1FieldElement(array);
}
public override ECFieldElement RandomFieldElementMult(SecureRandom r)
{
uint[] array = Nat256.Create();
SecP256K1Field.RandomMult(r, array);
return new SecP256K1FieldElement(array);
}
}
}