SecP256K1Field
class SecP256K1Field
using Org.BouncyCastle.Crypto.Utilities;
using Org.BouncyCastle.Math.Raw;
using Org.BouncyCastle.Security;
namespace Org.BouncyCastle.Math.EC.Custom.Sec
{
internal class SecP256K1Field
{
internal static readonly uint[] P = new uint[8] {
4294966319,
4294967294,
uint.MaxValue,
uint.MaxValue,
uint.MaxValue,
uint.MaxValue,
uint.MaxValue,
uint.MaxValue
};
private static readonly uint[] PExt = new uint[16] {
954529,
1954,
1,
0,
0,
0,
0,
0,
4294965342,
4294967293,
uint.MaxValue,
uint.MaxValue,
uint.MaxValue,
uint.MaxValue,
uint.MaxValue,
uint.MaxValue
};
private static readonly uint[] PExtInv = new uint[10] {
4294012767,
4294965341,
4294967294,
uint.MaxValue,
uint.MaxValue,
uint.MaxValue,
uint.MaxValue,
uint.MaxValue,
1953,
2
};
private const uint P7 = uint.MaxValue;
private const uint PExt15 = uint.MaxValue;
private const uint PInv33 = 977;
public static void Add(uint[] x, uint[] y, uint[] z)
{
if (Nat256.Add(x, y, z) != 0 || (z[7] == uint.MaxValue && Nat256.Gte(z, P)))
Nat.Add33To(8, 977, z);
}
public static void AddExt(uint[] xx, uint[] yy, uint[] zz)
{
if ((Nat.Add(16, xx, yy, zz) != 0 || (zz[15] == uint.MaxValue && Nat.Gte(16, zz, PExt))) && Nat.AddTo(PExtInv.Length, PExtInv, zz) != 0)
Nat.IncAt(16, zz, PExtInv.Length);
}
public static void AddOne(uint[] x, uint[] z)
{
if (Nat.Inc(8, x, z) != 0 || (z[7] == uint.MaxValue && Nat256.Gte(z, P)))
Nat.Add33To(8, 977, z);
}
public static uint[] FromBigInteger(BigInteger x)
{
uint[] array = Nat.FromBigInteger(256, x);
if (array[7] == uint.MaxValue && Nat256.Gte(array, P))
Nat256.SubFrom(P, array, 0);
return array;
}
public static void Half(uint[] x, uint[] z)
{
if ((x[0] & 1) == 0)
Nat.ShiftDownBit(8, x, 0, z);
else {
uint c = Nat256.Add(x, P, z);
Nat.ShiftDownBit(8, z, c);
}
}
public static void Inv(uint[] x, uint[] z)
{
Mod.CheckedModOddInverse(P, x, z);
}
public static int IsZero(uint[] x)
{
uint num = 0;
for (int i = 0; i < 8; i++) {
num |= x[i];
}
num = ((num >> 1) | (num & 1));
return (int)(num - 1) >> 31;
}
public static void Multiply(uint[] x, uint[] y, uint[] z)
{
uint[] array = Nat256.CreateExt();
Nat256.Mul(x, y, array);
Reduce(array, z);
}
public static void Multiply(uint[] x, uint[] y, uint[] z, uint[] tt)
{
Nat256.Mul(x, y, tt);
Reduce(tt, z);
}
public static void MultiplyAddToExt(uint[] x, uint[] y, uint[] zz)
{
if ((Nat256.MulAddTo(x, y, zz) != 0 || (zz[15] == uint.MaxValue && Nat.Gte(16, zz, PExt))) && Nat.AddTo(PExtInv.Length, PExtInv, zz) != 0)
Nat.IncAt(16, zz, PExtInv.Length);
}
public static void Negate(uint[] x, uint[] z)
{
if (IsZero(x) != 0)
Nat256.Sub(P, P, z);
else
Nat256.Sub(P, x, z);
}
public static void Random(SecureRandom r, uint[] z)
{
byte[] array = new byte[32];
do {
r.NextBytes(array);
Pack.LE_To_UInt32(array, 0, z, 0, 8);
} while (Nat.LessThan(8, z, P) == 0);
}
public static void RandomMult(SecureRandom r, uint[] z)
{
do {
Random(r, z);
} while (IsZero(z) != 0);
}
public static void Reduce(uint[] xx, uint[] z)
{
ulong y = Nat256.Mul33Add(977, xx, 8, xx, 0, z, 0);
if (Nat256.Mul33DWordAdd(977, y, z, 0) != 0 || (z[7] == uint.MaxValue && Nat256.Gte(z, P)))
Nat.Add33To(8, 977, z);
}
public static void Reduce32(uint x, uint[] z)
{
if ((x != 0 && Nat256.Mul33WordAdd(977, x, z, 0) != 0) || (z[7] == uint.MaxValue && Nat256.Gte(z, P)))
Nat.Add33To(8, 977, z);
}
public static void Square(uint[] x, uint[] z)
{
uint[] array = Nat256.CreateExt();
Nat256.Square(x, array);
Reduce(array, z);
}
public static void Square(uint[] x, uint[] z, uint[] tt)
{
Nat256.Square(x, tt);
Reduce(tt, z);
}
public static void SquareN(uint[] x, int n, uint[] z)
{
uint[] array = Nat256.CreateExt();
Nat256.Square(x, array);
Reduce(array, z);
while (--n > 0) {
Nat256.Square(z, array);
Reduce(array, z);
}
}
public static void SquareN(uint[] x, int n, uint[] z, uint[] tt)
{
Nat256.Square(x, tt);
Reduce(tt, z);
while (--n > 0) {
Nat256.Square(z, tt);
Reduce(tt, z);
}
}
public static void Subtract(uint[] x, uint[] y, uint[] z)
{
if (Nat256.Sub(x, y, z) != 0)
Nat.Sub33From(8, 977, z);
}
public static void SubtractExt(uint[] xx, uint[] yy, uint[] zz)
{
if (Nat.Sub(16, xx, yy, zz) != 0 && Nat.SubFrom(PExtInv.Length, PExtInv, zz) != 0)
Nat.DecAt(16, zz, PExtInv.Length);
}
public static void Twice(uint[] x, uint[] z)
{
if (Nat.ShiftUpBit(8, x, 0, z) != 0 || (z[7] == uint.MaxValue && Nat256.Gte(z, P)))
Nat.Add33To(8, 977, z);
}
}
}