public static void ScalarMult(byte[] k, int kOff, byte[] u, int uOff, byte[] r, int rOff)
{
uint[] n = new uint[14]; DecodeScalar(k, kOff, n);
uint[] x1 = X448Field.Create(); X448Field.Decode(u, uOff, x1);
uint[] x2 = X448Field.Create(); X448Field.Copy(x1, 0, x2, 0);
uint[] z2 = X448Field.Create(); z2[0] = 1;
uint[] x3 = X448Field.Create(); x3[0] = 1;
uint[] z3 = X448Field.Create();
uint[] t1 = X448Field.Create();
uint[] t2 = X448Field.Create();
Debug.Assert(n[13] >> 31 == 1U);
int bit = 447, swap = 1;
do
{
//X448Field.Apm(x3, z3, t1, x3);
X448Field.Add(x3, z3, t1);
X448Field.Sub(x3, z3, x3);
//X448Field.Apm(x2, z2, z3, x2);
X448Field.Add(x2, z2, z3);
X448Field.Sub(x2, z2, x2);
X448Field.Mul(t1, x2, t1);
X448Field.Mul(x3, z3, x3);
X448Field.Sqr(z3, z3);
X448Field.Sqr(x2, x2);
X448Field.Sub(z3, x2, t2);
X448Field.Mul(t2, C_A24, z2);
X448Field.Add(z2, x2, z2);
X448Field.Mul(z2, t2, z2);
X448Field.Mul(x2, z3, x2);
//X448Field.Apm(t1, x3, x3, z3);
X448Field.Sub(t1, x3, z3);
X448Field.Add(t1, x3, x3);
X448Field.Sqr(x3, x3);
X448Field.Sqr(z3, z3);
X448Field.Mul(z3, x1, z3);
--bit;
int word = bit >> 5, shift = bit & 0x1F;
int kt = (int)(n[word] >> shift) & 1;
swap ^= kt;
X448Field.CSwap(swap, x2, x3);
X448Field.CSwap(swap, z2, z3);
swap = kt;
}while (bit >= 2);
Debug.Assert(swap == 0);
for (int i = 0; i < 2; ++i)
{
PointDouble(x2, z2);
}
X448Field.Inv(z2, z2);
X448Field.Mul(x2, z2, x2);
X448Field.Normalize(x2);
X448Field.Encode(x2, r, rOff);
}
