Hrss1373Polynomial
using Org.BouncyCastle.Pqc.Crypto.Ntru.ParameterSets;
using System;
namespace Org.BouncyCastle.Pqc.Crypto.Ntru.Polynomials
{
internal class Hrss1373Polynomial : HrssPolynomial
{
private static readonly int L = 1376;
private static readonly int M = L / 4;
private static readonly int K = L / 16;
internal Hrss1373Polynomial(NtruHrssParameterSet parameters)
: base(parameters)
{
}
public unsafe override byte[] SqToBytes(int len)
{
byte[] array = new byte[len];
Span<short> span = new Span<short>(stackalloc byte[8], 4);
int i;
for (i = 0; i < ParameterSet.PackDegree() / 4; i++) {
for (int j = 0; j < 4; j++) {
span[j] = (short)Polynomial.ModQ((uint)(coeffs[4 * i + j] & 65535), (uint)ParameterSet.Q());
}
array[7 * i] = (byte)(span[0] & 255);
array[7 * i + 1] = (byte)((span[0] >> 8) | ((span[1] & 3) << 6));
array[7 * i + 2] = (byte)((span[1] >> 2) & 255);
array[7 * i + 3] = (byte)((span[1] >> 10) | ((span[2] & 15) << 4));
array[7 * i + 4] = (byte)((span[2] >> 4) & 255);
array[7 * i + 5] = (byte)((span[2] >> 12) | ((span[3] & 63) << 2));
array[7 * i + 6] = (byte)(span[3] >> 6);
}
if (ParameterSet.PackDegree() % 4 == 2) {
span[0] = (short)Polynomial.ModQ((uint)(coeffs[ParameterSet.PackDegree() - 2] & 65535), (uint)ParameterSet.Q());
span[1] = (short)Polynomial.ModQ((uint)(coeffs[ParameterSet.PackDegree() - 1] & 65535), (uint)ParameterSet.Q());
array[7 * i] = (byte)(span[0] & 255);
array[7 * i + 1] = (byte)((span[0] >> 8) | ((span[1] & 3) << 6));
array[7 * i + 2] = (byte)((span[1] >> 2) & 255);
array[7 * i + 3] = (byte)(span[1] >> 10);
}
return array;
}
public override void SqFromBytes(byte[] a)
{
int i;
for (i = 0; i < ParameterSet.PackDegree() / 4; i++) {
coeffs[4 * i] = (ushort)((a[7 * i] & 255) | (((ushort)(a[7 * i + 1] & 255) & 63) << 8));
coeffs[4 * i + 1] = (ushort)(((a[7 * i + 1] & 255) >> 6) | ((ushort)(a[7 * i + 2] & 255) << 2) | ((short)(a[7 * i + 3] & 15) << 10));
coeffs[4 * i + 2] = (ushort)(((a[7 * i + 3] & 255) >> 4) | (((ushort)(a[7 * i + 4] & 255) & 255) << 4) | ((short)(a[7 * i + 5] & 3) << 12));
coeffs[4 * i + 3] = (ushort)(((a[7 * i + 5] & 255) >> 2) | ((ushort)(a[7 * i + 6] & 255) << 6));
}
if (ParameterSet.PackDegree() % 4 == 2) {
coeffs[4 * i] = (ushort)(a[7 * i] | ((a[7 * i + 1] & 63) << 8));
coeffs[4 * i + 1] = (ushort)((a[7 * i + 1] >> 6) | (a[7 * i + 2] << 2) | ((a[7 * i + 3] & 15) << 10));
}
coeffs[ParameterSet.N - 1] = 0;
}
}
}