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using System;
using Org.BouncyCastle.Crypto.Utilities;
using Org.BouncyCastle.Utilities;
namespace Org.BouncyCastle.Crypto.Modes.Gcm
{
public class Tables8kGcmMultiplier
: IGcmMultiplier
{
private byte[] H;
private GcmUtilities.FieldElement[][] T;
public void Init(byte[] H)
{
if (T == null)
{
T = new GcmUtilities.FieldElement[2][];
}
else if (Arrays.AreEqual(this.H, H))
{
return;
}
this.H = Arrays.Clone(H);
for (int i = 0; i < 2; ++i)
{
GcmUtilities.FieldElement[] t = T[i] = new GcmUtilities.FieldElement[256];
// t[0] = 0
if (i == 0)
{
// t[1] = H.p^7
GcmUtilities.AsFieldElement(this.H, out t[1]);
GcmUtilities.MultiplyP7(ref t[1]);
}
else
{
// t[1] = T[i-1][1].p^8
GcmUtilities.MultiplyP8(ref T[i - 1][1], out t[1]);
}
for (int n = 1; n < 128; ++n)
{
// t[2.n] = t[n].p^-1
GcmUtilities.DivideP(ref t[n], out t[n << 1]);
// t[2.n + 1] = t[2.n] + t[1]
GcmUtilities.Xor(ref t[n << 1], ref t[1], out t[(n << 1) + 1]);
}
}
}
public void MultiplyH(byte[] x)
{
GcmUtilities.FieldElement[] T0 = T[0], T1 = T[1];
//GcmUtilities.FieldElement z;
//GcmUtilities.Xor(ref T0[x[14]], ref T1[x[15]], out z);
//for (int i = 12; i >= 0; i -= 2)
//{
// GcmUtilities.MultiplyP16(ref z);
// GcmUtilities.Xor(ref z, ref T0[x[i]]);
// GcmUtilities.Xor(ref z, ref T1[x[i + 1]]);
//}
//GcmUtilities.AsBytes(ref z, x);
int vPos = x[15];
int uPos = x[14];
ulong z1 = T0[uPos].n1 ^ T1[vPos].n1;
ulong z0 = T0[uPos].n0 ^ T1[vPos].n0;
for (int i = 12; i >= 0; i -= 2)
{
vPos = x[i + 1];
uPos = x[i];
ulong c = z1 << 48;
z1 = T0[uPos].n1 ^ T1[vPos].n1 ^ ((z1 >> 16) | (z0 << 48));
z0 = T0[uPos].n0 ^ T1[vPos].n0 ^ (z0 >> 16) ^ c ^ (c >> 1) ^ (c >> 2) ^ (c >> 7);
}
Pack.UInt64_To_BE(z0, x, 0);
Pack.UInt64_To_BE(z1, x, 8);
}
}
}
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