org.bouncycastle.crypto.modes.gcm.Tables4kGCMMultiplier Maven / Gradle / Ivy
package org.bouncycastle.crypto.modes.gcm;
import org.bouncycastle.util.Arrays;
import org.bouncycastle.util.Pack;
public class Tables4kGCMMultiplier
implements GCMMultiplier
{
private byte[] H;
private long[][] T;
public void init(byte[] H)
{
if (T == null)
{
T = new long[256][2];
}
else if (Arrays.areEqual(this.H, H))
{
return;
}
this.H = Arrays.clone(H);
// T[0] = 0
// T[1] = H.p^7
GCMUtil.asLongs(this.H, T[1]);
GCMUtil.multiplyP7(T[1], T[1]);
for (int n = 2; n < 256; n += 2)
{
// T[2.n] = T[n].p^-1
GCMUtil.divideP(T[n >> 1], T[n]);
// T[2.n + 1] = T[2.n] + T[1]
GCMUtil.xor(T[n], T[1], T[n + 1]);
}
}
public void multiplyH(byte[] x)
{
// long[] z = new long[2];
// GCMUtil.copy(T[x[15] & 0xFF], z);
// for (int i = 14; i >= 0; --i)
// {
// GCMUtil.multiplyP8(z);
// GCMUtil.xor(z, T[x[i] & 0xFF]);
// }
// Pack.longToBigEndian(z, x, 0);
long[] t = T[x[15] & 0xFF];
long z0 = t[0], z1 = t[1];
for (int i = 14; i >= 0; --i)
{
t = T[x[i] & 0xFF];
long c = z1 << 56;
z1 = t[1] ^ ((z1 >>> 8) | (z0 << 56));
z0 = t[0] ^ (z0 >>> 8) ^ c ^ (c >>> 1) ^ (c >>> 2) ^ (c >>> 7);
}
Pack.longToBigEndian(z0, x, 0);
Pack.longToBigEndian(z1, x, 8);
}
}