org.bouncycastle.crypto.modes.gcm.Tables64kGCMMultiplier Maven / Gradle / Ivy

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The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.8 and up.

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package org.bouncycastle.crypto.modes.gcm;

import org.bouncycastle.util.Pack;

public class Tables64kGCMMultiplier
    implements GCMMultiplier
{
    private byte[] H;
    private long[][][] T;

    public void init(byte[] H)
    {
        if (T == null)
        {
            T = new long[16][256][2];
        }
        else if (0 != GCMUtil.areEqual(this.H, H))
        {
            return;
        }

        this.H = new byte[GCMUtil.SIZE_BYTES];
        GCMUtil.copy(H, this.H);

        for (int i = 0; i < 16; ++i)
        {
            long[][] t = T[i];

            // t[0] = 0

            if (i == 0)
            {
                // t[1] = H.p^7
                GCMUtil.asLongs(this.H, t[1]);
                GCMUtil.multiplyP7(t[1], t[1]);
            }
            else
            {
                // t[1] = T[i-1][1].p^8
                GCMUtil.multiplyP8(T[i - 1][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];
//        for (int i = 15; i >= 0; --i)
//        {
//            GCMUtil.xor(z, T[i][x[i] & 0xFF]);
//        }
//        Pack.longToBigEndian(z, x, 0);

        long[] t00 = T[ 0][x[ 0] & 0xFF];
        long[] t01 = T[ 1][x[ 1] & 0xFF];
        long[] t02 = T[ 2][x[ 2] & 0xFF];
        long[] t03 = T[ 3][x[ 3] & 0xFF];
        long[] t04 = T[ 4][x[ 4] & 0xFF];
        long[] t05 = T[ 5][x[ 5] & 0xFF];
        long[] t06 = T[ 6][x[ 6] & 0xFF];
        long[] t07 = T[ 7][x[ 7] & 0xFF];
        long[] t08 = T[ 8][x[ 8] & 0xFF];
        long[] t09 = T[ 9][x[ 9] & 0xFF];
        long[] t10 = T[10][x[10] & 0xFF];
        long[] t11 = T[11][x[11] & 0xFF];
        long[] t12 = T[12][x[12] & 0xFF];
        long[] t13 = T[13][x[13] & 0xFF];
        long[] t14 = T[14][x[14] & 0xFF];
        long[] t15 = T[15][x[15] & 0xFF];

        long z0 = t00[0] ^ t01[0] ^ t02[0] ^ t03[0] ^ t04[0] ^ t05[0] ^ t06[0] ^ t07[0]
                ^ t08[0] ^ t09[0] ^ t10[0] ^ t11[0] ^ t12[0] ^ t13[0] ^ t14[0] ^ t15[0];
        long z1 = t00[1] ^ t01[1] ^ t02[1] ^ t03[1] ^ t04[1] ^ t05[1] ^ t06[1] ^ t07[1]
                ^ t08[1] ^ t09[1] ^ t10[1] ^ t11[1] ^ t12[1] ^ t13[1] ^ t14[1] ^ t15[1];

        Pack.longToBigEndian(z0, x, 0);
        Pack.longToBigEndian(z1, x, 8);
    }
}