Tables8kGCMMultiplier.java revision e1142c149e244797ce73b0e7fad40816e447a817 
1package org.bouncycastle.crypto.modes.gcm;
2
3import org.bouncycastle.crypto.util.Pack;
4import org.bouncycastle.util.Arrays;
5
6public class Tables8kGCMMultiplier  implements GCMMultiplier
7{
8    private byte[] H;
9    private int[][][] M;
10
11    public void init(byte[] H)
12    {
13        if (M == null)
14        {
15            M = new int[32][16][4];
16        }
17        else if (Arrays.areEqual(this.H, H))
18        {
19            return;
20        }
21
22        this.H = Arrays.clone(H);
23
24        // M[0][0] is ZEROES;
25        // M[1][0] is ZEROES;
26        GCMUtil.asInts(H, M[1][8]);
27
28        for (int j = 4; j >= 1; j >>= 1)
29        {
30            GCMUtil.multiplyP(M[1][j + j], M[1][j]);
31        }
32
33        GCMUtil.multiplyP(M[1][1], M[0][8]);
34
35        for (int j = 4; j >= 1; j >>= 1)
36        {
37            GCMUtil.multiplyP(M[0][j + j], M[0][j]);
38        }
39
40        int i = 0;
41        for (;;)
42        {
43            for (int j = 2; j < 16; j += j)
44            {
45                for (int k = 1; k < j; ++k)
46                {
47                    GCMUtil.xor(M[i][j], M[i][k], M[i][j + k]);
48                }
49            }
50
51            if (++i == 32)
52            {
53                return;
54            }
55
56            if (i > 1)
57            {
58                // M[i][0] is ZEROES;
59                for(int j = 8; j > 0; j >>= 1)
60                {
61                    GCMUtil.multiplyP8(M[i - 2][j], M[i][j]);
62                }
63            }
64        }
65    }
66
67    public void multiplyH(byte[] x)
68    {
69//      assert x.Length == 16;
70
71        int[] z = new int[4];
72        for (int i = 15; i >= 0; --i)
73        {
74//            GCMUtil.xor(z, M[i + i][x[i] & 0x0f]);
75            int[] m = M[i + i][x[i] & 0x0f];
76            z[0] ^= m[0];
77            z[1] ^= m[1];
78            z[2] ^= m[2];
79            z[3] ^= m[3];
80//            GCMUtil.xor(z, M[i + i + 1][(x[i] & 0xf0) >>> 4]);
81            m = M[i + i + 1][(x[i] & 0xf0) >>> 4];
82            z[0] ^= m[0];
83            z[1] ^= m[1];
84            z[2] ^= m[2];
85            z[3] ^= m[3];
86        }
87
88        Pack.intToBigEndian(z, x, 0);
89    }
90}