diff --git a/crypto/src/crypto/modes/gcm/GcmUtilities.cs b/crypto/src/crypto/modes/gcm/GcmUtilities.cs
index 1dd4cd612..ed88240f2 100644
--- a/crypto/src/crypto/modes/gcm/GcmUtilities.cs
+++ b/crypto/src/crypto/modes/gcm/GcmUtilities.cs
@@ -349,6 +349,14 @@ namespace Org.BouncyCastle.Crypto.Modes.Gcm
y[yOff + 1] = (x1 >> 8) | (x0 << 56);
}
+ internal static void MultiplyP16(ulong[] x)
+ {
+ ulong x0 = x[0], x1 = x[1];
+ ulong c = x1 << 48;
+ x[0] = (x0 >> 16) ^ c ^ (c >> 1) ^ (c >> 2) ^ (c >> 7);
+ x[1] = (x1 >> 16) | (x0 << 48);
+ }
+
internal static void Square(ulong[] x, ulong[] z)
{
ulong[] t = new ulong[4];
diff --git a/crypto/src/crypto/modes/gcm/Tables8kGcmMultiplier.cs b/crypto/src/crypto/modes/gcm/Tables8kGcmMultiplier.cs
index 81f60bb2f..8921c8621 100644
--- a/crypto/src/crypto/modes/gcm/Tables8kGcmMultiplier.cs
+++ b/crypto/src/crypto/modes/gcm/Tables8kGcmMultiplier.cs
@@ -15,7 +15,7 @@ namespace Org.BouncyCastle.Crypto.Modes.Gcm
{
if (T == null)
{
- T = new ulong[32][];
+ T = new ulong[2][];
}
else if (Arrays.AreEqual(this.H, H))
{
@@ -24,25 +24,25 @@ namespace Org.BouncyCastle.Crypto.Modes.Gcm
this.H = Arrays.Clone(H);
- for (int i = 0; i < 32; ++i)
+ for (int i = 0; i < 2; ++i)
{
- ulong[] t = T[i] = new ulong[32];
+ ulong[] t = T[i] = new ulong[512];
// t[0] = 0
if (i == 0)
{
- // t[1] = H.p^3
+ // t[1] = H.p^7
GcmUtilities.AsUlongs(this.H, t, 2);
- GcmUtilities.MultiplyP3(t, 2, t, 2);
+ GcmUtilities.MultiplyP7(t, 2, t, 2);
}
else
{
- // t[1] = T[i-1][1].p^4
- GcmUtilities.MultiplyP4(T[i - 1], 2, t, 2);
+ // t[1] = T[i-1][1].p^8
+ GcmUtilities.MultiplyP8(T[i - 1], 2, t, 2);
}
- for (int n = 2; n < 16; n += 2)
+ for (int n = 2; n < 256; n += 2)
{
// t[2.n] = t[n].p^-1
GcmUtilities.DivideP(t, n, t, n << 1);
@@ -55,23 +55,30 @@ namespace Org.BouncyCastle.Crypto.Modes.Gcm
public void MultiplyH(byte[] x)
{
+ ulong[] T0 = T[0], T1 = T[1];
+
//ulong[] z = new ulong[2];
- //for (int i = 15; i >= 0; --i)
+ //for (int i = 14; i >= 0; i -= 2)
//{
- // GcmUtilities.Xor(z, 0, T[i + i + 1], (x[i] & 0x0F) << 1);
- // GcmUtilities.Xor(z, 0, T[i + i], (x[i] & 0xF0) >> 3);
+ // GcmUtilities.MultiplyP16(z);
+ // GcmUtilities.Xor(z, 0, T0, x[i] << 1);
+ // GcmUtilities.Xor(z, 0, T1, x[i + 1] << 1);
//}
//Pack.UInt64_To_BE(z, x, 0);
- ulong z0 = 0, z1 = 0;
+ int vPos = x[15] << 1;
+ int uPos = x[14] << 1;
+ ulong z1 = T0[uPos + 1] ^ T1[vPos + 1];
+ ulong z0 = T0[uPos] ^ T1[vPos];
- for (int i = 15; i >= 0; --i)
+ for (int i = 12; i >= 0; i -= 2)
{
- ulong[] tu = T[i + i + 1], tv = T[i + i];
- int uPos = (x[i] & 0x0F) << 1, vPos = (x[i] & 0xF0) >> 3;
+ vPos = x[i + 1] << 1;
+ uPos = x[i] << 1;
- z0 ^= tu[uPos + 0] ^ tv[vPos + 0];
- z1 ^= tu[uPos + 1] ^ tv[vPos + 1];
+ ulong c = z1 << 48;
+ z1 = T0[uPos + 1] ^ T1[vPos + 1] ^ ((z1 >> 16) | (z0 << 48));
+ z0 = T0[uPos] ^ T1[vPos] ^ (z0 >> 16) ^ c ^ (c >> 1) ^ (c >> 2) ^ (c >> 7);
}
Pack.UInt64_To_BE(z0, x, 0);
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