1 files changed, 70 insertions, 0 deletions
diff --git a/crypto/src/crypto/modes/gcm/Tables4kGcmMultiplier.cs b/crypto/src/crypto/modes/gcm/Tables4kGcmMultiplier.cs
new file mode 100644
index 000000000..3ed596e94
--- /dev/null
+++ b/crypto/src/crypto/modes/gcm/Tables4kGcmMultiplier.cs
@@ -0,0 +1,70 @@
+using System;
+
+using Org.BouncyCastle.Crypto.Utilities;
+using Org.BouncyCastle.Utilities;
+
+namespace Org.BouncyCastle.Crypto.Modes.Gcm
+{
+    public class Tables4kGcmMultiplier
+        : IGcmMultiplier
+    {
+        private byte[] H;
+        private ulong[] T;
+
+        public void Init(byte[] H)
+        {
+            if (T == null)
+            {
+                T = new ulong[512];
+            }
+            else if (Arrays.AreEqual(this.H, H))
+            {
+                return;
+            }
+
+            this.H = Arrays.Clone(H);
+
+            // T[0] = 0
+
+            // T[1] = H.p^7
+            GcmUtilities.AsUlongs(this.H, T, 2);
+            GcmUtilities.MultiplyP7(T, 2, T, 2);
+
+            for (int n = 2; n < 256; n += 2)
+            {
+                // T[2.n] = T[n].p^-1
+                GcmUtilities.DivideP(T, n, T, n << 1);
+
+                // T[2.n + 1] = T[2.n] + T[1]
+                GcmUtilities.Xor(T, n << 1, T, 2, T, (n + 1) << 1);
+            }
+        }
+
+        public void MultiplyH(byte[] x)
+        {
+            //ulong[] z = new ulong[2];
+            //GcmUtilities.Copy(T, x[15] << 1, z, 0);
+            //for (int i = 14; i >= 0; --i)
+            //{
+            //    GcmUtilities.MultiplyP8(z);
+            //    GcmUtilities.Xor(z, 0, T, x[i] << 1);
+            //}
+            //Pack.UInt64_To_BE(z, x, 0);
+
+            int pos = x[15] << 1;
+            ulong z0 = T[pos + 0], z1 = T[pos + 1];
+
+            for (int i = 14; i >= 0; --i)
+            {
+                pos = x[i] << 1;
+
+                ulong c = z1 << 56;
+                z1 = T[pos + 1] ^ ((z1 >> 8) | (z0 << 56));
+                z0 = T[pos + 0] ^ (z0 >> 8) ^ c ^ (c >> 1) ^ (c >> 2) ^ (c >> 7);
+            }
+
+            Pack.UInt64_To_BE(z0, x, 0);
+            Pack.UInt64_To_BE(z1, x, 8);
+        }
+    }
+}