- Initial commit

Runtime/3rdParty/BouncyCastle/math/ec/multiplier/FixedPointUtilities.cs

@@ -0,0 +1,99 @@
+#if !BESTHTTP_DISABLE_ALTERNATE_SSL && (!UNITY_WEBGL || UNITY_EDITOR)
+#pragma warning disable
+using System;
+
+namespace Best.HTTP.SecureProtocol.Org.BouncyCastle.Math.EC.Multiplier
+{
+    public class FixedPointUtilities
+    {
+        public static readonly string PRECOMP_NAME = "bc_fixed_point";
+
+        public static int GetCombSize(ECCurve c)
+        {
+            BigInteger order = c.Order;
+            return order == null ? c.FieldSize + 1 : order.BitLength;
+        }
+
+        public static FixedPointPreCompInfo GetFixedPointPreCompInfo(PreCompInfo preCompInfo)
+        {
+            return preCompInfo as FixedPointPreCompInfo;
+        }
+
+        public static FixedPointPreCompInfo Precompute(ECPoint p)
+        {
+            return (FixedPointPreCompInfo)p.Curve.Precompute(p, PRECOMP_NAME, new FixedPointCallback(p));
+        }
+
+        private class FixedPointCallback
+            : IPreCompCallback
+        {
+            private readonly ECPoint m_p;
+
+            internal FixedPointCallback(ECPoint p)
+            {
+                this.m_p = p;
+            }
+
+            public PreCompInfo Precompute(PreCompInfo existing)
+            {
+                FixedPointPreCompInfo existingFP = existing as FixedPointPreCompInfo;
+
+                ECCurve c = m_p.Curve;
+                int bits = FixedPointUtilities.GetCombSize(c);
+                int minWidth = bits > 250 ? 6 : 5;
+                int n = 1 << minWidth;
+
+                if (CheckExisting(existingFP, n))
+                    return existingFP;
+
+                int d = (bits + minWidth - 1) / minWidth;
+
+                ECPoint[] pow2Table = new ECPoint[minWidth + 1];
+                pow2Table[0] = m_p;
+                for (int i = 1; i < minWidth; ++i)
+                {
+                    pow2Table[i] = pow2Table[i - 1].TimesPow2(d);
+                }
+
+                // This will be the 'offset' value 
+                pow2Table[minWidth] = pow2Table[0].Subtract(pow2Table[1]);
+
+                c.NormalizeAll(pow2Table);
+
+                ECPoint[] lookupTable = new ECPoint[n];
+                lookupTable[0] = pow2Table[0];
+
+                for (int bit = minWidth - 1; bit >= 0; --bit)
+                {
+                    ECPoint pow2 = pow2Table[bit];
+
+                    int step = 1 << bit;
+                    for (int i = step; i < n; i += (step << 1))
+                    {
+                        lookupTable[i] = lookupTable[i - step].Add(pow2);
+                    }
+                }
+
+                c.NormalizeAll(lookupTable);
+
+                FixedPointPreCompInfo result = new FixedPointPreCompInfo();
+                result.LookupTable = c.CreateCacheSafeLookupTable(lookupTable, 0, lookupTable.Length);
+                result.Offset = pow2Table[minWidth];
+                result.Width = minWidth;
+                return result;
+            }
+
+            private bool CheckExisting(FixedPointPreCompInfo existingFP, int n)
+            {
+                return existingFP != null && CheckTable(existingFP.LookupTable, n);
+            }
+
+            private bool CheckTable(ECLookupTable table, int n)
+            {
+                return table != null && table.Size >= n;
+            }
+        }
+    }
+}
+#pragma warning restore
+#endif