1 files changed, 40 insertions, 31 deletions

diff --git a/crypto/src/math/ec/multiplier/WTauNafMultiplier.cs b/crypto/src/math/ec/multiplier/WTauNafMultiplier.cs
index dda778eea..1e7ddae91 100644
--- a/crypto/src/math/ec/multiplier/WTauNafMultiplier.cs
+++ b/crypto/src/math/ec/multiplier/WTauNafMultiplier.cs
@@ -15,23 +15,23 @@ namespace Org.BouncyCastle.Math.EC.Multiplier
         internal static readonly string PRECOMP_NAME = "bc_wtnaf";
 
         /**
-        * Multiplies a {@link org.bouncycastle.math.ec.F2mPoint F2mPoint}
+        * Multiplies a {@link org.bouncycastle.math.ec.AbstractF2mPoint AbstractF2mPoint}
         * by <code>k</code> using the reduced <code>&#964;</code>-adic NAF (RTNAF)
         * method.
-        * @param p The F2mPoint to multiply.
+        * @param p The AbstractF2mPoint to multiply.
         * @param k The integer by which to multiply <code>k</code>.
         * @return <code>p</code> multiplied by <code>k</code>.
         */
         protected override ECPoint MultiplyPositive(ECPoint point, BigInteger k)
         {
-            if (!(point is F2mPoint))
-                throw new ArgumentException("Only F2mPoint can be used in WTauNafMultiplier");
-
-            F2mPoint p = (F2mPoint)point;
-            F2mCurve curve = (F2mCurve)p.Curve;
-            int m = curve.M;
-            sbyte a = (sbyte) curve.A.ToBigInteger().IntValue;
-            sbyte mu = curve.GetMu();
+            if (!(point is AbstractF2mPoint))
+                throw new ArgumentException("Only AbstractF2mPoint can be used in WTauNafMultiplier");
+
+            AbstractF2mPoint p = (AbstractF2mPoint)point;
+            AbstractF2mCurve curve = (AbstractF2mCurve)p.Curve;
+            int m = curve.FieldSize;
+            sbyte a = (sbyte)curve.A.ToBigInteger().IntValue;
+            sbyte mu = Tnaf.GetMu(a);
             BigInteger[] s = curve.GetSi();
 
             ZTauElement rho = Tnaf.PartModReduction(k, m, a, s, mu, (sbyte)10);
@@ -40,16 +40,16 @@ namespace Org.BouncyCastle.Math.EC.Multiplier
         }
 
         /**
-        * Multiplies a {@link org.bouncycastle.math.ec.F2mPoint F2mPoint}
+        * Multiplies a {@link org.bouncycastle.math.ec.AbstractF2mPoint AbstractF2mPoint}
         * by an element <code>&#955;</code> of <code><b>Z</b>[&#964;]</code> using
         * the <code>&#964;</code>-adic NAF (TNAF) method.
-        * @param p The F2mPoint to multiply.
+        * @param p The AbstractF2mPoint to multiply.
         * @param lambda The element <code>&#955;</code> of
         * <code><b>Z</b>[&#964;]</code> of which to compute the
         * <code>[&#964;]</code>-adic NAF.
         * @return <code>p</code> multiplied by <code>&#955;</code>.
         */
-        private F2mPoint MultiplyWTnaf(F2mPoint p, ZTauElement lambda,
+        private AbstractF2mPoint MultiplyWTnaf(AbstractF2mPoint p, ZTauElement lambda,
             PreCompInfo preCompInfo, sbyte a, sbyte mu)
         {
             ZTauElement[] alpha = (a == 0) ? Tnaf.Alpha0 : Tnaf.Alpha1;
@@ -63,20 +63,20 @@ namespace Org.BouncyCastle.Math.EC.Multiplier
         }
         
         /**
-        * Multiplies a {@link org.bouncycastle.math.ec.F2mPoint F2mPoint}
+        * Multiplies a {@link org.bouncycastle.math.ec.AbstractF2mPoint AbstractF2mPoint}
         * by an element <code>&#955;</code> of <code><b>Z</b>[&#964;]</code>
         * using the window <code>&#964;</code>-adic NAF (TNAF) method, given the
         * WTNAF of <code>&#955;</code>.
-        * @param p The F2mPoint to multiply.
+        * @param p The AbstractF2mPoint to multiply.
         * @param u The the WTNAF of <code>&#955;</code>..
         * @return <code>&#955; * p</code>
         */
-        private static F2mPoint MultiplyFromWTnaf(F2mPoint p, sbyte[] u, PreCompInfo preCompInfo)
+        private static AbstractF2mPoint MultiplyFromWTnaf(AbstractF2mPoint p, sbyte[] u, PreCompInfo preCompInfo)
         {
-            F2mCurve curve = (F2mCurve)p.Curve;
+            AbstractF2mCurve curve = (AbstractF2mCurve)p.Curve;
             sbyte a = (sbyte)curve.A.ToBigInteger().IntValue;
 
-            F2mPoint[] pu;
+            AbstractF2mPoint[] pu;
             if ((preCompInfo == null) || !(preCompInfo is WTauNafPreCompInfo))
             {
                 pu = Tnaf.GetPreComp(p, a);
@@ -90,26 +90,35 @@ namespace Org.BouncyCastle.Math.EC.Multiplier
                 pu = ((WTauNafPreCompInfo)preCompInfo).PreComp;
             }
 
+            // TODO Include negations in precomp (optionally) and use from here
+            AbstractF2mPoint[] puNeg = new AbstractF2mPoint[pu.Length];
+            for (int i = 0; i < pu.Length; ++i)
+            {
+                puNeg[i] = (AbstractF2mPoint)pu[i].Negate();
+            }
+
+            
             // q = infinity
-            F2mPoint q = (F2mPoint)curve.Infinity;
+            AbstractF2mPoint q = (AbstractF2mPoint) p.Curve.Infinity;
+
+            int tauCount = 0;
             for (int i = u.Length - 1; i >= 0; i--)
             {
-                q = Tnaf.Tau(q);
-                sbyte ui = u[i];
+                ++tauCount;
+                int ui = u[i];
                 if (ui != 0)
                 {
-                    if (ui > 0)
-                    {
-                        q = q.AddSimple(pu[ui]);
-                    }
-                    else
-                    {
-                        // u[i] < 0
-                        q = q.SubtractSimple(pu[-ui]);
-                    }
+                    q = q.TauPow(tauCount);
+                    tauCount = 0;
+
+                    ECPoint x = ui > 0 ? pu[ui >> 1] : puNeg[(-ui) >> 1];
+                    q = (AbstractF2mPoint)q.Add(x);
                 }
             }
-
+            if (tauCount > 0)
+            {
+                q = q.TauPow(tauCount);
+            }
             return q;
         }
     }