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-rw-r--r--crypto/src/math/ec/ECAlgorithms.cs31
-rw-r--r--crypto/src/math/ec/ECCurve.cs73
-rw-r--r--crypto/src/math/ec/ECFieldElement.cs94
-rw-r--r--crypto/src/math/ec/ECPoint.cs170
-rw-r--r--crypto/src/math/ec/custom/djb/Curve25519FieldElement.cs2
-rw-r--r--crypto/src/math/ec/custom/gm/SM2P256V1FieldElement.cs2
-rw-r--r--crypto/src/math/ec/custom/sec/SecP128R1FieldElement.cs2
-rw-r--r--crypto/src/math/ec/custom/sec/SecP160R1FieldElement.cs2
-rw-r--r--crypto/src/math/ec/custom/sec/SecP160R2FieldElement.cs2
-rw-r--r--crypto/src/math/ec/custom/sec/SecP192K1FieldElement.cs2
-rw-r--r--crypto/src/math/ec/custom/sec/SecP192R1FieldElement.cs2
-rw-r--r--crypto/src/math/ec/custom/sec/SecP224K1FieldElement.cs2
-rw-r--r--crypto/src/math/ec/custom/sec/SecP224R1FieldElement.cs2
-rw-r--r--crypto/src/math/ec/custom/sec/SecP256K1FieldElement.cs2
-rw-r--r--crypto/src/math/ec/custom/sec/SecP256R1FieldElement.cs2
-rw-r--r--crypto/src/math/ec/custom/sec/SecP384R1FieldElement.cs2
-rw-r--r--crypto/src/math/ec/custom/sec/SecP521R1FieldElement.cs2
-rw-r--r--crypto/src/math/ec/custom/sec/SecT113FieldElement.cs7
-rw-r--r--crypto/src/math/ec/custom/sec/SecT131FieldElement.cs7
-rw-r--r--crypto/src/math/ec/custom/sec/SecT163FieldElement.cs7
-rw-r--r--crypto/src/math/ec/custom/sec/SecT193FieldElement.cs7
-rw-r--r--crypto/src/math/ec/custom/sec/SecT233FieldElement.cs7
-rw-r--r--crypto/src/math/ec/custom/sec/SecT239FieldElement.cs7
-rw-r--r--crypto/src/math/ec/custom/sec/SecT283FieldElement.cs7
-rw-r--r--crypto/src/math/ec/custom/sec/SecT409FieldElement.cs7
-rw-r--r--crypto/src/math/ec/custom/sec/SecT571FieldElement.cs7
-rw-r--r--crypto/src/math/ec/multiplier/AbstractECMultiplier.cs7
-rw-r--r--crypto/src/math/ec/multiplier/FixedPointCombMultiplier.cs6
-rw-r--r--crypto/src/math/ec/multiplier/FixedPointPreCompInfo.cs14
-rw-r--r--crypto/src/math/ec/multiplier/FixedPointUtilities.cs63
-rw-r--r--crypto/src/math/ec/multiplier/IPreCompCallback.cs9
-rw-r--r--crypto/src/math/ec/multiplier/ValidityPreCompInfo.cs44
-rw-r--r--crypto/src/math/ec/multiplier/WNafUtilities.cs311
-rw-r--r--crypto/src/math/ec/multiplier/WTauNafMultiplier.cs47
34 files changed, 630 insertions, 328 deletions
diff --git a/crypto/src/math/ec/ECAlgorithms.cs b/crypto/src/math/ec/ECAlgorithms.cs
index 5d60de40f..b05c0201a 100644
--- a/crypto/src/math/ec/ECAlgorithms.cs
+++ b/crypto/src/math/ec/ECAlgorithms.cs
@@ -58,10 +58,10 @@ namespace Org.BouncyCastle.Math.EC
             GlvEndomorphism glvEndomorphism = c.GetEndomorphism() as GlvEndomorphism;
             if (glvEndomorphism != null)
             {
-                return ValidatePoint(ImplSumOfMultipliesGlv(imported, ks, glvEndomorphism));
+                return ImplCheckResult(ImplSumOfMultipliesGlv(imported, ks, glvEndomorphism));
             }
 
-            return ValidatePoint(ImplSumOfMultiplies(imported, ks));
+            return ImplCheckResult(ImplSumOfMultiplies(imported, ks));
         }
 
         public static ECPoint SumOfTwoMultiplies(ECPoint P, BigInteger a, ECPoint Q, BigInteger b)
@@ -74,18 +74,18 @@ namespace Org.BouncyCastle.Math.EC
                 AbstractF2mCurve f2mCurve = cp as AbstractF2mCurve;
                 if (f2mCurve != null && f2mCurve.IsKoblitz)
                 {
-                    return ValidatePoint(P.Multiply(a).Add(Q.Multiply(b)));
+                    return ImplCheckResult(P.Multiply(a).Add(Q.Multiply(b)));
                 }
             }
 
             GlvEndomorphism glvEndomorphism = cp.GetEndomorphism() as GlvEndomorphism;
             if (glvEndomorphism != null)
             {
-                return ValidatePoint(
+                return ImplCheckResult(
                     ImplSumOfMultipliesGlv(new ECPoint[] { P, Q }, new BigInteger[] { a, b }, glvEndomorphism));
             }
 
-            return ValidatePoint(ImplShamirsTrickWNaf(P, a, Q, b));
+            return ImplCheckResult(ImplShamirsTrickWNaf(P, a, Q, b));
         }
 
         /*
@@ -111,7 +111,7 @@ namespace Org.BouncyCastle.Math.EC
             ECCurve cp = P.Curve;
             Q = ImportPoint(cp, Q);
 
-            return ValidatePoint(ImplShamirsTrickJsf(P, k, Q, l));
+            return ImplCheckResult(ImplShamirsTrickJsf(P, k, Q, l));
         }
 
         public static ECPoint ImportPoint(ECCurve c, ECPoint p)
@@ -202,7 +202,24 @@ namespace Org.BouncyCastle.Math.EC
         public static ECPoint ValidatePoint(ECPoint p)
         {
             if (!p.IsValid())
-                throw new ArgumentException("Invalid point", "p");
+                throw new InvalidOperationException("Invalid point");
+
+            return p;
+        }
+
+        public static ECPoint CleanPoint(ECCurve c, ECPoint p)
+        {
+            ECCurve cp = p.Curve;
+            if (!c.Equals(cp))
+                throw new ArgumentException("Point must be on the same curve", "p");
+
+            return c.DecodePoint(p.GetEncoded(false));
+        }
+
+        internal static ECPoint ImplCheckResult(ECPoint p)
+        {
+            if (!p.IsValidPartial())
+                throw new InvalidOperationException("Invalid result");
 
             return p;
         }
diff --git a/crypto/src/math/ec/ECCurve.cs b/crypto/src/math/ec/ECCurve.cs
index 6a9342722..993b69149 100644
--- a/crypto/src/math/ec/ECCurve.cs
+++ b/crypto/src/math/ec/ECCurve.cs
@@ -161,15 +161,24 @@ namespace Org.BouncyCastle.Math.EC
         public virtual PreCompInfo GetPreCompInfo(ECPoint point, string name)
         {
             CheckPoint(point);
+
+            IDictionary table;
             lock (point)
             {
-                IDictionary table = point.m_preCompTable;
-                return table == null ? null : (PreCompInfo)table[name];
+                table = point.m_preCompTable;
+            }
+
+            if (null == table)
+                return null;
+
+            lock (table)
+            {
+                return (PreCompInfo)table[name];
             }
         }
 
         /**
-         * Adds <code>PreCompInfo</code> for a point on this curve, under a given name. Used by
+         * Compute a <code>PreCompInfo</code> for a point on this curve, under a given name. Used by
          * <code>ECMultiplier</code>s to save the precomputation for this <code>ECPoint</code> for use
          * by subsequent multiplication.
          * 
@@ -177,20 +186,34 @@ namespace Org.BouncyCastle.Math.EC
          *            The <code>ECPoint</code> to store precomputations for.
          * @param name
          *            A <code>String</code> used to index precomputations of different types.
-         * @param preCompInfo
-         *            The values precomputed by the <code>ECMultiplier</code>.
+         * @param callback
+         *            Called to calculate the <code>PreCompInfo</code>.
          */
-        public virtual void SetPreCompInfo(ECPoint point, string name, PreCompInfo preCompInfo)
+        public virtual PreCompInfo Precompute(ECPoint point, string name, IPreCompCallback callback)
         {
             CheckPoint(point);
+
+            IDictionary table;
             lock (point)
             {
-                IDictionary table = point.m_preCompTable;
+                table = point.m_preCompTable;
                 if (null == table)
                 {
                     point.m_preCompTable = table = Platform.CreateHashtable(4);
                 }
-                table[name] = preCompInfo;
+            }
+
+            lock (table)
+            {
+                PreCompInfo existing = (PreCompInfo)table[name];
+                PreCompInfo result = callback.Precompute(existing);
+
+                if (result != existing)
+                {
+                    table[name] = result;
+                }
+
+                return result;
             }
         }
 
@@ -208,7 +231,7 @@ namespace Org.BouncyCastle.Math.EC
             // TODO Default behaviour could be improved if the two curves have the same coordinate system by copying any Z coordinates.
             p = p.Normalize();
 
-            return ValidatePoint(p.XCoord.ToBigInteger(), p.YCoord.ToBigInteger(), p.IsCompressed);
+            return CreatePoint(p.XCoord.ToBigInteger(), p.YCoord.ToBigInteger(), p.IsCompressed);
         }
 
         /**
@@ -453,7 +476,7 @@ namespace Org.BouncyCastle.Math.EC
                     BigInteger X = new BigInteger(1, encoded, 1, expectedLength);
 
                     p = DecompressPoint(yTilde, X);
-                    if (!p.SatisfiesCofactor())
+                    if (!p.ImplIsValid(true, true))
                         throw new ArgumentException("Invalid point");
 
                     break;
@@ -588,6 +611,7 @@ namespace Org.BouncyCastle.Math.EC
         protected readonly BigInteger m_q, m_r;
         protected readonly FpPoint m_infinity;
 
+        [Obsolete("Use constructor taking order/cofactor")]
         public FpCurve(BigInteger q, BigInteger a, BigInteger b)
             : this(q, a, b, null, null)
         {
@@ -598,7 +622,7 @@ namespace Org.BouncyCastle.Math.EC
         {
             this.m_q = q;
             this.m_r = FpFieldElement.CalculateResidue(q);
-            this.m_infinity = new FpPoint(this, null, null);
+            this.m_infinity = new FpPoint(this, null, null, false);
 
             this.m_a = FromBigInteger(a);
             this.m_b = FromBigInteger(b);
@@ -607,6 +631,7 @@ namespace Org.BouncyCastle.Math.EC
             this.m_coord = FP_DEFAULT_COORDS;
         }
 
+        [Obsolete("Use constructor taking order/cofactor")]
         protected FpCurve(BigInteger q, BigInteger r, ECFieldElement a, ECFieldElement b)
             : this(q, r, a, b, null, null)
         {
@@ -617,7 +642,7 @@ namespace Org.BouncyCastle.Math.EC
         {
             this.m_q = q;
             this.m_r = r;
-            this.m_infinity = new FpPoint(this, null, null);
+            this.m_infinity = new FpPoint(this, null, null, false);
 
             this.m_a = a;
             this.m_b = b;
@@ -794,7 +819,7 @@ namespace Org.BouncyCastle.Math.EC
             else
             {
                 ECFieldElement beta = xp.Square().Invert().Multiply(B).Add(A).Add(xp);
-                ECFieldElement z = SolveQuadradicEquation(beta);
+                ECFieldElement z = SolveQuadraticEquation(beta);
 
                 if (z != null)
                 {
@@ -831,11 +856,11 @@ namespace Org.BouncyCastle.Math.EC
          * D.1.6) The other solution is <code>z + 1</code>.
          *
          * @param beta
-         *            The value to solve the qradratic equation for.
+         *            The value to solve the quadratic equation for.
          * @return the solution for <code>z<sup>2</sup> + z = beta</code> or
          *         <code>null</code> if no solution exists.
          */
-        private ECFieldElement SolveQuadradicEquation(ECFieldElement beta)
+        internal ECFieldElement SolveQuadraticEquation(ECFieldElement beta)
         {
             if (beta.IsZero)
                 return beta;
@@ -957,6 +982,7 @@ namespace Org.BouncyCastle.Math.EC
          * for non-supersingular elliptic curves over
          * <code>F<sub>2<sup>m</sup></sub></code>.
          */
+        [Obsolete("Use constructor taking order/cofactor")]
         public F2mCurve(
             int			m,
             int			k,
@@ -1014,6 +1040,7 @@ namespace Org.BouncyCastle.Math.EC
          * for non-supersingular elliptic curves over
          * <code>F<sub>2<sup>m</sup></sub></code>.
          */
+        [Obsolete("Use constructor taking order/cofactor")]
         public F2mCurve(
             int			m,
             int			k1,
@@ -1065,7 +1092,7 @@ namespace Org.BouncyCastle.Math.EC
             this.k3 = k3;
             this.m_order = order;
             this.m_cofactor = cofactor;
-            this.m_infinity = new F2mPoint(this, null, null);
+            this.m_infinity = new F2mPoint(this, null, null, false);
 
             if (k1 == 0)
                 throw new ArgumentException("k1 must be > 0");
@@ -1099,7 +1126,7 @@ namespace Org.BouncyCastle.Math.EC
             this.m_order = order;
             this.m_cofactor = cofactor;
 
-            this.m_infinity = new F2mPoint(this, null, null);
+            this.m_infinity = new F2mPoint(this, null, null, false);
             this.m_a = a;
             this.m_b = b;
             this.m_coord = F2M_DEFAULT_COORDS;
@@ -1188,18 +1215,6 @@ namespace Org.BouncyCastle.Math.EC
             get { return k3; }
         }
 
-        [Obsolete("Use 'Order' property instead")]
-        public BigInteger N
-        {
-            get { return m_order; }
-        }
-
-        [Obsolete("Use 'Cofactor' property instead")]
-        public BigInteger H
-        {
-            get { return m_cofactor; }
-        }
-
         public override ECLookupTable CreateCacheSafeLookupTable(ECPoint[] points, int off, int len)
         {
             int FE_LONGS = (m + 63) / 64;
diff --git a/crypto/src/math/ec/ECFieldElement.cs b/crypto/src/math/ec/ECFieldElement.cs
index 3676c81b1..350e8c6d4 100644
--- a/crypto/src/math/ec/ECFieldElement.cs
+++ b/crypto/src/math/ec/ECFieldElement.cs
@@ -101,9 +101,14 @@ namespace Org.BouncyCastle.Math.EC
         }
     }
 
-    public class FpFieldElement
+    public abstract class AbstractFpFieldElement
         : ECFieldElement
     {
+    }
+
+    public class FpFieldElement
+        : AbstractFpFieldElement
+    {
         private readonly BigInteger q, r, x;
 
         internal static BigInteger CalculateResidue(BigInteger p)
@@ -536,6 +541,45 @@ namespace Org.BouncyCastle.Math.EC
         }
     }
 
+    public abstract class AbstractF2mFieldElement
+        :   ECFieldElement
+    {
+        public virtual ECFieldElement HalfTrace()
+        {
+            int m = FieldSize;
+            if ((m & 1) == 0)
+                throw new InvalidOperationException("Half-trace only defined for odd m");
+
+            ECFieldElement fe = this;
+            ECFieldElement ht = fe;
+            for (int i = 2; i < m; i += 2)
+            {
+                fe = fe.SquarePow(2);
+                ht = ht.Add(fe);
+            }
+
+            return ht;
+        }
+
+        public virtual int Trace()
+        {
+            int m = FieldSize;
+            ECFieldElement fe = this;
+            ECFieldElement tr = fe;
+            for (int i = 1; i < m; ++i)
+            {
+                fe = fe.Square();
+                tr = tr.Add(fe);
+            }
+            if (tr.IsZero)
+                return 0;
+            if (tr.IsOne)
+                return 1;
+
+            throw new InvalidOperationException("Internal error in trace calculation");
+        }
+    }
+
     /**
      * Class representing the Elements of the finite field
      * <code>F<sub>2<sup>m</sup></sub></code> in polynomial basis (PB)
@@ -544,7 +588,7 @@ namespace Org.BouncyCastle.Math.EC
      * representation is not supported.
      */
     public class F2mFieldElement
-        : ECFieldElement
+        :   AbstractF2mFieldElement
     {
         /**
          * Indicates gaussian normal basis representation (GNB). Number chosen
@@ -582,20 +626,21 @@ namespace Org.BouncyCastle.Math.EC
         internal LongArray x;
 
         /**
-            * Constructor for Ppb.
-            * @param m  The exponent <code>m</code> of
-            * <code>F<sub>2<sup>m</sup></sub></code>.
-            * @param k1 The integer <code>k1</code> where <code>x<sup>m</sup> +
-            * x<sup>k3</sup> + x<sup>k2</sup> + x<sup>k1</sup> + 1</code>
-            * represents the reduction polynomial <code>f(z)</code>.
-            * @param k2 The integer <code>k2</code> where <code>x<sup>m</sup> +
-            * x<sup>k3</sup> + x<sup>k2</sup> + x<sup>k1</sup> + 1</code>
-            * represents the reduction polynomial <code>f(z)</code>.
-            * @param k3 The integer <code>k3</code> where <code>x<sup>m</sup> +
-            * x<sup>k3</sup> + x<sup>k2</sup> + x<sup>k1</sup> + 1</code>
-            * represents the reduction polynomial <code>f(z)</code>.
-            * @param x The BigInteger representing the value of the field element.
-            */
+         * Constructor for Ppb.
+         * @param m  The exponent <code>m</code> of
+         * <code>F<sub>2<sup>m</sup></sub></code>.
+         * @param k1 The integer <code>k1</code> where <code>x<sup>m</sup> +
+         * x<sup>k3</sup> + x<sup>k2</sup> + x<sup>k1</sup> + 1</code>
+         * represents the reduction polynomial <code>f(z)</code>.
+         * @param k2 The integer <code>k2</code> where <code>x<sup>m</sup> +
+         * x<sup>k3</sup> + x<sup>k2</sup> + x<sup>k1</sup> + 1</code>
+         * represents the reduction polynomial <code>f(z)</code>.
+         * @param k3 The integer <code>k3</code> where <code>x<sup>m</sup> +
+         * x<sup>k3</sup> + x<sup>k2</sup> + x<sup>k1</sup> + 1</code>
+         * represents the reduction polynomial <code>f(z)</code>.
+         * @param x The BigInteger representing the value of the field element.
+         */
+        [Obsolete("Use ECCurve.FromBigInteger to construct field elements")]
         public F2mFieldElement(
             int			m,
             int			k1,
@@ -627,14 +672,15 @@ namespace Org.BouncyCastle.Math.EC
         }
 
         /**
-            * Constructor for Tpb.
-            * @param m  The exponent <code>m</code> of
-            * <code>F<sub>2<sup>m</sup></sub></code>.
-            * @param k The integer <code>k</code> where <code>x<sup>m</sup> +
-            * x<sup>k</sup> + 1</code> represents the reduction
-            * polynomial <code>f(z)</code>.
-            * @param x The BigInteger representing the value of the field element.
-            */
+         * Constructor for Tpb.
+         * @param m  The exponent <code>m</code> of
+         * <code>F<sub>2<sup>m</sup></sub></code>.
+         * @param k The integer <code>k</code> where <code>x<sup>m</sup> +
+         * x<sup>k</sup> + 1</code> represents the reduction
+         * polynomial <code>f(z)</code>.
+         * @param x The BigInteger representing the value of the field element.
+         */
+        [Obsolete("Use ECCurve.FromBigInteger to construct field elements")]
         public F2mFieldElement(
             int			m,
             int			k,
diff --git a/crypto/src/math/ec/ECPoint.cs b/crypto/src/math/ec/ECPoint.cs
index a5ba515c5..2acc9f5c0 100644
--- a/crypto/src/math/ec/ECPoint.cs
+++ b/crypto/src/math/ec/ECPoint.cs
@@ -67,13 +67,19 @@ namespace Org.BouncyCastle.Math.EC
             this.m_withCompression = withCompression;
         }
 
-        protected internal bool SatisfiesCofactor()
+        protected abstract bool SatisfiesCurveEquation();
+
+        protected virtual bool SatisfiesOrder()
         {
-            BigInteger h = Curve.Cofactor;
-            return h == null || h.Equals(BigInteger.One) || !ECAlgorithms.ReferenceMultiply(this, h).IsInfinity;
-        }
+            if (BigInteger.One.Equals(Curve.Cofactor))
+                return true;
 
-        protected abstract bool SatisfiesCurveEquation();
+            BigInteger n = Curve.Order;
+
+            // TODO Require order to be available for all curves
+
+            return n == null || ECAlgorithms.ReferenceMultiply(this, n).IsInfinity;
+        }
 
         public ECPoint GetDetachedPoint()
         {
@@ -97,30 +103,6 @@ namespace Org.BouncyCastle.Math.EC
         }
 
         /**
-         * Normalizes this point, and then returns the affine x-coordinate.
-         * 
-         * Note: normalization can be expensive, this method is deprecated in favour
-         * of caller-controlled normalization.
-         */
-        [Obsolete("Use AffineXCoord, or Normalize() and XCoord, instead")]
-        public virtual ECFieldElement X
-        {
-            get { return Normalize().XCoord; }
-        }
-
-        /**
-         * Normalizes this point, and then returns the affine y-coordinate.
-         * 
-         * Note: normalization can be expensive, this method is deprecated in favour
-         * of caller-controlled normalization.
-         */
-        [Obsolete("Use AffineYCoord, or Normalize() and YCoord, instead")]
-        public virtual ECFieldElement Y
-        {
-            get { return Normalize().YCoord; }
-        }
-
-        /**
          * Returns the affine x-coordinate after checking that this point is normalized.
          * 
          * @return The affine x-coordinate of this point
@@ -299,22 +281,22 @@ namespace Org.BouncyCastle.Math.EC
 
         public bool IsValid()
         {
-            if (IsInfinity)
-                return true;
-
-            // TODO Sanity-check the field elements
+            return ImplIsValid(false, true);
+        }
 
-            ECCurve curve = Curve;
-            if (curve != null)
-            {
-                if (!SatisfiesCurveEquation())
-                    return false;
+        internal bool IsValidPartial()
+        {
+            return ImplIsValid(false, false);
+        }
 
-                if (!SatisfiesCofactor())
-                    return false;
-            }
+        internal bool ImplIsValid(bool decompressed, bool checkOrder)
+        {
+            if (IsInfinity)
+                return true;
 
-            return true;
+            ValidityCallback callback = new ValidityCallback(this, decompressed, checkOrder);
+            ValidityPreCompInfo validity = (ValidityPreCompInfo)Curve.Precompute(this, ValidityPreCompInfo.PRECOMP_NAME, callback);
+            return !validity.HasFailed();
         }
 
         public virtual ECPoint ScaleX(ECFieldElement scale)
@@ -462,6 +444,52 @@ namespace Org.BouncyCastle.Math.EC
         {
             return TwicePlus(this);
         }
+
+        private class ValidityCallback
+            : IPreCompCallback
+        {
+            private readonly ECPoint m_outer;
+            private readonly bool m_decompressed, m_checkOrder;
+
+            internal ValidityCallback(ECPoint outer, bool decompressed, bool checkOrder)
+            {
+                this.m_outer = outer;
+                this.m_decompressed = decompressed;
+                this.m_checkOrder = checkOrder;
+            }
+
+            public PreCompInfo Precompute(PreCompInfo existing)
+            {
+                ValidityPreCompInfo info = existing as ValidityPreCompInfo;
+                if (info == null)
+                {
+                    info = new ValidityPreCompInfo();
+                }
+
+                if (info.HasFailed())
+                    return info;
+
+                if (!info.HasCurveEquationPassed())
+                {
+                    if (!m_decompressed && !m_outer.SatisfiesCurveEquation())
+                    {
+                        info.ReportFailed();
+                        return info;
+                    }
+                    info.ReportCurveEquationPassed();
+                }
+                if (m_checkOrder && !info.HasOrderPassed())
+                {
+                    if (!m_outer.SatisfiesOrder())
+                    {
+                        info.ReportFailed();
+                        return info;
+                    }
+                    info.ReportOrderPassed();
+                }
+                return info;
+            }
+        }
     }
 
     public abstract class ECPointBase
@@ -608,6 +636,7 @@ namespace Org.BouncyCastle.Math.EC
          * @param x affine x co-ordinate
          * @param y affine y co-ordinate
          */
+        [Obsolete("Use ECCurve.CreatePoint to construct points")]
         public FpPoint(ECCurve curve, ECFieldElement x, ECFieldElement y)
             : this(curve, x, y, false)
         {
@@ -621,6 +650,7 @@ namespace Org.BouncyCastle.Math.EC
          * @param y affine y co-ordinate
          * @param withCompression if true encode with point compression
          */
+        [Obsolete("Per-point compression property will be removed, see GetEncoded(bool)")]
         public FpPoint(ECCurve curve, ECFieldElement x, ECFieldElement y, bool withCompression)
             : base(curve, x, y, withCompression)
         {
@@ -635,7 +665,7 @@ namespace Org.BouncyCastle.Math.EC
 
         protected override ECPoint Detach()
         {
-            return new FpPoint(null, AffineXCoord, AffineYCoord);
+            return new FpPoint(null, AffineXCoord, AffineYCoord, false);
         }
 
         public override ECFieldElement GetZCoord(int index)
@@ -1384,6 +1414,46 @@ namespace Org.BouncyCastle.Math.EC
             return lhs.Equals(rhs);
         }
 
+        protected override bool SatisfiesOrder()
+        {
+            ECCurve curve = Curve;
+            BigInteger cofactor = curve.Cofactor;
+            if (BigInteger.Two.Equals(cofactor))
+            {
+                /*
+                 *  Check that the trace of (X + A) is 0, then there exists a solution to L^2 + L = X + A,
+                 *  and so a halving is possible, so this point is the double of another.  
+                 */
+                ECPoint N = this.Normalize();
+                ECFieldElement X = N.AffineXCoord;
+                ECFieldElement rhs = X.Add(curve.A);
+                return ((AbstractF2mFieldElement)rhs).Trace() == 0;
+            }
+            if (BigInteger.ValueOf(4).Equals(cofactor))
+            {
+                /*
+                 * Solve L^2 + L = X + A to find the half of this point, if it exists (fail if not).
+                 * Generate both possibilities for the square of the half-point's x-coordinate (w),
+                 * and check if Tr(w + A) == 0 for at least one; then a second halving is possible
+                 * (see comments for cofactor 2 above), so this point is four times another.
+                 * 
+                 * Note: Tr(x^2) == Tr(x). 
+                 */
+                ECPoint N = this.Normalize();
+                ECFieldElement X = N.AffineXCoord;
+                ECFieldElement lambda = ((AbstractF2mCurve)curve).SolveQuadraticEquation(X.Add(curve.A));
+                if (lambda == null)
+                    return false;
+
+                ECFieldElement w = X.Multiply(lambda).Add(N.AffineYCoord);
+                ECFieldElement t = w.Add(curve.A);
+                return ((AbstractF2mFieldElement)t).Trace() == 0
+                    || ((AbstractF2mFieldElement)(t.Add(X))).Trace() == 0;
+            }
+
+            return base.SatisfiesOrder();
+        }
+
         public override ECPoint ScaleX(ECFieldElement scale)
         {
             if (this.IsInfinity)
@@ -1529,6 +1599,7 @@ namespace Org.BouncyCastle.Math.EC
          * @param x x point
          * @param y y point
          */
+        [Obsolete("Use ECCurve.CreatePoint to construct points")]
         public F2mPoint(
             ECCurve			curve,
             ECFieldElement	x,
@@ -1543,6 +1614,7 @@ namespace Org.BouncyCastle.Math.EC
          * @param y y point
          * @param withCompression true if encode with point compression.
          */
+        [Obsolete("Per-point compression property will be removed, see GetEncoded(bool)")]
         public F2mPoint(
             ECCurve			curve,
             ECFieldElement	x,
@@ -1573,19 +1645,9 @@ namespace Org.BouncyCastle.Math.EC
         {
         }
 
-        /**
-         * Constructor for point at infinity
-         */
-        [Obsolete("Use ECCurve.Infinity property")]
-        public F2mPoint(
-            ECCurve curve)
-            : this(curve, null, null)
-        {
-        }
-
         protected override ECPoint Detach()
         {
-            return new F2mPoint(null, AffineXCoord, AffineYCoord);
+            return new F2mPoint(null, AffineXCoord, AffineYCoord, false);
         }
 
         public override ECFieldElement YCoord
diff --git a/crypto/src/math/ec/custom/djb/Curve25519FieldElement.cs b/crypto/src/math/ec/custom/djb/Curve25519FieldElement.cs
index 732e9e468..37256a550 100644
--- a/crypto/src/math/ec/custom/djb/Curve25519FieldElement.cs
+++ b/crypto/src/math/ec/custom/djb/Curve25519FieldElement.cs
@@ -6,7 +6,7 @@ using Org.BouncyCastle.Utilities;
 namespace Org.BouncyCastle.Math.EC.Custom.Djb
 {
     internal class Curve25519FieldElement
-        :   ECFieldElement
+        : AbstractFpFieldElement
     {
         public static readonly BigInteger Q = Curve25519.q;
 
diff --git a/crypto/src/math/ec/custom/gm/SM2P256V1FieldElement.cs b/crypto/src/math/ec/custom/gm/SM2P256V1FieldElement.cs
index 4f6428f9e..087a040f2 100644
--- a/crypto/src/math/ec/custom/gm/SM2P256V1FieldElement.cs
+++ b/crypto/src/math/ec/custom/gm/SM2P256V1FieldElement.cs
@@ -6,7 +6,7 @@ using Org.BouncyCastle.Utilities;
 namespace Org.BouncyCastle.Math.EC.Custom.GM
 {
     internal class SM2P256V1FieldElement
-        : ECFieldElement
+        : AbstractFpFieldElement
     {
         public static readonly BigInteger Q = SM2P256V1Curve.q;
 
diff --git a/crypto/src/math/ec/custom/sec/SecP128R1FieldElement.cs b/crypto/src/math/ec/custom/sec/SecP128R1FieldElement.cs
index fa7951d5d..5912a87e8 100644
--- a/crypto/src/math/ec/custom/sec/SecP128R1FieldElement.cs
+++ b/crypto/src/math/ec/custom/sec/SecP128R1FieldElement.cs
@@ -6,7 +6,7 @@ using Org.BouncyCastle.Utilities;
 namespace Org.BouncyCastle.Math.EC.Custom.Sec
 {
     internal class SecP128R1FieldElement
-        : ECFieldElement
+        : AbstractFpFieldElement
     {
         public static readonly BigInteger Q = SecP128R1Curve.q;
 
diff --git a/crypto/src/math/ec/custom/sec/SecP160R1FieldElement.cs b/crypto/src/math/ec/custom/sec/SecP160R1FieldElement.cs
index d1fc75644..3ab11bdae 100644
--- a/crypto/src/math/ec/custom/sec/SecP160R1FieldElement.cs
+++ b/crypto/src/math/ec/custom/sec/SecP160R1FieldElement.cs
@@ -6,7 +6,7 @@ using Org.BouncyCastle.Utilities;
 namespace Org.BouncyCastle.Math.EC.Custom.Sec
 {
     internal class SecP160R1FieldElement
-        : ECFieldElement
+        : AbstractFpFieldElement
     {
         public static readonly BigInteger Q = SecP160R1Curve.q;
 
diff --git a/crypto/src/math/ec/custom/sec/SecP160R2FieldElement.cs b/crypto/src/math/ec/custom/sec/SecP160R2FieldElement.cs
index bdb5245b2..9d8131857 100644
--- a/crypto/src/math/ec/custom/sec/SecP160R2FieldElement.cs
+++ b/crypto/src/math/ec/custom/sec/SecP160R2FieldElement.cs
@@ -6,7 +6,7 @@ using Org.BouncyCastle.Utilities;
 namespace Org.BouncyCastle.Math.EC.Custom.Sec
 {
     internal class SecP160R2FieldElement
-        : ECFieldElement
+        : AbstractFpFieldElement
     {
         public static readonly BigInteger Q = SecP160R2Curve.q;
 
diff --git a/crypto/src/math/ec/custom/sec/SecP192K1FieldElement.cs b/crypto/src/math/ec/custom/sec/SecP192K1FieldElement.cs
index dce377035..54b72573c 100644
--- a/crypto/src/math/ec/custom/sec/SecP192K1FieldElement.cs
+++ b/crypto/src/math/ec/custom/sec/SecP192K1FieldElement.cs
@@ -7,7 +7,7 @@ using Org.BouncyCastle.Utilities;
 namespace Org.BouncyCastle.Math.EC.Custom.Sec
 {
     internal class SecP192K1FieldElement
-        : ECFieldElement
+        : AbstractFpFieldElement
     {
         public static readonly BigInteger Q = SecP192K1Curve.q;
 
diff --git a/crypto/src/math/ec/custom/sec/SecP192R1FieldElement.cs b/crypto/src/math/ec/custom/sec/SecP192R1FieldElement.cs
index 45bcb00f0..f3e12b542 100644
--- a/crypto/src/math/ec/custom/sec/SecP192R1FieldElement.cs
+++ b/crypto/src/math/ec/custom/sec/SecP192R1FieldElement.cs
@@ -6,7 +6,7 @@ using Org.BouncyCastle.Utilities;
 namespace Org.BouncyCastle.Math.EC.Custom.Sec
 {
     internal class SecP192R1FieldElement
-        : ECFieldElement
+        : AbstractFpFieldElement
     {
         public static readonly BigInteger Q = SecP192R1Curve.q;
 
diff --git a/crypto/src/math/ec/custom/sec/SecP224K1FieldElement.cs b/crypto/src/math/ec/custom/sec/SecP224K1FieldElement.cs
index fec07436a..ef53a88d6 100644
--- a/crypto/src/math/ec/custom/sec/SecP224K1FieldElement.cs
+++ b/crypto/src/math/ec/custom/sec/SecP224K1FieldElement.cs
@@ -7,7 +7,7 @@ using Org.BouncyCastle.Utilities;
 namespace Org.BouncyCastle.Math.EC.Custom.Sec
 {
     internal class SecP224K1FieldElement
-        : ECFieldElement
+        : AbstractFpFieldElement
     {
         public static readonly BigInteger Q = SecP224K1Curve.q;
 
diff --git a/crypto/src/math/ec/custom/sec/SecP224R1FieldElement.cs b/crypto/src/math/ec/custom/sec/SecP224R1FieldElement.cs
index 2b9a06564..5780b7481 100644
--- a/crypto/src/math/ec/custom/sec/SecP224R1FieldElement.cs
+++ b/crypto/src/math/ec/custom/sec/SecP224R1FieldElement.cs
@@ -6,7 +6,7 @@ using Org.BouncyCastle.Utilities;
 namespace Org.BouncyCastle.Math.EC.Custom.Sec
 {
     internal class SecP224R1FieldElement
-        : ECFieldElement
+        : AbstractFpFieldElement
     {
         public static readonly BigInteger Q = SecP224R1Curve.q;
 
diff --git a/crypto/src/math/ec/custom/sec/SecP256K1FieldElement.cs b/crypto/src/math/ec/custom/sec/SecP256K1FieldElement.cs
index 473113d0f..9a604bdb7 100644
--- a/crypto/src/math/ec/custom/sec/SecP256K1FieldElement.cs
+++ b/crypto/src/math/ec/custom/sec/SecP256K1FieldElement.cs
@@ -7,7 +7,7 @@ using Org.BouncyCastle.Utilities;
 namespace Org.BouncyCastle.Math.EC.Custom.Sec
 {
     internal class SecP256K1FieldElement
-        : ECFieldElement
+        : AbstractFpFieldElement
     {
         public static readonly BigInteger Q = SecP256K1Curve.q;
 
diff --git a/crypto/src/math/ec/custom/sec/SecP256R1FieldElement.cs b/crypto/src/math/ec/custom/sec/SecP256R1FieldElement.cs
index d7838aead..808e99ea6 100644
--- a/crypto/src/math/ec/custom/sec/SecP256R1FieldElement.cs
+++ b/crypto/src/math/ec/custom/sec/SecP256R1FieldElement.cs
@@ -6,7 +6,7 @@ using Org.BouncyCastle.Utilities;
 namespace Org.BouncyCastle.Math.EC.Custom.Sec
 {
     internal class SecP256R1FieldElement
-        : ECFieldElement
+        : AbstractFpFieldElement
     {
         public static readonly BigInteger Q = SecP256R1Curve.q;
 
diff --git a/crypto/src/math/ec/custom/sec/SecP384R1FieldElement.cs b/crypto/src/math/ec/custom/sec/SecP384R1FieldElement.cs
index 18d48a57d..7eedccae6 100644
--- a/crypto/src/math/ec/custom/sec/SecP384R1FieldElement.cs
+++ b/crypto/src/math/ec/custom/sec/SecP384R1FieldElement.cs
@@ -6,7 +6,7 @@ using Org.BouncyCastle.Utilities;
 namespace Org.BouncyCastle.Math.EC.Custom.Sec
 {
     internal class SecP384R1FieldElement
-        : ECFieldElement
+        : AbstractFpFieldElement
     {
         public static readonly BigInteger Q = SecP384R1Curve.q;
 
diff --git a/crypto/src/math/ec/custom/sec/SecP521R1FieldElement.cs b/crypto/src/math/ec/custom/sec/SecP521R1FieldElement.cs
index 6f02a7eb5..96658a8e5 100644
--- a/crypto/src/math/ec/custom/sec/SecP521R1FieldElement.cs
+++ b/crypto/src/math/ec/custom/sec/SecP521R1FieldElement.cs
@@ -6,7 +6,7 @@ using Org.BouncyCastle.Utilities;
 namespace Org.BouncyCastle.Math.EC.Custom.Sec
 {
     internal class SecP521R1FieldElement
-        : ECFieldElement
+        : AbstractFpFieldElement
     {
         public static readonly BigInteger Q = SecP521R1Curve.q;
 
diff --git a/crypto/src/math/ec/custom/sec/SecT113FieldElement.cs b/crypto/src/math/ec/custom/sec/SecT113FieldElement.cs
index 9ba25d987..bb87b00fc 100644
--- a/crypto/src/math/ec/custom/sec/SecT113FieldElement.cs
+++ b/crypto/src/math/ec/custom/sec/SecT113FieldElement.cs
@@ -6,7 +6,7 @@ using Org.BouncyCastle.Utilities;
 namespace Org.BouncyCastle.Math.EC.Custom.Sec
 {
     internal class SecT113FieldElement
-        : ECFieldElement
+        : AbstractF2mFieldElement
     {
         protected internal readonly ulong[] x;
 
@@ -150,6 +150,11 @@ namespace Org.BouncyCastle.Math.EC.Custom.Sec
             return new SecT113FieldElement(z);
         }
 
+        public override int Trace()
+        {
+            return (int)SecT113Field.Trace(x);
+        }
+
         public override ECFieldElement Invert()
         {
             ulong[] z = Nat128.Create64();
diff --git a/crypto/src/math/ec/custom/sec/SecT131FieldElement.cs b/crypto/src/math/ec/custom/sec/SecT131FieldElement.cs
index c38e8eb0a..f96c7ca39 100644
--- a/crypto/src/math/ec/custom/sec/SecT131FieldElement.cs
+++ b/crypto/src/math/ec/custom/sec/SecT131FieldElement.cs
@@ -6,7 +6,7 @@ using Org.BouncyCastle.Utilities;
 namespace Org.BouncyCastle.Math.EC.Custom.Sec
 {
     internal class SecT131FieldElement
-        : ECFieldElement
+        : AbstractF2mFieldElement
     {
         protected internal readonly ulong[] x;
 
@@ -150,6 +150,11 @@ namespace Org.BouncyCastle.Math.EC.Custom.Sec
             return new SecT131FieldElement(z);
         }
 
+        public override int Trace()
+        {
+            return (int)SecT131Field.Trace(x);
+        }
+
         public override ECFieldElement Invert()
         {
             ulong[] z = Nat192.Create64();
diff --git a/crypto/src/math/ec/custom/sec/SecT163FieldElement.cs b/crypto/src/math/ec/custom/sec/SecT163FieldElement.cs
index 07bd07652..903645999 100644
--- a/crypto/src/math/ec/custom/sec/SecT163FieldElement.cs
+++ b/crypto/src/math/ec/custom/sec/SecT163FieldElement.cs
@@ -6,7 +6,7 @@ using Org.BouncyCastle.Utilities;
 namespace Org.BouncyCastle.Math.EC.Custom.Sec
 {
     internal class SecT163FieldElement
-        : ECFieldElement
+        : AbstractF2mFieldElement
     {
         protected internal readonly ulong[] x;
 
@@ -150,6 +150,11 @@ namespace Org.BouncyCastle.Math.EC.Custom.Sec
             return new SecT163FieldElement(z);
         }
 
+        public override int Trace()
+        {
+            return (int)SecT163Field.Trace(x);
+        }
+
         public override ECFieldElement Invert()
         {
             ulong[] z = Nat192.Create64();
diff --git a/crypto/src/math/ec/custom/sec/SecT193FieldElement.cs b/crypto/src/math/ec/custom/sec/SecT193FieldElement.cs
index d04e68d3f..9813bcb01 100644
--- a/crypto/src/math/ec/custom/sec/SecT193FieldElement.cs
+++ b/crypto/src/math/ec/custom/sec/SecT193FieldElement.cs
@@ -6,7 +6,7 @@ using Org.BouncyCastle.Utilities;
 namespace Org.BouncyCastle.Math.EC.Custom.Sec
 {
     internal class SecT193FieldElement
-        : ECFieldElement
+        : AbstractF2mFieldElement
     {
         protected internal readonly ulong[] x;
 
@@ -150,6 +150,11 @@ namespace Org.BouncyCastle.Math.EC.Custom.Sec
             return new SecT193FieldElement(z);
         }
 
+        public override int Trace()
+        {
+            return (int)SecT193Field.Trace(x);
+        }
+
         public override ECFieldElement Invert()
         {
             ulong[] z = Nat256.Create64();
diff --git a/crypto/src/math/ec/custom/sec/SecT233FieldElement.cs b/crypto/src/math/ec/custom/sec/SecT233FieldElement.cs
index 64d09bd6d..fbfe35e13 100644
--- a/crypto/src/math/ec/custom/sec/SecT233FieldElement.cs
+++ b/crypto/src/math/ec/custom/sec/SecT233FieldElement.cs
@@ -6,7 +6,7 @@ using Org.BouncyCastle.Utilities;
 namespace Org.BouncyCastle.Math.EC.Custom.Sec
 {
     internal class SecT233FieldElement
-        : ECFieldElement
+        : AbstractF2mFieldElement
     {
         protected internal readonly ulong[] x;
 
@@ -150,6 +150,11 @@ namespace Org.BouncyCastle.Math.EC.Custom.Sec
             return new SecT233FieldElement(z);
         }
 
+        public override int Trace()
+        {
+            return (int)SecT233Field.Trace(x);
+        }
+
         public override ECFieldElement Invert()
         {
             ulong[] z = Nat256.Create64();
diff --git a/crypto/src/math/ec/custom/sec/SecT239FieldElement.cs b/crypto/src/math/ec/custom/sec/SecT239FieldElement.cs
index 18563f746..b1b58e89b 100644
--- a/crypto/src/math/ec/custom/sec/SecT239FieldElement.cs
+++ b/crypto/src/math/ec/custom/sec/SecT239FieldElement.cs
@@ -6,7 +6,7 @@ using Org.BouncyCastle.Utilities;
 namespace Org.BouncyCastle.Math.EC.Custom.Sec
 {
     internal class SecT239FieldElement
-        : ECFieldElement
+        : AbstractF2mFieldElement
     {
         protected internal readonly ulong[] x;
 
@@ -150,6 +150,11 @@ namespace Org.BouncyCastle.Math.EC.Custom.Sec
             return new SecT239FieldElement(z);
         }
 
+        public override int Trace()
+        {
+            return (int)SecT239Field.Trace(x);
+        }
+
         public override ECFieldElement Invert()
         {
             ulong[] z = Nat256.Create64();
diff --git a/crypto/src/math/ec/custom/sec/SecT283FieldElement.cs b/crypto/src/math/ec/custom/sec/SecT283FieldElement.cs
index b054bedfb..c1bb2e30c 100644
--- a/crypto/src/math/ec/custom/sec/SecT283FieldElement.cs
+++ b/crypto/src/math/ec/custom/sec/SecT283FieldElement.cs
@@ -6,7 +6,7 @@ using Org.BouncyCastle.Utilities;
 namespace Org.BouncyCastle.Math.EC.Custom.Sec
 {
     internal class SecT283FieldElement
-        : ECFieldElement
+        : AbstractF2mFieldElement
     {
         protected internal readonly ulong[] x;
 
@@ -150,6 +150,11 @@ namespace Org.BouncyCastle.Math.EC.Custom.Sec
             return new SecT283FieldElement(z);
         }
 
+        public override int Trace()
+        {
+            return (int)SecT283Field.Trace(x);
+        }
+
         public override ECFieldElement Invert()
         {
             ulong[] z = Nat320.Create64();
diff --git a/crypto/src/math/ec/custom/sec/SecT409FieldElement.cs b/crypto/src/math/ec/custom/sec/SecT409FieldElement.cs
index 7076905bb..68a63312d 100644
--- a/crypto/src/math/ec/custom/sec/SecT409FieldElement.cs
+++ b/crypto/src/math/ec/custom/sec/SecT409FieldElement.cs
@@ -6,7 +6,7 @@ using Org.BouncyCastle.Utilities;
 namespace Org.BouncyCastle.Math.EC.Custom.Sec
 {
     internal class SecT409FieldElement
-        : ECFieldElement
+        : AbstractF2mFieldElement
     {
         protected internal readonly ulong[] x;
 
@@ -150,6 +150,11 @@ namespace Org.BouncyCastle.Math.EC.Custom.Sec
             return new SecT409FieldElement(z);
         }
 
+        public override int Trace()
+        {
+            return (int)SecT409Field.Trace(x);
+        }
+
         public override ECFieldElement Invert()
         {
             ulong[] z = Nat448.Create64();
diff --git a/crypto/src/math/ec/custom/sec/SecT571FieldElement.cs b/crypto/src/math/ec/custom/sec/SecT571FieldElement.cs
index 5f28c01be..c9f3aa5c0 100644
--- a/crypto/src/math/ec/custom/sec/SecT571FieldElement.cs
+++ b/crypto/src/math/ec/custom/sec/SecT571FieldElement.cs
@@ -6,7 +6,7 @@ using Org.BouncyCastle.Utilities;
 namespace Org.BouncyCastle.Math.EC.Custom.Sec
 {
     internal class SecT571FieldElement
-        : ECFieldElement
+        : AbstractF2mFieldElement
     {
         protected internal readonly ulong[] x;
 
@@ -150,6 +150,11 @@ namespace Org.BouncyCastle.Math.EC.Custom.Sec
             return new SecT571FieldElement(z);
         }
 
+        public override int Trace()
+        {
+            return (int)SecT571Field.Trace(x);
+        }
+
         public override ECFieldElement Invert()
         {
             ulong[] z = Nat576.Create64();
diff --git a/crypto/src/math/ec/multiplier/AbstractECMultiplier.cs b/crypto/src/math/ec/multiplier/AbstractECMultiplier.cs
index 517881323..c2580c852 100644
--- a/crypto/src/math/ec/multiplier/AbstractECMultiplier.cs
+++ b/crypto/src/math/ec/multiplier/AbstractECMultiplier.cs
@@ -16,9 +16,14 @@
              * Although the various multipliers ought not to produce invalid output under normal
              * circumstances, a final check here is advised to guard against fault attacks.
              */
-            return ECAlgorithms.ValidatePoint(result);
+            return CheckResult(result);
         }
 
         protected abstract ECPoint MultiplyPositive(ECPoint p, BigInteger k);
+
+        protected virtual ECPoint CheckResult(ECPoint p)
+        {
+            return ECAlgorithms.ImplCheckResult(p);
+        }
     }
 }
diff --git a/crypto/src/math/ec/multiplier/FixedPointCombMultiplier.cs b/crypto/src/math/ec/multiplier/FixedPointCombMultiplier.cs
index adaedb809..505832442 100644
--- a/crypto/src/math/ec/multiplier/FixedPointCombMultiplier.cs
+++ b/crypto/src/math/ec/multiplier/FixedPointCombMultiplier.cs
@@ -52,11 +52,5 @@ namespace Org.BouncyCastle.Math.EC.Multiplier
 
             return R.Add(info.Offset);
         }
-
-        [Obsolete("Is no longer used; remove any overrides in subclasses.")]
-        protected virtual int GetWidthForCombSize(int combSize)
-        {
-            return combSize > 257 ? 6 : 5;
-        }
     }
 }
diff --git a/crypto/src/math/ec/multiplier/FixedPointPreCompInfo.cs b/crypto/src/math/ec/multiplier/FixedPointPreCompInfo.cs
index 4c0b404df..5d6af9e5d 100644
--- a/crypto/src/math/ec/multiplier/FixedPointPreCompInfo.cs
+++ b/crypto/src/math/ec/multiplier/FixedPointPreCompInfo.cs
@@ -11,13 +11,6 @@ namespace Org.BouncyCastle.Math.EC.Multiplier
         protected ECPoint m_offset = null;
 
         /**
-         * Array holding the precomputed <code>ECPoint</code>s used for a fixed
-         * point multiplication.
-         */
-        [Obsolete("Will be removed")]
-		protected ECPoint[] m_preComp = null;
-
-        /**
          * Lookup table for the precomputed <code>ECPoint</code>s used for a fixed point multiplication.
          */
         protected ECLookupTable m_lookupTable = null;
@@ -41,13 +34,6 @@ namespace Org.BouncyCastle.Math.EC.Multiplier
 			set { this.m_offset = value; }
 		}
 
-        [Obsolete("Use 'LookupTable' property instead.")]
-        public virtual ECPoint[] PreComp
-        {
-            get { return m_preComp; }
-            set { this.m_preComp = value; }
-        }
-
         public virtual int Width
         {
             get { return m_width; }
diff --git a/crypto/src/math/ec/multiplier/FixedPointUtilities.cs b/crypto/src/math/ec/multiplier/FixedPointUtilities.cs
index cc7203314..88f178e24 100644
--- a/crypto/src/math/ec/multiplier/FixedPointUtilities.cs
+++ b/crypto/src/math/ec/multiplier/FixedPointUtilities.cs
@@ -14,36 +14,40 @@ namespace Org.BouncyCastle.Math.EC.Multiplier
 
         public static FixedPointPreCompInfo GetFixedPointPreCompInfo(PreCompInfo preCompInfo)
         {
-            if ((preCompInfo != null) && (preCompInfo is FixedPointPreCompInfo))
-            {
-                return (FixedPointPreCompInfo)preCompInfo;
-            }
-
-            return new FixedPointPreCompInfo();
+            return preCompInfo as FixedPointPreCompInfo;
         }
 
-        [Obsolete("Use 'Precompute(ECPoint)' instead, as minWidth parameter is now ignored")]
-        public static FixedPointPreCompInfo Precompute(ECPoint p, int minWidth)
+        public static FixedPointPreCompInfo Precompute(ECPoint p)
         {
-            return Precompute(p);
+            return (FixedPointPreCompInfo)p.Curve.Precompute(p, PRECOMP_NAME, new FixedPointCallback(p));
         }
 
-        public static FixedPointPreCompInfo Precompute(ECPoint p)
+        private class FixedPointCallback
+            : IPreCompCallback
         {
-            ECCurve c = p.Curve;
-            int minWidth = GetCombSize(c) > 257 ? 6 : 5;
+            private readonly ECPoint m_p;
 
-            int n = 1 << minWidth;
-            FixedPointPreCompInfo info = GetFixedPointPreCompInfo(c.GetPreCompInfo(p, PRECOMP_NAME));
-            ECPoint[] lookupTable = info.PreComp;
+            internal FixedPointCallback(ECPoint p)
+            {
+                this.m_p = p;
+            }
 
-            if (lookupTable == null || lookupTable.Length < n)
+            public PreCompInfo Precompute(PreCompInfo existing)
             {
-                int bits = GetCombSize(c);
+                FixedPointPreCompInfo existingFP = (existing is FixedPointPreCompInfo) ? (FixedPointPreCompInfo)existing : null;
+
+                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] = p;
+                pow2Table[0] = m_p;
                 for (int i = 1; i < minWidth; ++i)
                 {
                     pow2Table[i] = pow2Table[i - 1].TimesPow2(d);
@@ -53,8 +57,8 @@ namespace Org.BouncyCastle.Math.EC.Multiplier
                 pow2Table[minWidth] = pow2Table[0].Subtract(pow2Table[1]);
 
                 c.NormalizeAll(pow2Table);
-    
-                lookupTable = new ECPoint[n];
+
+                ECPoint[] lookupTable = new ECPoint[n];
                 lookupTable[0] = pow2Table[0];
 
                 for (int bit = minWidth - 1; bit >= 0; --bit)
@@ -70,15 +74,22 @@ namespace Org.BouncyCastle.Math.EC.Multiplier
 
                 c.NormalizeAll(lookupTable);
 
-                info.LookupTable = c.CreateCacheSafeLookupTable(lookupTable, 0, lookupTable.Length);
-                info.Offset = pow2Table[minWidth];
-                info.PreComp = lookupTable;
-                info.Width = minWidth;
+                FixedPointPreCompInfo result = new FixedPointPreCompInfo();
+                result.LookupTable = c.CreateCacheSafeLookupTable(lookupTable, 0, lookupTable.Length);
+                result.Offset = pow2Table[minWidth];
+                result.Width = minWidth;
+                return result;
+            }
 
-                c.SetPreCompInfo(p, PRECOMP_NAME, info);
+            private bool CheckExisting(FixedPointPreCompInfo existingFP, int n)
+            {
+                return existingFP != null && CheckTable(existingFP.LookupTable, n);
             }
 
-            return info;
+            private bool CheckTable(ECLookupTable table, int n)
+            {
+                return table != null && table.Size >= n;
+            }
         }
     }
 }
diff --git a/crypto/src/math/ec/multiplier/IPreCompCallback.cs b/crypto/src/math/ec/multiplier/IPreCompCallback.cs
new file mode 100644
index 000000000..e64ae834d
--- /dev/null
+++ b/crypto/src/math/ec/multiplier/IPreCompCallback.cs
@@ -0,0 +1,9 @@
+using System;
+
+namespace Org.BouncyCastle.Math.EC.Multiplier
+{
+    public interface IPreCompCallback
+    {
+        PreCompInfo Precompute(PreCompInfo existing);
+    }
+}
diff --git a/crypto/src/math/ec/multiplier/ValidityPreCompInfo.cs b/crypto/src/math/ec/multiplier/ValidityPreCompInfo.cs
new file mode 100644
index 000000000..7ec2cbb95
--- /dev/null
+++ b/crypto/src/math/ec/multiplier/ValidityPreCompInfo.cs
@@ -0,0 +1,44 @@
+using System;
+
+namespace Org.BouncyCastle.Math.EC.Multiplier
+{
+    internal class ValidityPreCompInfo
+        : PreCompInfo
+    {
+        internal static readonly string PRECOMP_NAME = "bc_validity";
+
+        private bool failed = false;
+        private bool curveEquationPassed = false;
+        private bool orderPassed = false;
+
+        internal bool HasFailed()
+        {
+            return failed;
+        }
+
+        internal void ReportFailed()
+        {
+            failed = true;
+        }
+
+        internal bool HasCurveEquationPassed()
+        {
+            return curveEquationPassed;
+        }
+
+        internal void ReportCurveEquationPassed()
+        {
+            curveEquationPassed = true;
+        }
+
+        internal bool HasOrderPassed()
+        {
+            return orderPassed;
+        }
+
+        internal void ReportOrderPassed()
+        {
+            orderPassed = true;
+        }
+    }
+}
diff --git a/crypto/src/math/ec/multiplier/WNafUtilities.cs b/crypto/src/math/ec/multiplier/WNafUtilities.cs
index 7d565dfbd..e893abd49 100644
--- a/crypto/src/math/ec/multiplier/WNafUtilities.cs
+++ b/crypto/src/math/ec/multiplier/WNafUtilities.cs
@@ -287,12 +287,7 @@ namespace Org.BouncyCastle.Math.EC.Multiplier
 
         public static WNafPreCompInfo GetWNafPreCompInfo(PreCompInfo preCompInfo)
         {
-            if ((preCompInfo != null) && (preCompInfo is WNafPreCompInfo))
-            {
-                return (WNafPreCompInfo)preCompInfo;
-            }
-
-            return new WNafPreCompInfo();
+            return preCompInfo as WNafPreCompInfo;
         }
 
         /**
@@ -333,106 +328,178 @@ namespace Org.BouncyCastle.Math.EC.Multiplier
             WNafPreCompInfo wnafPreCompP = Precompute(p, width, includeNegated);
 
             ECPoint q = pointMap.Map(p);
-            WNafPreCompInfo wnafPreCompQ = GetWNafPreCompInfo(c.GetPreCompInfo(q, PRECOMP_NAME));
+            c.Precompute(q, PRECOMP_NAME, new MapPointCallback(wnafPreCompP, includeNegated, pointMap));
+            return q;
+        }
 
-            ECPoint twiceP = wnafPreCompP.Twice;
-            if (twiceP != null)
-            {
-                ECPoint twiceQ = pointMap.Map(twiceP);
-                wnafPreCompQ.Twice = twiceQ;
-            }
+        public static WNafPreCompInfo Precompute(ECPoint p, int width, bool includeNegated)
+        {
+            return (WNafPreCompInfo)p.Curve.Precompute(p, PRECOMP_NAME, new WNafCallback(p, width, includeNegated));
+        }
+
+        private static byte[] Trim(byte[] a, int length)
+        {
+            byte[] result = new byte[length];
+            Array.Copy(a, 0, result, 0, result.Length);
+            return result;
+        }
+
+        private static int[] Trim(int[] a, int length)
+        {
+            int[] result = new int[length];
+            Array.Copy(a, 0, result, 0, result.Length);
+            return result;
+        }
+
+        private static ECPoint[] ResizeTable(ECPoint[] a, int length)
+        {
+            ECPoint[] result = new ECPoint[length];
+            Array.Copy(a, 0, result, 0, a.Length);
+            return result;
+        }
+
+        private class MapPointCallback
+            : IPreCompCallback
+        {
+            private readonly WNafPreCompInfo m_wnafPreCompP;
+            private readonly bool m_includeNegated;
+            private readonly ECPointMap m_pointMap;
 
-            ECPoint[] preCompP = wnafPreCompP.PreComp;
-            ECPoint[] preCompQ = new ECPoint[preCompP.Length];
-            for (int i = 0; i < preCompP.Length; ++i)
+            internal MapPointCallback(WNafPreCompInfo wnafPreCompP, bool includeNegated, ECPointMap pointMap)
             {
-                preCompQ[i] = pointMap.Map(preCompP[i]);
+                this.m_wnafPreCompP = wnafPreCompP;
+                this.m_includeNegated = includeNegated;
+                this.m_pointMap = pointMap;
             }
-            wnafPreCompQ.PreComp = preCompQ;
 
-            if (includeNegated)
+            public PreCompInfo Precompute(PreCompInfo existing)
             {
-                ECPoint[] preCompNegQ = new ECPoint[preCompQ.Length];
-                for (int i = 0; i < preCompNegQ.Length; ++i)
+                WNafPreCompInfo result = new WNafPreCompInfo();
+
+                ECPoint twiceP = m_wnafPreCompP.Twice;
+                if (twiceP != null)
                 {
-                    preCompNegQ[i] = preCompQ[i].Negate();
+                    ECPoint twiceQ = m_pointMap.Map(twiceP);
+                    result.Twice = twiceQ;
                 }
-                wnafPreCompQ.PreCompNeg = preCompNegQ;
-            }
 
-            c.SetPreCompInfo(q, PRECOMP_NAME, wnafPreCompQ);
+                ECPoint[] preCompP = m_wnafPreCompP.PreComp;
+                ECPoint[] preCompQ = new ECPoint[preCompP.Length];
+                for (int i = 0; i < preCompP.Length; ++i)
+                {
+                    preCompQ[i] = m_pointMap.Map(preCompP[i]);
+                }
+                result.PreComp = preCompQ;
 
-            return q;
+                if (m_includeNegated)
+                {
+                    ECPoint[] preCompNegQ = new ECPoint[preCompQ.Length];
+                    for (int i = 0; i < preCompNegQ.Length; ++i)
+                    {
+                        preCompNegQ[i] = preCompQ[i].Negate();
+                    }
+                    result.PreCompNeg = preCompNegQ;
+                }
+
+                return result;
+            }
         }
 
-        public static WNafPreCompInfo Precompute(ECPoint p, int width, bool includeNegated)
+        private class WNafCallback
+            : IPreCompCallback
         {
-            ECCurve c = p.Curve;
-            WNafPreCompInfo wnafPreCompInfo = GetWNafPreCompInfo(c.GetPreCompInfo(p, PRECOMP_NAME));
+            private readonly ECPoint m_p;
+            private readonly int m_width;
+            private readonly bool m_includeNegated;
 
-            int iniPreCompLen = 0, reqPreCompLen = 1 << System.Math.Max(0, width - 2);
-
-            ECPoint[] preComp = wnafPreCompInfo.PreComp;
-            if (preComp == null)
+            internal WNafCallback(ECPoint p, int width, bool includeNegated)
             {
-                preComp = EMPTY_POINTS;
-            }
-            else
-            {
-                iniPreCompLen = preComp.Length;
+                this.m_p = p;
+                this.m_width = width;
+                this.m_includeNegated = includeNegated;
             }
 
-            if (iniPreCompLen < reqPreCompLen)
+            public PreCompInfo Precompute(PreCompInfo existing)
             {
-                preComp = ResizeTable(preComp, reqPreCompLen);
+                WNafPreCompInfo existingWNaf = existing as WNafPreCompInfo;
+
+                int reqPreCompLen = 1 << System.Math.Max(0, m_width - 2);
+
+                if (CheckExisting(existingWNaf, reqPreCompLen, m_includeNegated))
+                    return existingWNaf;
 
-                if (reqPreCompLen == 1)
+                ECCurve c = m_p.Curve;
+                ECPoint[] preComp = null, preCompNeg = null;
+                ECPoint twiceP = null;
+
+                if (existingWNaf != null)
+                {
+                    preComp = existingWNaf.PreComp;
+                    preCompNeg = existingWNaf.PreCompNeg;
+                    twiceP = existingWNaf.Twice;
+                }
+
+                int iniPreCompLen = 0;
+                if (preComp == null)
                 {
-                    preComp[0] = p.Normalize();
+                    preComp = EMPTY_POINTS;
                 }
                 else
                 {
-                    int curPreCompLen = iniPreCompLen;
-                    if (curPreCompLen == 0)
-                    {
-                        preComp[0] = p;
-                        curPreCompLen = 1;
-                    }
+                    iniPreCompLen = preComp.Length;
+                }
 
-                    ECFieldElement iso = null;
+                if (iniPreCompLen < reqPreCompLen)
+                {
+                    preComp = WNafUtilities.ResizeTable(preComp, reqPreCompLen);
 
-                    if (reqPreCompLen == 2)
+                    if (reqPreCompLen == 1)
                     {
-                        preComp[1] = p.ThreeTimes();
+                        preComp[0] = m_p.Normalize();
                     }
                     else
                     {
-                        ECPoint twiceP = wnafPreCompInfo.Twice, last = preComp[curPreCompLen - 1];
-                        if (twiceP == null)
+                        int curPreCompLen = iniPreCompLen;
+                        if (curPreCompLen == 0)
+                        {
+                            preComp[0] = m_p;
+                            curPreCompLen = 1;
+                        }
+
+                        ECFieldElement iso = null;
+
+                        if (reqPreCompLen == 2)
+                        {
+                            preComp[1] = m_p.ThreeTimes();
+                        }
+                        else
                         {
-                            twiceP = preComp[0].Twice();
-                            wnafPreCompInfo.Twice = twiceP;
-
-                            /*
-                             * For Fp curves with Jacobian projective coordinates, use a (quasi-)isomorphism
-                             * where 'twiceP' is "affine", so that the subsequent additions are cheaper. This
-                             * also requires scaling the initial point's X, Y coordinates, and reversing the
-                             * isomorphism as part of the subsequent normalization.
-                             * 
-                             *  NOTE: The correctness of this optimization depends on:
-                             *      1) additions do not use the curve's A, B coefficients.
-                             *      2) no special cases (i.e. Q +/- Q) when calculating 1P, 3P, 5P, ...
-                             */
-                            if (!twiceP.IsInfinity && ECAlgorithms.IsFpCurve(c) && c.FieldSize >= 64)
+                            ECPoint isoTwiceP = twiceP, last = preComp[curPreCompLen - 1];
+                            if (isoTwiceP == null)
                             {
-                                switch (c.CoordinateSystem)
+                                isoTwiceP = preComp[0].Twice();
+                                twiceP = isoTwiceP;
+
+                                /*
+                                 * For Fp curves with Jacobian projective coordinates, use a (quasi-)isomorphism
+                                 * where 'twiceP' is "affine", so that the subsequent additions are cheaper. This
+                                 * also requires scaling the initial point's X, Y coordinates, and reversing the
+                                 * isomorphism as part of the subsequent normalization.
+                                 * 
+                                 *  NOTE: The correctness of this optimization depends on:
+                                 *      1) additions do not use the curve's A, B coefficients.
+                                 *      2) no special cases (i.e. Q +/- Q) when calculating 1P, 3P, 5P, ...
+                                 */
+                                if (!twiceP.IsInfinity && ECAlgorithms.IsFpCurve(c) && c.FieldSize >= 64)
                                 {
+                                    switch (c.CoordinateSystem)
+                                    {
                                     case ECCurve.COORD_JACOBIAN:
                                     case ECCurve.COORD_JACOBIAN_CHUDNOVSKY:
                                     case ECCurve.COORD_JACOBIAN_MODIFIED:
                                     {
                                         iso = twiceP.GetZCoord(0);
-                                        twiceP = c.CreatePoint(twiceP.XCoord.ToBigInteger(),
+                                        isoTwiceP = c.CreatePoint(twiceP.XCoord.ToBigInteger(),
                                             twiceP.YCoord.ToBigInteger());
 
                                         ECFieldElement iso2 = iso.Square(), iso3 = iso2.Multiply(iso);
@@ -444,81 +511,69 @@ namespace Org.BouncyCastle.Math.EC.Multiplier
                                         }
                                         break;
                                     }
+                                    }
                                 }
                             }
-                        }
 
-                        while (curPreCompLen < reqPreCompLen)
-                        {
-                            /*
-                             * Compute the new ECPoints for the precomputation array. The values 1, 3,
-                             * 5, ..., 2^(width-1)-1 times p are computed
-                             */
-                            preComp[curPreCompLen++] = last = last.Add(twiceP);
+                            while (curPreCompLen < reqPreCompLen)
+                            {
+                                /*
+                                 * Compute the new ECPoints for the precomputation array. The values 1, 3,
+                                 * 5, ..., 2^(width-1)-1 times p are computed
+                                 */
+                                preComp[curPreCompLen++] = last = last.Add(isoTwiceP);
+                            }
                         }
-                    }
 
-                    /*
-                     * Having oft-used operands in affine form makes operations faster.
-                     */
-                    c.NormalizeAll(preComp, iniPreCompLen, reqPreCompLen - iniPreCompLen, iso);
+                        /*
+                         * Having oft-used operands in affine form makes operations faster.
+                         */
+                        c.NormalizeAll(preComp, iniPreCompLen, reqPreCompLen - iniPreCompLen, iso);
+                    }
                 }
-            }
-
-            wnafPreCompInfo.PreComp = preComp;
-
-            if (includeNegated)
-            {
-                ECPoint[] preCompNeg = wnafPreCompInfo.PreCompNeg;
 
-                int pos;
-                if (preCompNeg == null)
-                {
-                    pos = 0;
-                    preCompNeg = new ECPoint[reqPreCompLen]; 
-                }
-                else
+                if (m_includeNegated)
                 {
-                    pos = preCompNeg.Length;
-                    if (pos < reqPreCompLen)
+                    int pos;
+                    if (preCompNeg == null)
                     {
-                        preCompNeg = ResizeTable(preCompNeg, reqPreCompLen);
+                        pos = 0;
+                        preCompNeg = new ECPoint[reqPreCompLen]; 
+                    }
+                    else
+                    {
+                        pos = preCompNeg.Length;
+                        if (pos < reqPreCompLen)
+                        {
+                            preCompNeg = WNafUtilities.ResizeTable(preCompNeg, reqPreCompLen);
+                        }
                     }
-                }
 
-                while (pos < reqPreCompLen)
-                {
-                    preCompNeg[pos] = preComp[pos].Negate();
-                    ++pos;
+                    while (pos < reqPreCompLen)
+                    {
+                        preCompNeg[pos] = preComp[pos].Negate();
+                        ++pos;
+                    }
                 }
 
-                wnafPreCompInfo.PreCompNeg = preCompNeg;
+                WNafPreCompInfo result = new WNafPreCompInfo();
+                result.PreComp = preComp;
+                result.PreCompNeg = preCompNeg;
+                result.Twice = twiceP;
+                return result;
             }
 
-            c.SetPreCompInfo(p, PRECOMP_NAME, wnafPreCompInfo);
-
-            return wnafPreCompInfo;
-        }
-
-        private static byte[] Trim(byte[] a, int length)
-        {
-            byte[] result = new byte[length];
-            Array.Copy(a, 0, result, 0, result.Length);
-            return result;
-        }
-
-        private static int[] Trim(int[] a, int length)
-        {
-            int[] result = new int[length];
-            Array.Copy(a, 0, result, 0, result.Length);
-            return result;
-        }
+            private bool CheckExisting(WNafPreCompInfo existingWNaf, int reqPreCompLen, bool includeNegated)
+            {
+                return existingWNaf != null
+                    && CheckTable(existingWNaf.PreComp, reqPreCompLen)
+                    && (!includeNegated || CheckTable(existingWNaf.PreCompNeg, reqPreCompLen));
+            }
 
-        private static ECPoint[] ResizeTable(ECPoint[] a, int length)
-        {
-            ECPoint[] result = new ECPoint[length];
-            Array.Copy(a, 0, result, 0, a.Length);
-            return result;
+            private bool CheckTable(ECPoint[] table, int reqLen)
+            {
+                return table != null && table.Length >= reqLen;
+            }
         }
     }
 }
diff --git a/crypto/src/math/ec/multiplier/WTauNafMultiplier.cs b/crypto/src/math/ec/multiplier/WTauNafMultiplier.cs
index 1e7ddae91..4dce54440 100644
--- a/crypto/src/math/ec/multiplier/WTauNafMultiplier.cs
+++ b/crypto/src/math/ec/multiplier/WTauNafMultiplier.cs
@@ -36,7 +36,7 @@ namespace Org.BouncyCastle.Math.EC.Multiplier
 
             ZTauElement rho = Tnaf.PartModReduction(k, m, a, s, mu, (sbyte)10);
 
-            return MultiplyWTnaf(p, rho, curve.GetPreCompInfo(p, PRECOMP_NAME), a, mu);
+            return MultiplyWTnaf(p, rho, a, mu);
         }
 
         /**
@@ -50,7 +50,7 @@ namespace Org.BouncyCastle.Math.EC.Multiplier
         * @return <code>p</code> multiplied by <code>&#955;</code>.
         */
         private AbstractF2mPoint MultiplyWTnaf(AbstractF2mPoint p, ZTauElement lambda,
-            PreCompInfo preCompInfo, sbyte a, sbyte mu)
+            sbyte a, sbyte mu)
         {
             ZTauElement[] alpha = (a == 0) ? Tnaf.Alpha0 : Tnaf.Alpha1;
 
@@ -59,7 +59,7 @@ namespace Org.BouncyCastle.Math.EC.Multiplier
             sbyte[]u = Tnaf.TauAdicWNaf(mu, lambda, Tnaf.Width,
                 BigInteger.ValueOf(Tnaf.Pow2Width), tw, alpha);
 
-            return MultiplyFromWTnaf(p, u, preCompInfo);
+            return MultiplyFromWTnaf(p, u);
         }
         
         /**
@@ -71,24 +71,14 @@ namespace Org.BouncyCastle.Math.EC.Multiplier
         * @param u The the WTNAF of <code>&#955;</code>..
         * @return <code>&#955; * p</code>
         */
-        private static AbstractF2mPoint MultiplyFromWTnaf(AbstractF2mPoint p, sbyte[] u, PreCompInfo preCompInfo)
+        private static AbstractF2mPoint MultiplyFromWTnaf(AbstractF2mPoint p, sbyte[] u)
         {
             AbstractF2mCurve curve = (AbstractF2mCurve)p.Curve;
             sbyte a = (sbyte)curve.A.ToBigInteger().IntValue;
 
-            AbstractF2mPoint[] pu;
-            if ((preCompInfo == null) || !(preCompInfo is WTauNafPreCompInfo))
-            {
-                pu = Tnaf.GetPreComp(p, a);
-
-                WTauNafPreCompInfo pre = new WTauNafPreCompInfo();
-                pre.PreComp = pu;
-                curve.SetPreCompInfo(p, PRECOMP_NAME, pre);
-            }
-            else
-            {
-                pu = ((WTauNafPreCompInfo)preCompInfo).PreComp;
-            }
+            WTauNafCallback callback = new WTauNafCallback(p, a);
+            WTauNafPreCompInfo preCompInfo = (WTauNafPreCompInfo)curve.Precompute(p, PRECOMP_NAME, callback);
+            AbstractF2mPoint[] pu = preCompInfo.PreComp;
 
             // TODO Include negations in precomp (optionally) and use from here
             AbstractF2mPoint[] puNeg = new AbstractF2mPoint[pu.Length];
@@ -121,5 +111,28 @@ namespace Org.BouncyCastle.Math.EC.Multiplier
             }
             return q;
         }
+
+        private class WTauNafCallback
+            : IPreCompCallback
+        {
+            private readonly AbstractF2mPoint m_p;
+            private readonly sbyte m_a;
+
+            internal WTauNafCallback(AbstractF2mPoint p, sbyte a)
+            {
+                this.m_p = p;
+                this.m_a = a;
+            }
+
+            public PreCompInfo Precompute(PreCompInfo existing)
+            {
+                if (existing is WTauNafPreCompInfo)
+                    return existing;
+
+                WTauNafPreCompInfo result = new WTauNafPreCompInfo();
+                result.PreComp = Tnaf.GetPreComp(m_p, m_a);
+                return result;
+            }
+        }
     }
 }