Esempio n. 1
0
        internal static ECPoint ImplSumOfMultiplies(ECEndomorphism endomorphism, ECPoint[] ps, BigInteger[] ks)
        {
            int halfCount = ps.Length, fullCount = halfCount << 1;

            bool[]            negs  = new bool[fullCount];
            WNafPreCompInfo[] infos = new WNafPreCompInfo[fullCount];
            byte[][]          wnafs = new byte[fullCount][];

            ECPointMap pointMap = endomorphism.PointMap;

            for (int i = 0; i < halfCount; ++i)
            {
                int j0 = i << 1, j1 = j0 + 1;

                BigInteger kj0 = ks[j0]; negs[j0] = kj0.SignValue < 0; kj0 = kj0.Abs();
                BigInteger kj1 = ks[j1]; negs[j1] = kj1.SignValue < 0; kj1 = kj1.Abs();

                int minWidth = WNafUtilities.GetWindowSize(System.Math.Max(kj0.BitLength, kj1.BitLength), 8);

                ECPoint         P     = ps[i];
                WNafPreCompInfo infoP = WNafUtilities.Precompute(P, minWidth, true);
                ECPoint         Q     = EndoUtilities.MapPoint(endomorphism, P);
                WNafPreCompInfo infoQ = WNafUtilities.PrecomputeWithPointMap(Q, pointMap, infoP, true);

                int widthP = System.Math.Min(8, infoP.Width);
                int widthQ = System.Math.Min(8, infoQ.Width);

                infos[j0] = infoP;
                infos[j1] = infoQ;
                wnafs[j0] = WNafUtilities.GenerateWindowNaf(widthP, kj0);
                wnafs[j1] = WNafUtilities.GenerateWindowNaf(widthQ, kj1);
            }

            return(ImplSumOfMultiplies(negs, infos, wnafs));
        }
Esempio n. 2
0
        internal static ECPoint ImplShamirsTrickWNaf(ECEndomorphism endomorphism, ECPoint P, BigInteger k, BigInteger l)
        {
            bool negK = k.SignValue < 0, negL = l.SignValue < 0;

            k = k.Abs();
            l = l.Abs();

            int minWidth = WNafUtilities.GetWindowSize(System.Math.Max(k.BitLength, l.BitLength), 8);

            WNafPreCompInfo infoP = WNafUtilities.Precompute(P, minWidth, true);
            ECPoint         Q     = EndoUtilities.MapPoint(endomorphism, P);
            WNafPreCompInfo infoQ = WNafUtilities.PrecomputeWithPointMap(Q, endomorphism.PointMap, infoP, true);

            int widthP = System.Math.Min(8, infoP.Width);
            int widthQ = System.Math.Min(8, infoQ.Width);

            ECPoint[] preCompP    = negK ? infoP.PreCompNeg : infoP.PreComp;
            ECPoint[] preCompQ    = negL ? infoQ.PreCompNeg : infoQ.PreComp;
            ECPoint[] preCompNegP = negK ? infoP.PreComp : infoP.PreCompNeg;
            ECPoint[] preCompNegQ = negL ? infoQ.PreComp : infoQ.PreCompNeg;

            byte[] wnafP = WNafUtilities.GenerateWindowNaf(widthP, k);
            byte[] wnafQ = WNafUtilities.GenerateWindowNaf(widthQ, l);

            return(ImplShamirsTrickWNaf(preCompP, preCompNegP, wnafP, preCompQ, preCompNegQ, wnafQ));
        }