Example #1
0
        public static void Precompute()
        {
            if (precompBase != null)
            {
                return;
            }

            PointExt p = new PointExt();

            X448Field.Copy(B_x, 0, p.x, 0);
            X448Field.Copy(B_y, 0, p.y, 0);
            PointExtendXY(p);

            precompBaseTable = PointPrecompVar(p, 1 << (WnafWidthBase - 2));

            precompBase = new uint[PrecompBlocks * PrecompPoints * 2 * X448Field.Size];

            int off = 0;

            for (int b = 0; b < PrecompBlocks; ++b)
            {
                PointExt[] ds = new PointExt[PrecompTeeth];

                PointExt sum = new PointExt();
                PointSetNeutral(sum);

                for (int t = 0; t < PrecompTeeth; ++t)
                {
                    PointAddVar(true, p, sum);
                    PointDouble(p);

                    ds[t] = PointCopy(p);

                    for (int s = 1; s < PrecompSpacing; ++s)
                    {
                        PointDouble(p);
                    }
                }

                PointExt[] points = new PointExt[PrecompPoints];
                int        k      = 0;
                points[k++] = sum;

                for (int t = 0; t < (PrecompTeeth - 1); ++t)
                {
                    int size = 1 << t;
                    for (int j = 0; j < size; ++j, ++k)
                    {
                        points[k] = PointCopy(points[k - size]);
                        PointAddVar(false, ds[t], points[k]);
                    }
                }

                Debug.Assert(k == PrecompPoints);

                for (int i = 0; i < PrecompPoints; ++i)
                {
                    PointExt q = points[i];
                    // TODO[ed448] Batch inversion
                    X448Field.Inv(q.z, q.z);
                    X448Field.Mul(q.x, q.z, q.x);
                    X448Field.Mul(q.y, q.z, q.y);

                    //                X448Field.Normalize(q.x);
                    //                X448Field.Normalize(q.y);

                    X448Field.Copy(q.x, 0, precompBase, off);   off += X448Field.Size;
                    X448Field.Copy(q.y, 0, precompBase, off);   off += X448Field.Size;
                }
            }

            Debug.Assert(off == precompBase.Length);
        }