BestHTTP.SecureProtocol.Org.BouncyCastle.Math.EC.Rfc7748.X25519Field.Mul C# (CSharp) Метод

        public static void Mul(int[] x, int[] y, int[] z)
        {
            int x0 = x[0], y0 = y[0];
            int x1 = x[1], y1 = y[1];
            int x2 = x[2], y2 = y[2];
            int x3 = x[3], y3 = y[3];
            int x4 = x[4], y4 = y[4];

            int u0 = x[5], v0 = y[5];
            int u1 = x[6], v1 = y[6];
            int u2 = x[7], v2 = y[7];
            int u3 = x[8], v3 = y[8];
            int u4 = x[9], v4 = y[9];

            long a0  = (long)x0 * y0;
            long a1  = (long)x0 * y1
                     + (long)x1 * y0;
            long a2  = (long)x0 * y2
                     + (long)x1 * y1
                     + (long)x2 * y0;
            long a3  = (long)x1 * y2
                     + (long)x2 * y1;
            a3     <<= 1;
            a3      += (long)x0 * y3
                     + (long)x3 * y0;
            long a4  = (long)x2 * y2;
            a4     <<= 1;
            a4      += (long)x0 * y4
                     + (long)x1 * y3
                     + (long)x3 * y1
                     + (long)x4 * y0;
            long a5  = (long)x1 * y4
                     + (long)x2 * y3
                     + (long)x3 * y2
                     + (long)x4 * y1;
            a5     <<= 1;
            long a6  = (long)x2 * y4
                     + (long)x4 * y2;
            a6     <<= 1;
            a6      += (long)x3 * y3;
            long a7  = (long)x3 * y4
                     + (long)x4 * y3;
            long a8  = (long)x4 * y4;
            a8     <<= 1;

            long b0  = (long)u0 * v0;
            long b1  = (long)u0 * v1
                     + (long)u1 * v0;
            long b2  = (long)u0 * v2
                     + (long)u1 * v1
                     + (long)u2 * v0;
            long b3  = (long)u1 * v2
                     + (long)u2 * v1;
            b3     <<= 1;
            b3      += (long)u0 * v3
                     + (long)u3 * v0;
            long b4  = (long)u2 * v2;
            b4     <<= 1;
            b4      += (long)u0 * v4
                     + (long)u1 * v3
                     + (long)u3 * v1
                     + (long)u4 * v0;
            long b5  = (long)u1 * v4
                     + (long)u2 * v3
                     + (long)u3 * v2
                     + (long)u4 * v1;
            //b5     <<= 1;
            long b6  = (long)u2 * v4
                     + (long)u4 * v2;
            b6     <<= 1;
            b6      += (long)u3 * v3;
            long b7  = (long)u3 * v4
                     + (long)u4 * v3;
            long b8  = (long)u4 * v4;
            //b8     <<= 1;

            a0 -= b5 * 76;
            a1 -= b6 * 38;
            a2 -= b7 * 38;
            a3 -= b8 * 76;

            a5 -= b0;
            a6 -= b1;
            a7 -= b2;
            a8 -= b3;
            //long a9 = -b4;

            x0 += u0; y0 += v0;
            x1 += u1; y1 += v1;
            x2 += u2; y2 += v2;
            x3 += u3; y3 += v3;
            x4 += u4; y4 += v4;

            long c0  = (long)x0 * y0;
            long c1  = (long)x0 * y1
                     + (long)x1 * y0;
            long c2  = (long)x0 * y2
                     + (long)x1 * y1
                     + (long)x2 * y0;
            long c3  = (long)x1 * y2
                     + (long)x2 * y1;
            c3     <<= 1;
            c3      += (long)x0 * y3
                     + (long)x3 * y0;
            long c4  = (long)x2 * y2;
            c4     <<= 1;
            c4      += (long)x0 * y4
                     + (long)x1 * y3
                     + (long)x3 * y1
                     + (long)x4 * y0;
            long c5  = (long)x1 * y4
                     + (long)x2 * y3
                     + (long)x3 * y2
                     + (long)x4 * y1;
            c5     <<= 1;
            long c6  = (long)x2 * y4
                     + (long)x4 * y2;
            c6     <<= 1;
            c6      += (long)x3 * y3;
            long c7  = (long)x3 * y4
                     + (long)x4 * y3;
            long c8  = (long)x4 * y4;
            c8     <<= 1;

            int z8, z9;
            long t;

            t        = a8 + (c3 - a3);
            z8       = (int)t & M26; t >>= 26;
            //t       += a9 + (c4 - a4);
            t       +=      (c4 - a4) - b4;
            //z9       = (int)t & M24; t >>= 24;
            //t        = a0 + (t + ((c5 - a5) << 1)) * 19;
            z9       = (int)t & M25; t >>= 25;
            t        = a0 + (t + c5 - a5) * 38;
            z[0]     = (int)t & M26; t >>= 26;
            t       += a1 + (c6 - a6) * 38;
            z[1]     = (int)t & M26; t >>= 26;
            t       += a2 + (c7 - a7) * 38;
            z[2]     = (int)t & M25; t >>= 25;
            t       += a3 + (c8 - a8) * 38;
            z[3]     = (int)t & M26; t >>= 26;
            //t       += a4 - a9 * 38;
            t       += a4 + b4 * 38;
            z[4]     = (int)t & M25; t >>= 25;
            t       += a5 + (c0 - a0);
            z[5]     = (int)t & M26; t >>= 26;
            t       += a6 + (c1 - a1);
            z[6]     = (int)t & M26; t >>= 26;
            t       += a7 + (c2 - a2);
            z[7]     = (int)t & M25; t >>= 25;
            t       += z8;
            z[8]     = (int)t & M26; t >>= 26;
            z[9]     = z9 + (int)t;
        }

        public static void ScalarMult(byte[] k, int kOff, byte[] u, int uOff, byte[] r, int rOff)
        {
            uint[] n = new uint[8];     DecodeScalar(k, kOff, n);

            int[] x1 = X25519Field.Create();        X25519Field.Decode(u, uOff, x1);
            int[] x2 = X25519Field.Create();        X25519Field.Copy(x1, 0, x2, 0);
            int[] z2 = X25519Field.Create();        z2[0] = 1;
            int[] x3 = X25519Field.Create();        x3[0] = 1;
            int[] z3 = X25519Field.Create();

            int[] t1 = X25519Field.Create();
            int[] t2 = X25519Field.Create();

            Debug.Assert(n[7] >> 30 == 1U);

            int bit = 254, swap = 1;

            do
            {
                X25519Field.Apm(x3, z3, t1, x3);
                X25519Field.Apm(x2, z2, z3, x2);
                X25519Field.Mul(t1, x2, t1);
                X25519Field.Mul(x3, z3, x3);
                X25519Field.Sqr(z3, z3);
                X25519Field.Sqr(x2, x2);

                X25519Field.Sub(z3, x2, t2);
                X25519Field.Mul(t2, C_A24, z2);
                X25519Field.Add(z2, x2, z2);
                X25519Field.Mul(z2, t2, z2);
                X25519Field.Mul(x2, z3, x2);

                X25519Field.Apm(t1, x3, x3, z3);
                X25519Field.Sqr(x3, x3);
                X25519Field.Sqr(z3, z3);
                X25519Field.Mul(z3, x1, z3);

                --bit;

                int word = bit >> 5, shift = bit & 0x1F;
                int kt = (int)(n[word] >> shift) & 1;
                swap ^= kt;
                X25519Field.CSwap(swap, x2, x3);
                X25519Field.CSwap(swap, z2, z3);
                swap = kt;
            }while (bit >= 3);

            Debug.Assert(swap == 0);

            for (int i = 0; i < 3; ++i)
            {
                PointDouble(x2, z2);
            }

            X25519Field.Inv(z2, z2);
            X25519Field.Mul(x2, z2, x2);

            X25519Field.Normalize(x2);
            X25519Field.Encode(x2, r, rOff);
        }