Esempio n. 1
0
        /* convert from byte array to point */
        public static ECP FromBytes(sbyte[] b)
        {
            sbyte[] t = new sbyte[BIG.MODBYTES];
            BIG     p = new BIG(ROM.Modulus);

            for (int i = 0; i < BIG.MODBYTES; i++)
            {
                t[i] = b[i + 1];
            }

            BIG px = BIG.FromBytes(t);

            if (BIG.Comp(px, p) >= 0)
            {
                return(new ECP());
            }

            if (CURVETYPE == MONTGOMERY)
            {
                return(new ECP(px));
            }

            if (b[0] == 0x04)
            {
                for (int i = 0; i < BIG.MODBYTES; i++)
                {
                    t[i] = b[i + BIG.MODBYTES + 1];
                }

                BIG py = BIG.FromBytes(t);
                if (BIG.Comp(py, p) >= 0)
                {
                    return(new ECP());
                }

                return(new ECP(px, py));
            }

            if (b[0] == 0x02 || b[0] == 0x03)
            {
                return(new ECP(px, (int)(b[0] & 1)));
            }

            return(new ECP());
        }