Пример #1
0
        /// <summary>
        /// Reverse 64 bits of keystream into possible cipher states
        /// Variation mentioned in the paper. Somewhat optimized version
        /// </summary>
        /// <param name="ks2"></param>
        /// <param name="ks3"></param>
        /// <returns></returns>
        public static List <Crypto1State> LfsrRecovery64(uint ks2, uint ks3)
        {
            var oks       = new byte[32];
            var eks       = new byte[32];
            var hi        = new byte[32];
            var low       = 0u;
            var win       = 0u;
            var table     = new uint[1 << 16];
            var statelist = new List <Crypto1State>();

            for (var i = 30; i >= 0; i -= 2)
            {
                oks[i >> 1]        = ks2.BeBit(i);
                oks[16 + (i >> 1)] = ks3.BeBit(i);
            }
            for (var i = 31; i >= 0; i -= 2)
            {
                eks[i >> 1]        = ks2.BeBit(i);
                eks[16 + (i >> 1)] = ks3.BeBit(i);
            }


            for (var i = 0xfffffu; (int)i >= 0; i--)
            {
                if (Filter(i) != oks[0])
                {
                    continue;
                }

                var tail = 0;
                table[tail] = i;

                for (var j = 1; tail >= 0 && j < 29; j++)
                {
                    ExtendTableSimple(table, ref tail, oks[j]);
                }
                if (tail < 0)
                {
                    continue;
                }

                for (var j = 0; j < 19; ++j)
                {
                    low = low << 1 | EvenParity32(i & S1[j]);
                }
                for (var j = 0; j < 32; ++j)
                {
                    hi[j] = EvenParity32(i & T1[j]);
                }


                for (; tail >= 0; --tail)
                {
                    for (var j = 0; j < 3; j++)
                    {
                        table[tail]  = table[tail] << 1;
                        table[tail] |= EvenParity32((i & C1[j]) ^ (table[tail] & C2[j]));
                        if (Filter(table[tail]) != oks[29 + j])
                        {
                            goto continue2;
                        }
                    }

                    for (var j = 0; j < 19; j++)
                    {
                        win = win << 1 | EvenParity32(table[tail] & S2[j]);
                    }

                    win ^= low;
                    for (var j = 0; j < 32; ++j)
                    {
                        win = win << 1 ^ hi[j] ^ EvenParity32(table[tail] & T2[j]);
                        if (Filter(win) != eks[j])
                        {
                            goto continue2;
                        }
                    }

                    table[tail] = table[tail] << 1 | EvenParity32(LF_POLY_EVEN & table[tail]);
                    var s = new Crypto1State()
                    {
                        Odd  = table[tail] ^ EvenParity32(LF_POLY_ODD & win),
                        Even = win
                    };
                    statelist.Add(s);
                    continue2 :;
                }
            }
            return(statelist);
        }
Пример #2
0
 public Crypto1(Crypto1State state)
 {
     _state = state;
 }
Пример #3
0
 public Crapto1(Crypto1State state) : base(state)
 {
 }