Decrypt.cs

        private static byte[] Decrypt(byte[] Data, int Offset)
        {
            MemoryStream memoryStream = new MemoryStream();
            int num = 0;
            byte b = 0;
            for (;;)
            {
                byte b2 = Data[num + Offset];
                if (b2 == 0)
                {
                    break;
                }
                if (num % 8 == 0)
                {
                    b = b2;
                }
                else if (((int)b & 1 << num % 8) == 0)
                {
                    memoryStream.WriteByte((byte)(b2 - (byte)1));
                }
                else
                {
                    memoryStream.WriteByte(b2);
                }
                num++;
            }
            return memoryStream.ToArray();
        }