LSB

using System;
using System.Net.Mime;
using System.Text;
using ImageMagick;

namespace Lab2_4
{
    public class LSB
    {
        private readonly ushort ONE_BYTE = 8;

        public bool EncodeTextToImage(string text, string path)
        {
            int length = Math.Min(text.Length, 255);
            MagickImage image = null;
            try
            {
                image = new MagickImage(path);
            }
            catch
            {
                return false;
            }

            for (int i = 0; i < ONE_BYTE; i++)
            {
                var pixels = image.GetPixels();
                var color = pixels[i, image.Height - 1].ToColor();
                byte red = color.R;

                red = Convert.ToByte( (red & 254) | ((length & (1 << i)) > 0 ? 1 : 0) );
                var newColors = new MagickColor
                {
                    A = color.A,
                    B = color.B,
                    G = color.G,
                    K = color.K,
                    R = red
                };
                pixels.SetPixel(new Pixel(i, image.Height - 1, newColors.ToByteArray()));
            }

            int x = ONE_BYTE;
            int y = image.Height - 1;
            for (int i = 0; i < length; i++)
            {
                int character = text[i];
                for (int j = 0; j < ONE_BYTE; j++)
                {
                    if (x >= image.Width)
                    {
                        y--;
                        x = 0;
                    }
                    var pixels = image.GetPixels();
                    var color = pixels[x, y].ToColor();
                    byte red = color.R;

                    red = Convert.ToByte( (red & 254) | ((character & (1 << i)) > 0 ? 1 : 0) );
                    var newColors = new MagickColor
                    {
                        A = color.A,
                        B = color.B,
                        G = color.G,
                        K = color.K,
                        R = red
                    };
                    pixels.SetPixel(new Pixel(i, image.Height - 1, newColors.ToByteArray()));
                    x++;
                }
            }

            string[] result_path = path.Split('.');
            result_path[0] = string.Concat(result_path[0], "_resultEncrypting.");
            try
            {
                image.Write(string.Concat(result_path));
            }
            catch
            {
                return false;
            }
            return true;
        }

        public string DecodeTextFromImage(string path)
        {
            var decodedText = string.Empty;
            int length = 0;
            MagickImage image = null;
            try
            {
                image = new MagickImage(path);
            }
            catch
            {
                return null;
            }

            for (int i = 0; i < ONE_BYTE; i++)
            {
                var color = image.GetPixels()[i, image.Height - 1].ToColor();

                length = length | ((color.R & 1) << 1);
            }

            int x = ONE_BYTE;
            int y = image.Height - 1;
            for (int i = 0; i < length; i++)
            {
                int character = 0;
                for (int j = 0; j < ONE_BYTE; j++)
                {
                    if (x >= image.Width)
                    {
                        y--;
                        x = 0;
                    }
                    var color = image.GetPixels()[i, image.Height - 1].ToColor();
                    int r = color.R;

                    character |= ((r & 1) << j);
                }

                decodedText += Convert.ToChar(character);
            }

            return decodedText;
        }
    }
}