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TestProject.zip
다운로드

▶ SteganographyState.cs

namespace TestProject
{
    /// <summary>
    /// 스테가노그래피 상태
    /// </summary>
    public enum SteganographyState
    {
        /// <summary>
        /// HIDING
        /// </summary>
        HIDING,

        /// <summary>
        /// FILLING_WITH_ZEROS
        /// </summary>
        FILLING_WITH_ZEROS
    };
}

 

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▶ SteganographyHelper.cs

using System.Drawing;

namespace TestProject
{
    /// <summary>
    /// 스테가노그래피 헬퍼
    /// </summary>
    public static class SteganographyHelper
    {
        //////////////////////////////////////////////////////////////////////////////////////////////////// Method
        ////////////////////////////////////////////////////////////////////////////////////////// Static
        //////////////////////////////////////////////////////////////////////////////// Public

        #region 비트맵 구하기 - GetBitmap(sourceText, sourceBitmap)

        /// <summary>
        /// 비트맵 구하기
        /// </summary>
        /// <param name="sourceText">소스 텍스트</param>
        /// <param name="sourceBitmap">소스 비트맵</param>
        /// <returns>비트맵</returns>
        public static Bitmap GetBitmap(string sourceText, Bitmap sourceBitmap)
        {
            SteganographyState state = SteganographyState.HIDING;

            int  characterIndex = 0;
            int  characterValue = 0;
            long colorUnitIndex = 0;
            int  zeros          = 0;
            int  red            = 0;
            int  green          = 0;
            int  blue           = 0;

            Bitmap targetBitmap = sourceBitmap.Clone() as Bitmap;

            for(int y = 0; y < sourceBitmap.Height; y++)
            {
                for(int x = 0; x < sourceBitmap.Width; x++)
                {
                    Color pixel = sourceBitmap.GetPixel(x, y);

                    pixel = Color.FromArgb(pixel.R - pixel.R % 2, pixel.G - pixel.G % 2, pixel.B - pixel.B % 2);

                    red   = pixel.R;
                    green = pixel.G;
                    blue  = pixel.B;

                    for(int i = 0; i < 3; i++)
                    {
                        if(colorUnitIndex % 8 == 0)
                        {
                            if(zeros == 8)
                            {
                                if((colorUnitIndex - 1) % 3 < 2)
                                {
                                    targetBitmap.SetPixel(x, y, Color.FromArgb(red, green, blue));
                                }

                                return targetBitmap;
                            }

                            if(characterIndex >= sourceText.Length)
                            {
                                state = SteganographyState.FILLING_WITH_ZEROS;
                            }
                            else
                            {
                                characterValue = sourceText[characterIndex++];
                            }
                        }

                        switch(colorUnitIndex % 3)
                        {
                            case 0 :
                            {
                                if(state == SteganographyState.HIDING)
                                {
                                    red += characterValue % 2;

                                    characterValue /= 2;
                                }

                                break;
                            }
                            case 1 :
                            {
                                if(state == SteganographyState.HIDING)
                                {
                                    green += characterValue % 2;

                                    characterValue /= 2;
                                }

                                break;
                            }
                            case 2 :
                            {
                                if(state == SteganographyState.HIDING)
                                {
                                    blue += characterValue % 2;

                                    characterValue /= 2;
                                }

                                targetBitmap.SetPixel(x, y, Color.FromArgb(red, green, blue));

                                break;
                            }
                        }

                        colorUnitIndex++;

                        if(state == SteganographyState.FILLING_WITH_ZEROS)
                        {
                            zeros++;
                        }
                    }
                }
            }

            return targetBitmap;
        }

        #endregion
        #region 텍스트 구하기 - GetText(sourceBitmap)

        /// <summary>
        /// 텍스트 구하기
        /// </summary>
        /// <param name="sourceBitmap">소스 비트맵</param>
        /// <returns>텍스트</returns>
        public static string GetText(Bitmap sourceBitmap)
        {
            int    colorUnitIndex = 0;
            int    characterValue = 0;
            string targetText     = string.Empty;

            for(int y = 0; y < sourceBitmap.Height; y++)
            {
                for(int x = 0; x < sourceBitmap.Width; x++)
                {
                    Color pixel = sourceBitmap.GetPixel(x, y);

                    for(int i = 0; i < 3; i++)
                    {
                        switch(colorUnitIndex % 3)
                        {
                            case 0 :
                            {
                                characterValue = characterValue * 2 + pixel.R % 2;

                                break;
                            }
                            case 1 :
                            {
                                characterValue = characterValue * 2 + pixel.G % 2;

                                break;
                            }
                            case 2 :
                            {
                                characterValue = characterValue * 2 + pixel.B % 2;

                                break;
                            }
                        }

                        colorUnitIndex++;

                        if(colorUnitIndex % 8 == 0)
                        {
                            characterValue = ReverseBits(characterValue);

                            if(characterValue == 0)
                            {
                                return targetText;
                            }

                            char character = (char)characterValue;

                            targetText += character.ToString();
                        }
                    }
                }
            }

            return targetText;
        }

        #endregion

        //////////////////////////////////////////////////////////////////////////////// Private

        #region 비트 반전하기 - ReverseBits(sourceValue)

        /// <summary>
        /// 비트 반전하기
        /// </summary>
        /// <param name="sourceValue">소스 값</param>
        /// <returns>비트 반전 값</returns>
        public static int ReverseBits(int sourceValue)
        {
            int targetValue = 0;

            for(int i = 0; i < 8; i++)
            {
                targetValue = targetValue * 2 + sourceValue % 2;

                sourceValue /= 2;
            }

            return targetValue;
        }

        #endregion
    }
}

 

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▶ AESHelper.cs

using System;
using System.IO;
using System.Text;
using System.Security.Cryptography;

namespace TestProject
{
    /// <summary>
    /// AES 헬퍼
    /// </summary>
    public static class AESHelper
    {
        //////////////////////////////////////////////////////////////////////////////////////////////////// Field
        ////////////////////////////////////////////////////////////////////////////////////////// Static
        //////////////////////////////////////////////////////////////////////////////// Field

        #region Field

        /// <summary>
        /// SALT 배열
        /// </summary>
        private static byte[] _saltArray = Encoding.ASCII.GetBytes("123456789abcdefghijkllmn");

        #endregion

        //////////////////////////////////////////////////////////////////////////////////////////////////// Method
        ////////////////////////////////////////////////////////////////////////////////////////// Static
        //////////////////////////////////////////////////////////////////////////////// Public

        #region 암호화 하기 - Encrypt(sourceText, key)

        /// <summary>
        /// 암호화 하기
        /// </summary>
        /// <param name="sourceText">소스 텍스트</param>
        /// <param name="key">키</param>
        /// <returns>암호화 텍스트</returns>
        public static string Encrypt(string sourceText, string key)
        {
            string          targetText      = null;
            RijndaelManaged rijndaelManaged = null;

            try
            {
                Rfc2898DeriveBytes rfc2898DeriveBytes = new Rfc2898DeriveBytes(key, _saltArray);

                rijndaelManaged = new RijndaelManaged();

                rijndaelManaged.Key = rfc2898DeriveBytes.GetBytes(rijndaelManaged.KeySize / 8);

                ICryptoTransform cryptoTransform = rijndaelManaged.CreateEncryptor(rijndaelManaged.Key, rijndaelManaged.IV);

                using(MemoryStream memoryStream = new MemoryStream())
                {
                    memoryStream.Write(BitConverter.GetBytes(rijndaelManaged.IV.Length), 0, sizeof(int));

                    memoryStream.Write(rijndaelManaged.IV, 0, rijndaelManaged.IV.Length);

                    using(CryptoStream cryptoStream = new CryptoStream(memoryStream, cryptoTransform, CryptoStreamMode.Write))
                    {
                        using(StreamWriter streamWriter = new StreamWriter(cryptoStream))
                        {
                            streamWriter.Write(sourceText);
                        }
                    }

                    targetText = Convert.ToBase64String(memoryStream.ToArray());
                }
            }
            finally
            {
                if(rijndaelManaged != null)
                {
                    rijndaelManaged.Clear();
                }
            }

            return targetText;
        }

        #endregion
        #region 복호화 하기 - Decrypt(sourceText, key)

        /// <summary>
        /// 복호화 하기
        /// </summary>
        /// <param name="sourceText">소스 텍스트</param>
        /// <param name="key">키</param>
        /// <returns>복호화 텍스트</returns>
        public static string Decrypt(string sourceText, string key)
        {
            RijndaelManaged rijndaelManaged = null;
            string          targetText      = null;

            try
            {
                Rfc2898DeriveBytes rfc2898DeriveBytes = new Rfc2898DeriveBytes(key, _saltArray);

                byte[] sourceByteArray = Convert.FromBase64String(sourceText);

                using(MemoryStream memoryStream = new MemoryStream(sourceByteArray))
                {
                    rijndaelManaged = new RijndaelManaged();

                    rijndaelManaged.Key = rfc2898DeriveBytes.GetBytes(rijndaelManaged.KeySize / 8);
                    rijndaelManaged.IV  = ReadByteArray(memoryStream);

                    ICryptoTransform dryptoTransform = rijndaelManaged.CreateDecryptor(rijndaelManaged.Key, rijndaelManaged.IV);

                    using(CryptoStream cryptoStream = new CryptoStream(memoryStream, dryptoTransform, CryptoStreamMode.Read))
                    {
                        using(StreamReader streamReader = new StreamReader(cryptoStream))
                        {
                            targetText = streamReader.ReadToEnd();
                        }
                    }
                }
            }
            finally
            {
                if(rijndaelManaged != null)
                {
                    rijndaelManaged.Clear();
                }
            }

            return targetText;
        }

        #endregion

        //////////////////////////////////////////////////////////////////////////////// Private

        #region 바이트 배열 읽기 - ReadByteArray(stream)

        /// <summary>
        /// 바이트 배열 읽기
        /// </summary>
        /// <param name="stream">스트림</param>
        /// <returns>바이트 배열</returns>
        private static byte[] ReadByteArray(Stream stream)
        {
            byte[] rawLengthArray = new byte[sizeof(int)];

            if(stream.Read(rawLengthArray, 0, rawLengthArray.Length) != rawLengthArray.Length)
            {
                throw new SystemException();
            }

            byte[] bufferArray = new byte[BitConverter.ToInt32(rawLengthArray, 0)];

            if(stream.Read(bufferArray, 0, bufferArray.Length) != bufferArray.Length)
            {
                throw new SystemException();
            }

            return bufferArray;
        }

        #endregion
    }
}

 

▶ MainForm.cs

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Windows.Forms;

namespace TestProject
{
    /// <summary>
    /// 메인 폼
    /// </summary>
    public partial class MainForm : Form
    {
        //////////////////////////////////////////////////////////////////////////////////////////////////// Field
        ////////////////////////////////////////////////////////////////////////////////////////// Private

        #region Field

        /// <summary>
        /// 소스 비트맵
        /// </summary>
        private Bitmap sourceBitmap = null;

        #endregion

        //////////////////////////////////////////////////////////////////////////////////////////////////// Constructor
        ////////////////////////////////////////////////////////////////////////////////////////// Public

        #region 생성자 - MainForm()

        /// <summary>
        /// 생성자
        /// </summary>
        public MainForm()
        {
            InitializeComponent();
        }

        #endregion

        //////////////////////////////////////////////////////////////////////////////////////////////////// Method
        ////////////////////////////////////////////////////////////////////////////////////////// Private
        //////////////////////////////////////////////////////////////////////////////// Event

        #region 열기 메뉴 항목 클릭시 처리하기 - openMenuItem_Click(sender, e)

        /// <summary>
        /// 열기 메뉴 항목 클릭시 처리하기
        /// </summary>
        /// <param name="sender">이벤트 발생자</param>
        /// <param name="e">이벤트 인자</param>
        private void openMenuItem_Click(object sender, EventArgs e)
        {
            if(this.openFileDialog.ShowDialog() == DialogResult.OK)
            {
                this.pictureBox.Image = Image.FromFile(this.openFileDialog.FileName);

                this.encryptButton.Enabled = true;
                this.decryptButton.Enabled = true;
            }
        }

        #endregion
        #region 종료 메뉴 항목 클릭시 처리하기 - exitMenuItem_Click(sender, e)

        /// <summary>
        /// 종료 메뉴 항목 클릭시 처리하기
        /// </summary>
        /// <param name="sender">이벤트 발생자</param>
        /// <param name="e">이벤트 인자</param>
        private void exitMenuItem_Click(object sender, EventArgs e)
        {
            Close();
        }

        #endregion

        #region 암호화 버튼 클릭시 처리하기 - encryptButton_Click(sender, e)

        /// <summary>
        /// 암호화 버튼 클릭시 처리하기
        /// </summary>
        /// <param name="sender">이벤트 발생자</param>
        /// <param name="e">이벤트 인자</param>
        private void encryptButton_Click(object sender, EventArgs e)
        {
            if(this.pictureBox.Image == null)
            {
                MessageBox.Show(this, "이미지 파일을 선택해 주시기 바랍니다.", "INFORMATION", MessageBoxButtons.OK, MessageBoxIcon.Information);

                return;
            }

            this.sourceBitmap = this.pictureBox.Image as Bitmap;

            string sourceText = this.textBox.Text;

            if(string.IsNullOrWhiteSpace(sourceText))
            {
                MessageBox.Show(this, "텍스트를 입력해 주시기 바랍니다.", "INFORMATION", MessageBoxButtons.OK, MessageBoxIcon.Information);

                this.textBox.Focus();

                return;
            }

            if(this.keyTextBox.Text.Length < 8)
            {
                MessageBox.Show(this, "비밀키는 8자리 이상 입력해 주시기 바랍니다.", "INFORMATION", MessageBoxButtons.OK, MessageBoxIcon.Information);

                this.keyTextBox.Focus();

                return;
            }
            else
            {
                sourceText = AESHelper.Encrypt(sourceText, this.keyTextBox.Text);
            }

            sourceBitmap = SteganographyHelper.GetBitmap(sourceText, sourceBitmap);

            if(this.saveFileDialog.ShowDialog() == DialogResult.OK)
            {
                switch(this.saveFileDialog.FilterIndex)
                {
                    case 0 :
                    {
                        this.sourceBitmap.Save(this.saveFileDialog.FileName, ImageFormat.Png);

                        break;
                    }
                    case 1 :
                    {
                        this.sourceBitmap.Save(this.saveFileDialog.FileName, ImageFormat.Bmp);

                        break;
                    }
                }
            }

            ClearControlData();
        }

        #endregion
        #region 복호화 버튼 클릭시 처리하기 - decryptButton_Click(sender, e)

        /// <summary>
        /// 복호화 버튼 클릭시 처리하기
        /// </summary>
        /// <param name="sender">이벤트 발생자</param>
        /// <param name="e">이벤트 인자</param>
        private void decryptButton_Click(object sender, EventArgs e)
        {
            this.sourceBitmap = this.pictureBox.Image as Bitmap;

            string text = SteganographyHelper.GetText(sourceBitmap);

            try
            {
                text = AESHelper.Decrypt(text, this.keyTextBox.Text);
            }
            catch
            {
                MessageBox.Show(this, "비밀키가 일치하지 않습니다.", "INFORMATION", MessageBoxButtons.OK, MessageBoxIcon.Information);

                this.keyTextBox.Focus();

                return;
            }

            this.textBox.Text = text;
        }

        #endregion

        //////////////////////////////////////////////////////////////////////////////// Function

        #region 컨트롤 데이터 지우기 - ClearControlData()

        /// <summary>
        /// 컨트롤 데이터 지우기
        /// </summary>
        private void ClearControlData()
        {
            this.pictureBox.Image = null;

            this.textBox.Clear();

            this.keyTextBox.Clear();

            this.encryptButton.Enabled = false;
            this.decryptButton.Enabled = false;
        }

        #endregion
    }
}
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