AES 256 file encryption key mistake

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Hey guys;
ı have a project about AES256 file encryption.The promlem is that i can't use the symmetric key in my alghoritm.When I encrypted a file,i'm using a password also it should be same password to decrypt a file.But when i give different password to decrypt the .jpeg file (or anyone) again the system is encrypted it.I wanna use symmetric key to do this action how can i do dat?

FOR INSTANCE:
Choose a file-->select encrypt-->password(1234);
choose a file-->select decrypt-->password(asd);
P.S : i wanna do decryption with first password

C#

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;

namespace AES256
{
    public partial class Form1 : Form
    {
        public const int MAX_BLOCK_LENGTH = 16;
        public const int MAX_KEY_LENGTH = 16;

        private enum ErrorID
        {
            NullFilePath = 0,
            NUllFileSave,
            NullPWD,
            OtherError,
            Success,
        };

        private string[] ErrorString = new string[]{
            "No File be Selected",
            "No File be Saved",
            "No Password input",
            "Other Error",
            "OK"};

        private enum Direction
        {
            Encrypt = 0,
            Decrypt,
        };


        private KeySize ekeySize;
        private BlockSize eblockSize;
        private Direction eDirEnDe;

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            ekeySize = KeySize.Bits256;
            eblockSize = BlockSize.Bits256;
            eDirEnDe = Direction.Encrypt;
        }

        private void EnOption_CheckedChanged_1(object sender, EventArgs e)
        {
            EnDeCode.Text = this.EnOption.Text;
            TxtFilePath.Text = "";
            TxtFileSave.Text = "";
            eDirEnDe = Direction.Encrypt;
        }

        private void EnDeCode_Click(object sender, EventArgs e)
        {
            ErrorID errorID = CheckParam();
            if (ErrorID.Success != errorID)
            {
                string errorString = GetErrorString(errorID);
                MessageBox.Show(errorString, "Rijndael");
                return;
            }
            //get param
            string cOpenFile = TxtFilePath.Text;
            string cSaveFile = TxtFileSave.Text;
            string cPassword = txtPwd.Text;
            //check param successfully
            if (Direction.Encrypt == eDirEnDe)
            {
                Boolean bValue = Encrypt(cOpenFile, cSaveFile, cPassword);
                if (false == bValue)
                {
                    MessageBox.Show("Encrypt Fail", "Rijndael");
                    return;
                }

            }
            else
            {
                Boolean bValue = Decrypt(cOpenFile, cSaveFile, cPassword);
                if (false == bValue)
                {
                    MessageBox.Show("Decrypt Fail", "Rijndael");
                    return;
                }
            }          
        }

        private void DeOption_CheckedChanged(object sender, EventArgs e)
        {
            EnDeCode.Text = this.DeOption.Text;
            TxtFilePath.Text = "";
            TxtFileSave.Text = "";
            eDirEnDe = Direction.Decrypt;
        }

        private void Browse_Click(object sender, EventArgs e)
        {
            OpenFileDialog openFileDialog = new OpenFileDialog();
            openFileDialog.Title = "Rijndael";
            if (eDirEnDe == Direction.Encrypt)
            {
                openFileDialog.Filter = "All File|*.*";
                if (DialogResult.OK == openFileDialog.ShowDialog())
                {
                    string fName = openFileDialog.FileName;
                    TxtFilePath.Text = fName;
                    TxtFileSave.Text = fName + ".aes";
                }
            }
            else
            {
                openFileDialog.Filter = "AES File|*.aes";
                if (DialogResult.OK == openFileDialog.ShowDialog())
                {
                    string fName = openFileDialog.FileName;
                    TxtFilePath.Text = fName;
                    int iLastIndex = fName.LastIndexOf(".");
                    string cOrigalName = fName.Substring(0, iLastIndex);
                    TxtFileSave.Text = cOrigalName;
                }
            }
        }

        private void Save_Click(object sender, EventArgs e)
        {
            // Displays a SaveFileDialog so the user can save the Image
            // assigned to Button2.
            SaveFileDialog saveFileDialog = new SaveFileDialog();
            saveFileDialog.Title = "Rijndael";

            if (eDirEnDe == Direction.Encrypt)
            {
                saveFileDialog.Filter = "AES File|*.aes";
                DialogResult dialogResult = saveFileDialog.ShowDialog();
                // If the file name is not an empty string open it for saving.
                string fName = saveFileDialog.FileName;
                if (("" != fName) && (dialogResult == DialogResult.OK))
                {
                    TxtFileSave.Text = fName;
                }
            }
            else
            {
                saveFileDialog.Filter = "All File|*.*";
                DialogResult dialogResult = saveFileDialog.ShowDialog();
                // If the file name is not an empty string open it for saving.
                string fName = saveFileDialog.FileName;
                if (("" != fName) && (dialogResult == DialogResult.OK))
                {
                    TxtFileSave.Text = fName;
                }
            }
        }

        private ErrorID CheckParam()
        {
            if ("" == TxtFilePath.Text)
            {
                return ErrorID.NullFilePath;
            }

            if ("" == TxtFileSave.Text)
            {
                return ErrorID.NUllFileSave;
            }

            if ("" == txtPwd.Text)
            {
                return ErrorID.NullPWD;
            }

            return ErrorID.Success;
        }

        private string GetErrorString(ErrorID errorID)
        {
            int iIndex = (int)(errorID);

            return ErrorString[iIndex];
        }

        private Boolean Encrypt(string cOpenFile, string cSaveFile, string cPassword)
        {
            //check param
            if (("" == cOpenFile) ||
                ("" == cSaveFile) ||
                ("" == cPassword))
            {
                return false;
            }

            if (false == File.Exists(cOpenFile))
            {
                return false;
            }

            while (true == File.Exists(cSaveFile))
            {
                cSaveFile = Rename(cSaveFile);
            }

            byte[] plainText = new byte[MAX_BLOCK_LENGTH];
            byte[] cipherText = new byte[MAX_BLOCK_LENGTH];
            byte[] bzkey = new byte[MAX_KEY_LENGTH];

            //get password
            bzkey = Encoding.Unicode.GetBytes(cPassword);

            //get bytes from file
            FileStream fileStream = new FileStream(cOpenFile, FileMode.Open);
            fileStream.Seek(0, SeekOrigin.Begin);

            //get the file stream for save 
            FileStream saveStream = new FileStream(cSaveFile, FileMode.Append);

            //set length of the file
            long lFileLength = fileStream.Length;
            //set position of the file
            long lPostion = fileStream.Position;

            //Read byte and Encrypt
            while (lPostion < lFileLength)
            {
                //Initialize  the buffer
                Initialize(plainText, MAX_BLOCK_LENGTH);

                long lHasRead = fileStream.Read(plainText, 0, MAX_BLOCK_LENGTH);
                if (0 >= lHasRead)
                {
                    break;
                }
                //set current cursor position
                lPostion = fileStream.Position;

                //Encrypt
                Aes aes = new Aes(ekeySize, bzkey, eblockSize);

                //Initialize  the buffer
                Initialize(cipherText, MAX_BLOCK_LENGTH);

                aes.Cipher(plainText, cipherText);
                saveStream.Write(cipherText, 0, MAX_BLOCK_LENGTH);
            }

            saveStream.Close();
            fileStream.Close();
            return true;
        }

        private Boolean Decrypt(string cOpenFile, string cSaveFile, string cPassword)
        {
            //check param
            if (("" == cOpenFile) ||
                ("" == cSaveFile) ||
                ("" == cPassword))
            {
                return false;
            }

            if (0 > cOpenFile.LastIndexOf(".aes"))
            {
                return false;
            }

            if (false == File.Exists(cOpenFile))
            {
                return false;
            }

            while (true == File.Exists(cSaveFile))
            {
                cSaveFile = Rename(cSaveFile);
            }

            byte[] plainText = new byte[MAX_BLOCK_LENGTH];
            byte[] cipherText = new byte[MAX_BLOCK_LENGTH];
            byte[] bzkey = new byte[MAX_KEY_LENGTH];

            //get password
            bzkey = Encoding.Unicode.GetBytes(cPassword);
     
            //get bytes from file
            FileStream fileStream = new FileStream(cOpenFile, FileMode.Open);
            fileStream.Seek(0, SeekOrigin.Begin);

            //get the file stream for save 
            FileStream saveStream = new FileStream(cSaveFile, FileMode.Append);

            //set length of the file
            long lFileLength = fileStream.Length;
            //set position of the file
            long lPostion = fileStream.Position;

            //Read byte and Decrypt
            while (lPostion < lFileLength)
            {
                //Initialize  the buffer
                Initialize(plainText, MAX_BLOCK_LENGTH);

                long lHasRead = fileStream.Read(plainText, 0, MAX_BLOCK_LENGTH);
                if (0 >= lHasRead)
                {
                    break;
                }
                //set current cursor position
                lPostion = fileStream.Position;

                //Encrypt
                Aes aes = new Aes(ekeySize, bzkey, eblockSize);

                //Initialize  the buffer
                Initialize(cipherText, MAX_BLOCK_LENGTH);
                //Decrypt
                aes.InvCipher(plainText, cipherText);
                saveStream.Write(cipherText, 0, MAX_BLOCK_LENGTH);
            }
            
           
            saveStream.Close();
            fileStream.Close();

            return true;
        }

        private void Initialize(byte[] pByte, int iLength)
        {
            int iIndex = 0;
            for (iIndex = 0; iIndex < iLength; iIndex++)
            {
                pByte[iIndex] = 0;
            }
        }

        private string Rename(string cName)
        {
            string cFileName = cName;
            string cExtentName = "";
            int iIndex = cName.IndexOf(".");
            if (iIndex > 0)
            {
                cFileName = cName.Substring(0, iIndex);
                cExtentName = cName.Substring(iIndex);
            }
            cFileName += "aes";
            cFileName += cExtentName;
            return cFileName;
        }

    }
}


namespace AES256
{
    public enum KeySize { 
        Bits128 = 0, 
        Bits192, 
        Bits256=0 
    };  // key size, in bits, for construtor
    
    public enum BlockSize { 
        Bits128 = 0, 
        Bits192, 
        Bits256 =0
    };

    class Aes
    {
        private int Nb;         // block size in 32-bit words.  Always 4 for AES.  (128 bits).
        private int Nk;         // key size in 32-bit words.  4, 6, 8.  (128, 192, 256 bits).
        private int Nr;         // number of rounds. 10, 12, 14.

        private byte[] key;     // the seed key. size will be 4 * keySize from ctor.
        private byte[,] Sbox;   // Substitution box
        private byte[,] iSbox;  // inverse Substitution box 
        private byte[,] w;      // key schedule array. 
        private byte[,] Rcon;   // Round constants.
        private byte[,] State;  // State matrix
        private int[,] NbNkNr;

        /// <summary>
        /// 
        /// </summary>
        /// <param name="keySize"></param>
        /// <param name="keyBytes"></param>
        /// <param name="blockSize"></param>
        /// <returns></returns>
        public Aes(KeySize keySize, byte[] keyBytes, BlockSize blockSize)
        {

            BuildNaNkNr();

            SetNbNkNr(keySize, blockSize);

            this.key = new byte[this.Nk * 4];  // 16, 24, 32 bytes
            //keyBytes.CopyTo(this.key, 0);

            BuildSbox();
            BuildInvSbox();
            BuildRcon();
            KeyExpansion();  // expand the seed key into a key schedule and store in w

        }  // Aes constructor

        public void Cipher(byte[] input, byte[] output)  // encipher 16-bit input
        {
            // state = input
            this.State = new byte[4, Nb];  // always [4,4]
            for (int i = 0; i < (4 * Nb); ++i)
            {
                this.State[i % 4, i / 4] = input[i];
            }

            AddRoundKey(0);

            for (int round = 1; round <= (Nr - 1); ++round)  // main round loop
            {
                SubBytes();
                ShiftRows();
                MixColumns();
                AddRoundKey(round);
            }  // main round loop

            SubBytes();
            ShiftRows();
            AddRoundKey(Nr);

            for (int i = 0; i < (4 * Nb); ++i)
            {
                output[i] = this.State[i % 4, i / 4];
            }

        }  // Cipher()

        public void InvCipher(byte[] input, byte[] output)  // decipher 16-bit input
        {
            // state = input
            this.State = new byte[4, Nb];  // always [4,4]
            for (int i = 0; i < (4 * Nb); ++i)
            {
                this.State[i % 4, i / 4] = input[i];
            }

            AddRoundKey(Nr);

            for (int round = Nr - 1; round >= 1; --round)  // main round loop
            {
                InvShiftRows();
                InvSubBytes();
                AddRoundKey(round);
                InvMixColumns();
            }  // end main round loop for InvCipher

            InvShiftRows();
            InvSubBytes();
            AddRoundKey(0);

            // output = state
            for (int i = 0; i < (4 * Nb); ++i)
            {
                output[i] = this.State[i % 4, i / 4];
            }

        }  // InvCipher()

        //BuildNaNkNr
        private void BuildNaNkNr()
        {
            this.NbNkNr = new int[3, 3]{
                    /*0     1       2*/
            /*0*/   {10,12,14},
            /*1*/   {12,12,14},
            /*2*/   {14,14,14}};
        }//BuildNaNkNr

        /// <summary>
        /// 
        /// </summary>
        /// <param name="keySize"></param>
        /// <param name="blockSize"></param>
        /// <returns>void</returns>
        private void SetNbNkNr(KeySize keySize, BlockSize blockSize)
        {
            int x = (int)(keySize);
            int y = (int)(blockSize);

            this.Nr = NbNkNr[x, y];

            if (KeySize.Bits128 == keySize)
            {
                this.Nk = 4;
            }
            else if (KeySize.Bits128 == keySize)
            {
                this.Nk = 6;
            }
            else if (KeySize.Bits256 == keySize)
            {
                this.Nk = 8;
            }

            if (BlockSize.Bits128 == blockSize)
            {
                this.Nb = 4;
            }
            else if (BlockSize.Bits128 == blockSize)
            {
                this.Nb = 6;
            }
            else if (BlockSize.Bits256 == blockSize)
            {
                this.Nb = 8;
            }

        }  // SetNbNkNr()

        /// <summary>
        /// 
        /// </summary>
        /// <returns></returns>
        private void BuildSbox()
        {
            this.Sbox = new byte[16, 16] {  // populate the Sbox matrix
    /* 0     1     2     3     4     5     6     7     8     9     a     b     c     d     e     f */
    /*0*/  {0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76},
    /*1*/  {0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0},
    /*2*/  {0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15},
    /*3*/  {0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75},
    /*4*/  {0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84},
    /*5*/  {0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf},
    /*6*/  {0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8},
    /*7*/  {0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2},
    /*8*/  {0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73},
    /*9*/  {0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb},
    /*a*/  {0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79},
    /*b*/  {0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08},
    /*c*/  {0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a},
    /*d*/  {0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e},
    /*e*/  {0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf},
    /*f*/  {0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16} };

        }  // BuildSbox() 

        /// <summary>
        /// 
        /// </summary>
        /// <returns></returns>
        private void BuildInvSbox()
        {
            this.iSbox = new byte[16, 16] {  // populate the iSbox matrix
    /* 0     1     2     3     4     5     6     7     8     9     a     b     c     d     e     f */
    /*0*/  {0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb},
    /*1*/  {0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb},
    /*2*/  {0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e},
    /*3*/  {0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25},
    /*4*/  {0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92},
    /*5*/  {0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84},
    /*6*/  {0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06},
    /*7*/  {0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b},
    /*8*/  {0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73},
    /*9*/  {0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e},
    /*a*/  {0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b},
    /*b*/  {0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4},
    /*c*/  {0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f},
    /*d*/  {0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef},
    /*e*/  {0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61},
    /*f*/  {0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d} };

        }  // BuildInvSbox()

        /// <summary>
        /// 
        /// </summary>
        /// <returns></returns>
        private void BuildRcon()
        {
            this.Rcon = new byte[11, 4] { {0x00, 0x00, 0x00, 0x00},  
                                   {0x01, 0x00, 0x00, 0x00},
                                   {0x02, 0x00, 0x00, 0x00},
                                   {0x04, 0x00, 0x00, 0x00},
                                   {0x08, 0x00, 0x00, 0x00},
                                   {0x10, 0x00, 0x00, 0x00},
                                   {0x20, 0x00, 0x00, 0x00},
                                   {0x40, 0x00, 0x00, 0x00},
                                   {0x80, 0x00, 0x00, 0x00},
                                   {0x1b, 0x00, 0x00, 0x00},
                                   {0x36, 0x00, 0x00, 0x00} };
        }  // BuildRcon()

        /// <summary>
        /// 
        /// </summary>
        /// <param name="round"></param>
        /// <returns></returns>
        private void AddRoundKey(int round)
        {

            for (int r = 0; r < 4; ++r)
            {
                for (int c = 0; c < 4; ++c)
                {
                    this.State[r, c] = (byte)((int)this.State[r, c] ^ (int)w[(round * 4) + c, r]);
                }
            }
        }  // AddRoundKey()

        /// <summary>
        /// 
        /// </summary>
        /// <returns></returns>
        private void SubBytes()
        {
            for (int r = 0; r < 4; ++r)
            {
                for (int c = 0; c < 4; ++c)
                {
                    this.State[r, c] = this.Sbox[(this.State[r, c] >> 4), (this.State[r, c] & 0x0f)];
                }
            }
        }  // SubBytes

        /// <summary>
        /// 
        /// </summary>
        /// <returns></returns>
        private void InvSubBytes()
        {
            for (int r = 0; r < 4; ++r)
            {
                for (int c = 0; c < 4; ++c)
                {
                    this.State[r, c] = this.iSbox[(this.State[r, c] >> 4), (this.State[r, c] & 0x0f)];
                }
            }
        }  // InvSubBytes

        /// <summary>
        /// 
        /// </summary>
        /// <returns></returns>
        private void ShiftRows()
        {
            byte[,] temp = new byte[4, 4];
            for (int r = 0; r < 4; ++r)  // copy State into temp[]
            {
                for (int c = 0; c < 4; ++c)
                {
                    temp[r, c] = this.State[r, c];
                }
            }

            for (int r = 1; r < 4; ++r)  // shift temp into State
            {
                for (int c = 0; c < 4; ++c)
                {
                    this.State[r, c] = temp[r, (c + r) % Nb];
                }
            }
        }  // ShiftRows()

        /// <summary>
        /// 
        /// </summary>
        /// <returns></returns>
        private void InvShiftRows()
        {
            byte[,] temp = new byte[4, 4];
            for (int r = 0; r < 4; ++r)  // copy State into temp[]
            {
                for (int c = 0; c < 4; ++c)
                {
                    temp[r, c] = this.State[r, c];
                }
            }
            for (int r = 1; r < 4; ++r)  // shift temp into State
            {
                for (int c = 0; c < 4; ++c)
                {
                    this.State[r, (c + r) % Nb] = temp[r, c];
                }
            }
        }  // InvShiftRows()

        /// <summary>
        /// 
        /// </summary>
        /// <returns></returns>
        private void MixColumns()
        {
            byte[,] temp = new byte[4, 4];
            for (int r = 0; r < 4; ++r)  // copy State into temp[]
            {
                for (int c = 0; c < 4; ++c)
                {
                    temp[r, c] = this.State[r, c];
                }
            }

            for (int c = 0; c < 4; ++c)
            {
                this.State[0, c] = (byte)((int)gfmultby02(temp[0, c]) ^ (int)gfmultby03(temp[1, c]) ^
                                           (int)gfmultby01(temp[2, c]) ^ (int)gfmultby01(temp[3, c]));
                this.State[1, c] = (byte)((int)gfmultby01(temp[0, c]) ^ (int)gfmultby02(temp[1, c]) ^
                                           (int)gfmultby03(temp[2, c]) ^ (int)gfmultby01(temp[3, c]));
                this.State[2, c] = (byte)((int)gfmultby01(temp[0, c]) ^ (int)gfmultby01(temp[1, c]) ^
                                           (int)gfmultby02(temp[2, c]) ^ (int)gfmultby03(temp[3, c]));
                this.State[3, c] = (byte)((int)gfmultby03(temp[0, c]) ^ (int)gfmultby01(temp[1, c]) ^
                                           (int)gfmultby01(temp[2, c]) ^ (int)gfmultby02(temp[3, c]));
            }
        }  // MixColumns

        /// <summary>
        /// 
        /// </summary>
        /// <returns></returns>
        private void InvMixColumns()
        {
            byte[,] temp = new byte[4, 4];
            for (int r = 0; r < 4; ++r)  // copy State into temp[]
            {
                for (int c = 0; c < 4; ++c)
                {
                    temp[r, c] = this.State[r, c];
                }
            }

            for (int c = 0; c < 4; ++c)
            {
                this.State[0, c] = (byte)((int)gfmultby0e(temp[0, c]) ^ (int)gfmultby0b(temp[1, c]) ^
                                           (int)gfmultby0d(temp[2, c]) ^ (int)gfmultby09(temp[3, c]));
                this.State[1, c] = (byte)((int)gfmultby09(temp[0, c]) ^ (int)gfmultby0e(temp[1, c]) ^
                                           (int)gfmultby0b(temp[2, c]) ^ (int)gfmultby0d(temp[3, c]));
                this.State[2, c] = (byte)((int)gfmultby0d(temp[0, c]) ^ (int)gfmultby09(temp[1, c]) ^
                                           (int)gfmultby0e(temp[2, c]) ^ (int)gfmultby0b(temp[3, c]));
                this.State[3, c] = (byte)((int)gfmultby0b(temp[0, c]) ^ (int)gfmultby0d(temp[1, c]) ^
                                           (int)gfmultby09(temp[2, c]) ^ (int)gfmultby0e(temp[3, c]));
            }
        }  // InvMixColumns

        private static byte gfmultby01(byte b)
        {
            return b;
        }

        private static byte gfmultby02(byte b)
        {
            if (b < 0x80)
                return (byte)(int)(b << 1);
            else
                return (byte)((int)(b << 1) ^ (int)(0x1b));
        }

        private static byte gfmultby03(byte b)
        {
            return (byte)((int)gfmultby02(b) ^ (int)b);
        }

        private static byte gfmultby09(byte b)
        {
            return (byte)((int)gfmultby02(gfmultby02(gfmultby02(b))) ^
                           (int)b);
        }

        private static byte gfmultby0b(byte b)
        {
            return (byte)((int)gfmultby02(gfmultby02(gfmultby02(b))) ^
                           (int)gfmultby02(b) ^
                           (int)b);
        }

        private static byte gfmultby0d(byte b)
        {
            return (byte)((int)gfmultby02(gfmultby02(gfmultby02(b))) ^
                           (int)gfmultby02(gfmultby02(b)) ^
                           (int)(b));
        }

        private static byte gfmultby0e(byte b)
        {
            return (byte)((int)gfmultby02(gfmultby02(gfmultby02(b))) ^
                           (int)gfmultby02(gfmultby02(b)) ^
                           (int)gfmultby02(b));
        }

        private void KeyExpansion()
        {
            this.w = new byte[Nb * (Nr + 1), 8];  // 4 columns of bytes corresponds to a word

            for (int row = 0; row < Nk; ++row)
            {
                this.w[row, 0] = this.key[4 * row];
                this.w[row, 1] = this.key[4 * row + 1];
                this.w[row, 2] = this.key[4 * row + 2];
                this.w[row, 3] = this.key[4 * row + 3];
            
            }

            byte[] temp = new byte[8];

            for (int row = Nk; row < Nb * (Nr + 1); ++row)
            {
                temp[0] = this.w[row - 1, 0]; temp[1] = this.w[row - 1, 1];
                temp[2] = this.w[row - 1, 2]; temp[3] = this.w[row - 1, 3];
             


                if (row % Nk == 0)
                {
                    temp = SubWord(RotWord(temp));

                    temp[0] = (byte)((int)temp[0] ^ (int)this.Rcon[row / Nk, 0]);
                    temp[1] = (byte)((int)temp[1] ^ (int)this.Rcon[row / Nk, 1]);
                    temp[2] = (byte)((int)temp[2] ^ (int)this.Rcon[row / Nk, 2]);
                    temp[3] = (byte)((int)temp[3] ^ (int)this.Rcon[row / Nk, 3]);
                }
                else if (Nk > 6 && (row % Nk == 4))
                {
                    temp = SubWord(temp);
                }

                // w[row] = w[row-Nk] xor temp
                this.w[row, 0] = (byte)((int)this.w[row - Nk, 0] ^ (int)temp[0]);
                this.w[row, 1] = (byte)((int)this.w[row - Nk, 1] ^ (int)temp[1]);
                this.w[row, 2] = (byte)((int)this.w[row - Nk, 2] ^ (int)temp[2]);
                this.w[row, 3] = (byte)((int)this.w[row - Nk, 3] ^ (int)temp[3]);

            }  // for loop
        }  // KeyExpansion()

        private byte[] SubWord(byte[] word)
        {
            byte[] result = new byte[8];
            result[0] = this.Sbox[word[0] >> 4, word[0] & 0x0f];
            result[1] = this.Sbox[word[1] >> 4, word[1] & 0x0f];
            result[2] = this.Sbox[word[2] >> 4, word[2] & 0x0f];
            result[3] = this.Sbox[word[3] >> 4, word[3] & 0x0f];
        
            return result;
        }

        private byte[] RotWord(byte[] word)
        {
            byte[] result = new byte[8];
            result[0] = word[1];
            result[1] = word[2];
            result[2] = word[3];
            result[3] = word[0];
            
            return result;
        }
    }
}


        }

Posted 25-May-12 10:24am

Member 8805462

Updated 30-May-12 15:44pm

El_Codero

v4

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El_Codero 25-May-12 16:26pm

Code Tags added.

Member 8805462 25-May-12 16:41pm

why i cant see ur comment?

El_Codero 25-May-12 18:00pm

I just added "Code Tags added." ;). Thinking about your problem, but don't understand it yet. What means "But when i give different password to decrypt the .jpeg file (or anyone) again the system is encrypted it". When encrypting a file, you need same password to decrypt it.

Member 8805462 26-May-12 5:56am

Yes i know i need same password but i can't do that.it should be same password encrypt and decrypt a file but if i use different password to decryption and encryption again the prokram is working how can i arrange it SAME password do both encryption and decryption??

3 solutions

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This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

John Orendt · Answer 1 · 2012-05-25T21:29:00

Solution 1

Your question is not very clear.

Anyway this should help

Simple encrypting and decrypting data in C#

First create a sample text file called "Clear.txt"

then call method TestFileCrypto()

C#

public void TestFileCrypto()
{
 String password = "MyPassword";
 Encrypt("Clear.txt", "Cipher.txt", password);
 Decrypt("Cipher.txt", "RoundTrip.txt", password);
}

Thereafter, examine file "Cipher.txt", it should be incomprehensible.

Next, compare files "Clear.txt" and "RoundTrip.txt", they should be identical.

Try this and tell us what happens in detail.

Posted 25-May-12 21:29pm

John Orendt

Updated 26-May-12 0:34am

v2

Comments

Member 8805462 26-May-12 5:50am

I dont want to use ready library for AES256 encryprion
i want to add these codes symmetric key algorithm.
how can i use same password encryption and decryption?
after i took a password to encrypt a file I HAVE TO DECRYPT IT WITH SAME' PASSWORD NOT ANY OTHER PASSWORD

Member 8805462 26-May-12 8:58am

its not reading the method
actually i should encrypt any file out of .txt

John Orendt 26-May-12 14:30pm

Please clarify, when running TestFileCrypto() did an error occur? if so on what line?

El_Codero · Answer 2 · 2012-05-30T15:41:00

Do you have tried John's solution?
Is upper code your code? Don't want to bother you, but I think this isn't yours, otherwise you would excatly know where to look at.

Still don't really understand what works...or does not.

For the case you are working with above class means you encrypt a file with no errors but decrypting it with also same password you got an exception?

Then something must be wrong with decryption code/difference in how bytes/rows/... readed.

Why not using AES-Class?

msdn.microsoft.com/en-US/library/system.security.cryptography.aes.aspx

Regards

MugiwaraUK · Answer 3 · 2012-05-30T22:44:00

You do not set the key bytes anywhere in this method, so the password bytes are the same no matter what password you use

C#

public Aes(KeySize keySize, byte[] keyBytes, BlockSize blockSize)
       {

           BuildNaNkNr();

           SetNbNkNr(keySize, blockSize);

           this.key = new byte[this.Nk * 4];  // 16, 24, 32 bytes
           //keyBytes.CopyTo(this.key, 0);

           BuildSbox();
           BuildInvSbox();
           BuildRcon();
           KeyExpansion();  // expand the seed key into a key schedule and store in w

       }  // Aes constructor

AES 256 file encryption key mistake

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