I have to perform the encryption and decryption of the file based on des algorithm.
The encryption performed well but the decryption having the error as Bad Data when perform the readtoend function.
The coding is given below:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Drawing;
using System.Text;
using System.Runtime.InteropServices;
using System.Security.Cryptography;
using System.IO;
public partial class _Default : System.Web.UI.Page
{
string sSecretKey;
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Button1_Click(object sender, EventArgs e)
{
sSecretKey = GenerateKey();
DecryptFile(@"E:\Encryptedd.txt", @"E:\Decrypteddd.txt", sSecretKey);
// For additional security Pin the key.
GCHandle gch = GCHandle.Alloc(sSecretKey, GCHandleType.Pinned);
// Remove the Key from memory.
ZeroMemory(gch.AddrOfPinnedObject(), sSecretKey.Length * 2);
gch.Free();
}
static void DecryptFile(string sInputFilename,string sOutputFilename,string sKey)
{
DESCryptoServiceProvider DES = new DESCryptoServiceProvider();
//A 64 bit key and IV is required for this provider.
//Set secret key For DES algorithm.
DES.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
//Set initialization vector.
DES.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
//Create a file stream to read the encrypted file back.
FileStream fsread = new FileStream(sInputFilename,FileMode.Open,FileAccess.Read);
//Create a DES decryptor from the DES instance.
ICryptoTransform desdecrypt = DES.CreateDecryptor();
//Create crypto stream set to read and do a
//DES decryption transform on incoming bytes.
CryptoStream cryptostreamDecr = new CryptoStream(fsread,desdecrypt,CryptoStreamMode.Read);
//Print the contents of the decrypted file.
StreamWriter fsDecrypted = new StreamWriter(sOutputFilename);
fsDecrypted.Write(new StreamReader(cryptostreamDecr).ReadToEnd());
> //the error bad data
fsDecrypted.Flush();
fsDecrypted.Close();
}
[System.Runtime.InteropServices.DllImport("KERNEL32.DLL",EntryPoint = "RtlZeroMemory")]
public static extern bool ZeroMemory(IntPtr Destination, int Length);
// Function to Generate a 64 bits Key.
static string GenerateKey()
{
// Create an instance of Symetric Algorithm. Key and IV is generated automatically.
DESCryptoServiceProvider desCrypto = (DESCryptoServiceProvider)
DESCryptoServiceProvider.Create();
// Use the Automatically generated key for Encryption.
return ASCIIEncoding.ASCII.GetString(desCrypto.Key);
}
}
Please help me.
