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Decrypted zip file is invalid can't open it

My problem is that the created encrypted zip file is unable to open after decrypting it. It says the compressed file is invalid. File it self almost doubled it's initial space after decrypting from 15 KB to 27 KB. The problem occours on zip files, when I encrypted and decryped a xml file it worked just fine. Below my whole code.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;
using System.IO;
namespace EDI
{
public class EncryptionHelper
{
public void Main()
{
var file = #"C:\Temp\test.zip";
AesCryptoServiceProvider AES = new AesCryptoServiceProvider();
AES.Padding = PaddingMode.PKCS7;
AES.Mode = CipherMode.CBC;
AES.BlockSize = 128;
AES.KeySize = 128;
AES.GenerateKey();
AES.GenerateIV();
var key = AES.Key;
var iv = AES.IV;
encryptAES(AES, file, key, iv);
decryptAES(AES, file + ".encrypted", key, iv);
}
public void encryptAES(SymmetricAlgorithm algo, string filePath, byte[] key, byte[] IV)
{
using (FileStream fin = new FileStream(filePath, FileMode.Open, FileAccess.Read))
{
using (FileStream fout = new FileStream(filePath + ".encrypted", FileMode.OpenOrCreate, FileAccess.Write))
{
using (ICryptoTransform crypt = algo.CreateEncryptor(key, IV))
{
using (CryptoStream crStream = new CryptoStream(fout, crypt, CryptoStreamMode.Write))
{
fin.CopyTo(crStream);
}
}
}
}
}
public void decryptAES(SymmetricAlgorithm algo, string filePath, byte[] key, byte[] IV)
{
using (FileStream fStream = new FileStream(filePath, FileMode.Open, FileAccess.Read))
{
using (ICryptoTransform crypt = algo.CreateDecryptor(key, IV))
{
using (CryptoStream crStream = new CryptoStream(fStream, crypt, CryptoStreamMode.Read))
{
using (StreamReader reader = new StreamReader(crStream))
{
string data = reader.ReadToEnd();
File.WriteAllText(filePath.Replace(".encrypted", ".restored"), data);
}
}
}
}
}
}
}
Edit to show the fix.
using (FileStream writer = new FileStream(filePath + ".decrypted", FileMode.Create, FileAccess.Write))
// using (Read reader = new StreamReader(crStream))
{
// string data = reader.ReadToEnd();
// File.WriteAllText(filePath.Replace(".encrypted", ".restored"), data);
crStream.CopyTo(writer);
}

Encryption of file using algorithm Salsa20

I'm doing my homework. It's connected with encryption of file.
I use algorithm Salsa20
Here's my code:
using (var salsa = new Salsa20.Salsa20())
{
using (var fstream_out = new FileStream(filePath, FileMode.Truncate, FileAccess.ReadWrite, FileShare.Write))
{
salsa.Key = key;
salsa.IV = iv;
using (var cstream = new CryptoStream(fstream_out, salsa.CreateEncryptor(), CryptoStreamMode.Write))
{
var bytes = File.ReadAllBytes(filePath);
cstream.Write(bytes, 0, 1000000);
}
}
}
When I try to encrypt file, there's exception "The process cannot access the file because it is being used by another process."
What's wrong?

Add cleartext bytes to the beginning of a CryptoStream?

I have an interface defined like so:
public interface IEncryptionService
{
Stream Encrypt(Stream cleartext);
Stream Decrypt(Stream encrypted);
}
I am implementing this interface with an AesCryptoServiceProvider, but there's clearly a problem here. The IV (Initialization Vector) is not returned on the interface... so encrypting something would work fine, as long as I have no desire to decrypt it ever again. The Decrypt() method has no chance at all of working.
What I want to do is include the IV in cleartext at the beginning of the stream, then add the CryptoStream to it, so it is essentially encrypted data with a "header" that I could strip off and use for decrypting the stream.
So... how would I do that? I can create the CryptoStream easy enough, but it looks like this would encrypt the IV, which kinda defeats the purpose. I could load the CryptoStream into memory, prepend the IV, and then stream it out as a MemoryStream, but this would be really inefficient, and would die on large streams.
What is a good, secure, scalable practice for this?

Here is what I had in mind. See how you write the IV to the MemoryStream and then follow it with the crypto? Then when you want to decrypt, pull the IV off first in the same way.
Sorry, been a long time. This one is working. It should scale well if you don't cast ms toArray(); at the end. For example write to FileStream as you go and you should not need much memory at all. This is just to demo prepending the IV.
private byte[] encrypt(byte[] originalPlaintextBytes)
{
using (SymmetricAlgorithm algorithm = AesCryptoServiceProvider.Create())
{
algorithm.GenerateKey();
algorithm.GenerateIV();
byte[] iv = algorithm.IV;
byte[] key = algorithm.Key;
using (ICryptoTransform encryptor = algorithm.CreateEncryptor(key, iv))
{
using (MemoryStream ms = new MemoryStream())
using (CryptoStream cs = new CryptoStream(ms, encryptor,CryptoStreamMode.Write))
{
BinaryWriter bw = new BinaryWriter(ms);
bw.Write(iv);
cs.Write(originalPlaintextBytes, 0, originalPlaintextBytes.Length);
return ms.ToArray();
}
}
}
}
OK rather than edit the above code, here is a whole program that randomly creates a plaintext file of 1 megabyte. Then it encrypts it into ciphertext. Note that this program does not ever need 1 megabyte of memory in which to operate. It is completely scalable. Again, as before, this program is to demonstrate the concept, and you would do better with a readBuffer larger than 1 byte. But I did not want to create that and obscure the core answer. I hope this helps. I think it is exactly the kind of approach you need.
using System;
using System.IO;
using System.Security.Cryptography;
using System.Windows.Forms;
namespace SO_AES
{
public partial class Form1 : Form
{
Random ran = new Random();
public Form1()
{
InitializeComponent();
using (var file = File.Open("Plaintext.txt", FileMode.OpenOrCreate))
{
byte[] junkBytes = new byte[1000];
for (int i = 0; i < 1000; i++)
{
for (int j = 0; j < 1000; j++)
{
junkBytes[j] = (byte)ran.Next(0, 255);
}
file.Write(junkBytes, 0, junkBytes.Length);
}
}
using (var plainTextFile = File.Open("Plaintext.txt", FileMode.Open))
{
using (var cryptoTextFile = File.Open("Crypto.txt", FileMode.OpenOrCreate))
{
encrypt(plainTextFile, cryptoTextFile);
}
}
}
void encrypt(Stream inStream, Stream outStream)
{
using (SymmetricAlgorithm algorithm = AesCryptoServiceProvider.Create())
{
algorithm.GenerateKey();
algorithm.GenerateIV();
byte[] iv = algorithm.IV;
byte[] key = algorithm.Key;
using (ICryptoTransform encryptor = algorithm.CreateEncryptor(key, iv))
{
using (CryptoStream cs = new CryptoStream(outStream, encryptor, CryptoStreamMode.Write))
{
BinaryWriter bw = new BinaryWriter(outStream);
bw.Write(iv);
byte[] readBuffer = new byte[1];
BinaryReader br = new BinaryReader(inStream);
while (br.Read(readBuffer, 0, readBuffer.Length) != 0)
{
cs.Write(readBuffer, 0, 1);
}
}
}
}
inStream.Close();
outStream.Close();
}
}
}

C# encryption and decryption

In c#.net, when im trying to decrypt the file it shows me this error but it works for encryption.
ERROR: The process cannot access the file SecureDownloadManager.log because it is being used by another process
Code:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Security;
using System.Security.Cryptography;
using System.IO;
using System.Text.RegularExpressions;
using System.Runtime.InteropServices;
namespace Encryption
{
public partial class Form1 : Form
{
string inputFile;
string outputFile;
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
//EncryptFile();
try
{
OpenFileDialog dialog = new OpenFileDialog();
dialog.Filter = "All Files (*.*)|";
dialog.InitialDirectory = #"Desktop";
dialog.Title = "Please select a file to encrypt.";
dialog.ShowDialog();
inputFile = dialog.FileName;
outputFile = inputFile;
string password = #"myKey123"; // Your Key Here
UnicodeEncoding UE = new UnicodeEncoding();
byte[] key = UE.GetBytes(password);
string cryptFile = outputFile;
FileStream fsCrypt = new FileStream(cryptFile, FileMode.Create);
RijndaelManaged RMCrypto = new RijndaelManaged();
CryptoStream cs = new CryptoStream(fsCrypt,
RMCrypto.CreateEncryptor(key, key),
CryptoStreamMode.Write);
FileStream fsIn = new FileStream(inputFile, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
int data;
while ((data = fsIn.ReadByte()) != -1)
cs.WriteByte((byte)data);
fsIn.Close();
cs.Close();
fsCrypt.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
private void button2_Click(object sender, EventArgs e)
{ //Decrypt File
try
{
OpenFileDialog dialog = new OpenFileDialog();
dialog.Filter = "All Files (*.*)|";
dialog.InitialDirectory = #"Desktop";
dialog.Title = "Please select a file to decrypt.";
dialog.ShowDialog();
inputFile = dialog.FileName;
outputFile = inputFile;
string password = #"myKey123"; // Your Key Here
UnicodeEncoding UE = new UnicodeEncoding();
byte[] key = UE.GetBytes(password);
string cryptFile = outputFile;
FileStream fsCrypt = new FileStream(inputFile, FileMode.Create);
RijndaelManaged RMCrypto = new RijndaelManaged();
CryptoStream cs = new CryptoStream(fsCrypt,
RMCrypto.CreateDecryptor(key, key),
CryptoStreamMode.Read);
FileStream fsOut = new FileStream(outputFile, FileMode.Open, FileAccess.Write, FileShare.ReadWrite);
int data;
while ((data = cs.ReadByte()) != -1)
fsOut.WriteByte((byte)data);
fsOut.Close();
cs.Close();
fsCrypt.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
}
}

Try the following code and let me know if it resolves the problem.
//EncryptFile();
try
{
OpenFileDialog dialog = new OpenFileDialog();
dialog.Filter = "All Files (*.*)|";
dialog.InitialDirectory = #"Desktop";
dialog.Title = "Please select a file to encrypt.";
dialog.ShowDialog();
inputFile = dialog.FileName;
outputFile = inputFile;
string password = #"myKey123"; // Your Key Here
UnicodeEncoding UE = new UnicodeEncoding();
byte[] key = UE.GetBytes(password);
string cryptFile = outputFile;
using (FileStream fsCrypt = new FileStream(cryptFile, FileMode.Create))
{
RijndaelManaged RMCrypto = new RijndaelManaged();
using (CryptoStream cs = new CryptoStream(fsCrypt,
RMCrypto.CreateEncryptor(key, key),
CryptoStreamMode.Write))
{
using (FileStream fsIn = new FileStream(inputFile, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
{
int data;
while ((data = fsIn.ReadByte()) != -1)
cs.WriteByte((byte)data);
}
}
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}

The error is due to the objects not being completely disposed. You need to use a 'using' clause to release objects after use.
You can use the following code that uses FileStream instead:
System.IO.File.WriteAllBytes(outputFile);
which replaces:
FileStream fsOut = new FileStream(outputFile, FileMode.Open, FileAccess.Write, FileShare.ReadWrite);
int data;
while ((data = cs.ReadByte()) != -1)
fsOut.WriteByte((byte)data);
fsOut.Close();
cs.Close();
fsCrypt.Close();
I hope it resolves your issue.

C# DES File Decryption Breaking Non-Text Files

I have these two methods which are pretty much copy+pastes from http://support.microsoft.com/kb/307010.
When I decrypt the files, if they are any type of text file such as .txt, .xml, .html, etc. I can open them up and everything is fine. Any type of file not just text, such as .exe, .jpg, .pdf, etc. all break when decrypted. Is there anything I am doing wrong? Are these methods using binary to encrypt/decrypt the files? If not is there a way I can make it binary?
Any help is greatly appreciated!
public static void EncryptFile(string sInputFilename,
string sOutputFilename,
string sKey)
{
FileStream fsInput = new FileStream(sInputFilename,
FileMode.Open,
FileAccess.Read);
FileStream fsEncrypted = new FileStream(sOutputFilename,
FileMode.Create,
FileAccess.Write);
DESCryptoServiceProvider DES = new DESCryptoServiceProvider();
DES.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
DES.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
ICryptoTransform desencrypt = DES.CreateEncryptor();
CryptoStream cryptostream = new CryptoStream(fsEncrypted,
desencrypt,
CryptoStreamMode.Write);
byte[] bytearrayinput = new byte[fsInput.Length];
fsInput.Read(bytearrayinput, 0, bytearrayinput.Length);
cryptostream.Write(bytearrayinput, 0, bytearrayinput.Length);
cryptostream.Close();
fsInput.Close();
fsEncrypted.Close();
}
public 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());
fsDecrypted.Flush();
fsDecrypted.Close();
fsread.Close();
cryptostreamDecr.Close();
}

I don't know what the guy that wrote that article was smoking, but:
DESCryptoServiceProvider desCrypto =
(DESCryptoServiceProvider)DESCryptoServiceProvider.Create();
return ASCIIEncoding.ASCII.GetString(desCrypto.Key);
will not get you a valid key. At least one problem is the fact that the key you use to encrypt is not the same key that you're using to decrypt, because you can't convert bytes to ASCII and back like that.
If you want to treat the key as a string, what you probably want is:
string keyAsString = Convert.ToBase64String(desCrypto.Key);
Then when you want to turn it back into bytes, instead of ASCIIEncoding.ASCII.GetBytes, you'll do:
byte[] key = Convert.FromBase64String(keyAsString);
EDIT
There's a ton more wrong with that article too. I'd say ignore that one and find a better example.
EDIT
Here's a very clean basic AES working example that I use for my standard encryption needs. Some of the major improvements over the article are:
Proper creation of a key
Current algorithm (AES 256-bit key)
Random IV
Buffered file access instead of reading/writing the entire file in one chunk
Wrapping all the disposable objects in using
Aside from that, it's the same basic idea.
using System;
using System.IO;
using System.Security.Cryptography;
namespace ConsoleApplication12
{
class Program
{
private const int KEY_SIZE_BYTES = 32;
private const int IV_SIZE_BYTES = 16;
static void Main(string[] args)
{
var rand = new Random();
using (var fs = File.Open(#"C:\temp\input.bin", FileMode.Create, FileAccess.Write, FileShare.None))
{
byte[] buffer = new byte[10000];
for (int i = 0; i < 100; ++i)
{
rand.NextBytes(buffer);
fs.Write(buffer, 0, buffer.Length);
}
}
string key = GenerateRandomKey();
Encrypt(#"C:\temp\input.bin", #"C:\temp\encrypted.bin", key);
Decrypt(#"C:\temp\encrypted.bin", #"C:\temp\decyrypted.bin", key);
}
static string GenerateRandomKey()
{
byte[] key = new byte[KEY_SIZE_BYTES];
using (var rng = RandomNumberGenerator.Create())
{
rng.GetBytes(key);
}
return Convert.ToBase64String(key);
}
static void Encrypt(string inputFile, string outputFile, string key)
{
const int BUFFER_SIZE = 8192;
byte[] buffer = new byte[BUFFER_SIZE];
byte[] keyBytes = Convert.FromBase64String(key);
byte[] ivBytes = new byte[IV_SIZE_BYTES];
using (var rng = RandomNumberGenerator.Create())
{
rng.GetBytes(ivBytes);
}
using (var inputStream = File.Open(inputFile, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
{
using (var outputStream = File.Open(outputFile, FileMode.Create, FileAccess.Write, FileShare.None))
{
outputStream.Write(ivBytes, 0, ivBytes.Length);
using (var cryptoAlgo = Aes.Create())
{
using (var encryptor = cryptoAlgo.CreateEncryptor(keyBytes, ivBytes))
{
using (var cryptoStream = new CryptoStream(outputStream, encryptor, CryptoStreamMode.Write))
{
int count;
while ((count = inputStream.Read(buffer, 0, buffer.Length)) > 0)
{
cryptoStream.Write(buffer, 0, count);
}
}
}
}
}
}
}
static void Decrypt(string inputFile, string outputFile, string key)
{
const int BUFFER_SIZE = 8192;
byte[] buffer = new byte[BUFFER_SIZE];
byte[] keyBytes = Convert.FromBase64String(key);
byte[] ivBytes = new byte[IV_SIZE_BYTES];
using (var inputStream = File.Open(inputFile, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
{
inputStream.Read(ivBytes, 0, ivBytes.Length);
using (var outputStream = File.Open(outputFile, FileMode.Create, FileAccess.Write, FileShare.None))
{
using (var cryptoAlgo = Aes.Create())
{
using (var decryptor = cryptoAlgo.CreateDecryptor(keyBytes, ivBytes))
{
using (var cryptoStream = new CryptoStream(inputStream, decryptor, CryptoStreamMode.Read))
{
int count;
while ((count = cryptoStream.Read(buffer, 0, buffer.Length)) > 0)
{
outputStream.Write(buffer, 0, count);
}
}
}
}
}
}
}
}
}
Because the IV is random, you'll see another small difference in technique. When encrypting the file, you first write the IV to the encrypted file (it's not a secret, so you just write it straight out). When decrypting the file, you read the first few bytes to retrieve the IV, then the rest of the file contains the actual encrypted data. The purpose of a random IV is so the same plaintext file will encrypt into a different encrypted file every time you run it.
The Main method here demonstrates encryption with a random key. If you want to use a password, it's a little more work, but you can implement PBKDF2 with maybe a dozen or so extra lines of code.