I've code to decrypt file in DES Encryption, I try I keep getting the file even though I enter the key at the time when the key decrypt the encrypted differently. But i've get the error.
while ((data = cryptostreamDecr.ReadByte()) != -1) // Message Error : Bad Data.
Which code should I add or change in order to keep the process running decrypt?
private static void DecryptFile(string sInputFilename, string sKey)
{
var DES = new DESCryptoServiceProvider();
DES.Key = Encoding.ASCII.GetBytes(sKey);
DES.IV = Encoding.ASCII.GetBytes(sKey);
ICryptoTransform desdecrypt = DES.CreateDecryptor();
using (var fsread = new FileStream(sInputFilename, FileMode.Open,
FileAccess.ReadWrite))
{
using (var cryptostreamDecr = new CryptoStream(fsread,
desdecrypt,
CryptoStreamMode.Read))
{
int data;
fsread.Flush();
using (var ms = new MemoryStream())
{
while ((data = cryptostreamDecr.ReadByte()) != -1)
{
ms.WriteByte((byte)data);
}
cryptostreamDecr.Close();
using (var fsWrite = new FileStream(sInputFilename, FileMode.Truncate))
{
ms.WriteTo(fsWrite);
ms.Flush();
}
}
}
}
}
Encrypt Code :
public static void EncryptFile(string sInputFilename, string sKey)
{
FileStream fsInput = new FileStream(sInputFilename,
FileMode.Open,
FileAccess.ReadWrite);
DESCryptoServiceProvider DES = new DESCryptoServiceProvider();
DES.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
DES.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
ICryptoTransform desencrypt = DES.CreateEncryptor();
CryptoStream cryptostream = new CryptoStream(fsInput,
desencrypt,
CryptoStreamMode.Write);
byte[] bytearrayinput = new byte[fsInput.Length];
fsInput.Read(bytearrayinput, 0, bytearrayinput.Length);
fsInput.SetLength(0);
cryptostream.Write(bytearrayinput, 0, bytearrayinput.Length);
cryptostream.FlushFinalBlock();
cryptostream.Close();
fsInput.Close();
}
[EDIT] : remove in Encypt :
cryptostream.FlushFinalBlock();
And add in decrypt
DES.Padding = PaddingMode.None;
64 bits is the only valid key size for the DES encryption algorithm.
8 bits is equal to one ASCII character means 64 bits is equal to 8 Characters.
If you send 8 characters only then check this (C# "Bad Data" exception when decrypting encrypted file). It may solve your problem.
[Edit]
Add DES.Padding = PaddingMode.None; in DecryptFile.
Related
Many years ago I used this code to encrypt an entire file:
public static void CryptFile(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();
}
Today I tried to use it again but I always get this error:
the specified key size is not valid for this algorithm.
I have tried with many strings of varying length but cannot understand which is the correct length to use.
The correct length is 8 characters, such as "12345678"
I'm trying to encrypt and decrypt a file using AES. The problem that I have is that when the file gets decrypted, it is broken and you can't open it. The original file has a length of 81.970 bytes and the decrypted file has a length of 81.984 bytes...so there are 14 bytes added for some reason. The problem could be in the way the file gets encrypted but I don't know what I'm doing wrong.
What am I missing here? Could it be the way I'm processing the password, the iv and the padding?
Thanks for your time!
This is the code I use to encrypt:
private AesManaged aesManaged;
private string filePathToEncrypt;
public Encrypt(AesManaged aesManaged, string filePathToEncrypt)
{
this.aesManaged = aesManaged;
this.filePathToEncrypt = filePathToEncrypt;
}
public void DoEncryption()
{
byte[] cipherTextBytes;
byte[] textBytes = File.ReadAllBytes(this.filePathToEncrypt);
using(ICryptoTransform encryptor = aesManaged.CreateEncryptor(aesManaged.Key, aesManaged.IV))
using (MemoryStream ms = new MemoryStream())
using (CryptoStream cs = new CryptoStream(ms, encryptor, CryptoStreamMode.Write))
{
cs.Write(textBytes, 0, textBytes.Length);
cs.FlushFinalBlock();
cipherTextBytes = ms.ToArray();
}
File.WriteAllBytes("EncryptedFile.aes", cipherTextBytes);
}
This is the code I use to decrypt:
private AesManaged aesManaged;
private string filePathToDecrypt;
public Decrypt(AesManaged aesManaged, string filePathToDecrypt)
{
this.aesManaged = aesManaged;
this.filePathToDecrypt = filePathToDecrypt;
}
public void DoDecrypt()
{
byte[] cypherBytes = File.ReadAllBytes(this.filePathToDecrypt);
byte[] clearBytes = new byte[cypherBytes.Length];
ICryptoTransform encryptor = aesManaged.CreateDecryptor(aesManaged.Key, aesManaged.IV);
using (MemoryStream ms = new MemoryStream(cypherBytes))
using (CryptoStream cs = new CryptoStream(ms, encryptor, CryptoStreamMode.Read))
{
cs.Read(clearBytes, 0, clearBytes.Length);
clearBytes = ms.ToArray();
}
File.WriteAllBytes("DecryptedFile.gif", clearBytes);
}
And here is how I call the functions:
string filePathToEncrypt = "dilbert.gif";
string filePathToDecrypt = "EncryptedFile.aes";
string password = "Password";
string passwordSalt = "PasswordSalt";
Rfc2898DeriveBytes deriveBytes = new Rfc2898DeriveBytes(password, Encoding.ASCII.GetBytes(passwordSalt));
var aesManaged = new AesManaged
{
Key = deriveBytes.GetBytes(128 / 8),
IV = deriveBytes.GetBytes(16),
Padding = PaddingMode.PKCS7
};
Console.WriteLine("Encrypting File...");
var encryptor = new Encrypt(aesManaged, filePathToEncrypt);
encryptor.DoEncryption();
Thread.Sleep(300);
Console.WriteLine("Decrypting File...");
var decryptor = new Decrypt(aesManaged, filePathToDecrypt);
decryptor.DoDecrypt();
Thread.Sleep(300);
Try with:
public void DoEncryption()
{
byte[] cipherBytes;
byte[] textBytes = File.ReadAllBytes(this.filePathToEncrypt);
using (ICryptoTransform encryptor = aesManaged.CreateEncryptor(aesManaged.Key, aesManaged.IV))
using (MemoryStream input = new MemoryStream(textBytes))
using (MemoryStream output = new MemoryStream())
using (CryptoStream cs = new CryptoStream(output, encryptor, CryptoStreamMode.Write))
{
input.CopyTo(cs);
cs.FlushFinalBlock();
cipherBytes = output.ToArray();
}
File.WriteAllBytes("EncryptedFile.aes", cipherBytes);
}
and
public void DoDecrypt()
{
byte[] cypherBytes = File.ReadAllBytes(this.filePathToDecrypt);
byte[] textBytes;
using (ICryptoTransform decryptor = aesManaged.CreateDecryptor(aesManaged.Key, aesManaged.IV))
using (MemoryStream input = new MemoryStream(cypherBytes))
using (MemoryStream output = new MemoryStream())
using (CryptoStream cs = new CryptoStream(input, decryptor, CryptoStreamMode.Read))
{
cs.CopyTo(output);
textBytes = output.ToArray();
}
File.WriteAllBytes("DecryptedFile.gif", textBytes);
}
Note that the code could be modified to not use temporary byte[] and read/write directly to input/output streams.
In general you can't desume the length of the plaintext from the length of the cyphertext, so this line:
new byte[cypherBytes.Length]
was totally wrong.
And please, don't use Encoding.ASCII in 2016. It is so like previous century. Use Encoding.UTF8 to support non-english characters.
The answer may be very simple. I don't see where do u try to choose a cipher mode, so by default it probably takes CBC, as IV was inited. Then, 81.970 are padded by 14 bytes, to be divisible by 32. So when it happens, the memory you allocated was just 81.970, so the padding bytes doesn't write correctly, cause of some sort of memory leak, and when decrypt is started, unpadding doesn't work correctly.
I have error from CryptoStream:
Padding is invalid and cannot be removed.
Code
public MemoryStream EncrypteBytes(Stream inputStream, string passPhrase, string saltValue)
{
RijndaelManaged RijndaelCipher = new RijndaelManaged();
RijndaelCipher.Padding = PaddingMode.PKCS7;
RijndaelCipher.Mode = CipherMode.CBC;
byte[] salt = Encoding.ASCII.GetBytes(saltValue);
PasswordDeriveBytes password = new PasswordDeriveBytes(passPhrase, salt, "SHA1", 2);
ICryptoTransform Encryptor = RijndaelCipher.CreateEncryptor(password.GetBytes(32), password.GetBytes(16));
MemoryStream memoryStream = new MemoryStream();
CryptoStream cryptoStream = new CryptoStream(memoryStream, Encryptor, CryptoStreamMode.Write);
var buffer = new byte[1024];
var read = inputStream.Read(buffer, 0, buffer.Length);
while (read > 0)
{
cryptoStream.Write(buffer, 0, read);
read = inputStream.Read(buffer, 0, buffer.Length);
}
cryptoStream.FlushFinalBlock();
memoryStream.Position = 0;
return memoryStream;
}
// Example usage: DecryptBytes(encryptedBytes, "SensitivePhrase", "SodiumChloride");
public byte[] DecrypteBytes(MemoryStream memoryStream, string passPhrase, string saltValue)
{
RijndaelManaged RijndaelCipher = new RijndaelManaged();
RijndaelCipher.Padding = PaddingMode.PKCS7;
RijndaelCipher.Mode = CipherMode.CBC;
byte[] salt = Encoding.ASCII.GetBytes(saltValue);
PasswordDeriveBytes password = new PasswordDeriveBytes(passPhrase, salt, "SHA1", 2);
ICryptoTransform Decryptor = RijndaelCipher.CreateDecryptor(password.GetBytes(32), password.GetBytes(16));
CryptoStream cryptoStream = new CryptoStream(memoryStream, Decryptor, CryptoStreamMode.Read);
byte[] plainBytes = new byte[memoryStream.Length];
int DecryptedCount = cryptoStream.Read(plainBytes, 0, plainBytes.Length);
return plainBytes;
}
Use PaddingMode.Zeros to fix problem , Following code:
public byte[] EncryptFile(Stream input, string password, string salt)
{
// Essentially, if you want to use RijndaelManaged as AES you need to make sure that:
// 1.The block size is set to 128 bits
// 2.You are not using CFB mode, or if you are the feedback size is also 128 bits
var algorithm = new RijndaelManaged { KeySize = 256, BlockSize = 128 };
var key = new Rfc2898DeriveBytes(password, Encoding.ASCII.GetBytes(salt));
algorithm.Key = key.GetBytes(algorithm.KeySize / 8);
algorithm.IV = key.GetBytes(algorithm.BlockSize / 8);
algorithm.Padding = PaddingMode.Zeros;
using (Stream cryptoStream = new MemoryStream())
using (var encryptedStream = new CryptoStream(cryptoStream, algorithm.CreateEncryptor(), CryptoStreamMode.Write))
{
CopyStream(input, encryptedStream);
return ReadToEnd(cryptoStream);
}
}
public byte[] DecryptFile(Stream input, Stream output, string password, string salt)
{
// Essentially, if you want to use RijndaelManaged as AES you need to make sure that:
// 1.The block size is set to 128 bits
// 2.You are not using CFB mode, or if you are the feedback size is also 128 bits
var algorithm = new RijndaelManaged { KeySize = 256, BlockSize = 128 };
var key = new Rfc2898DeriveBytes(password, Encoding.ASCII.GetBytes(salt));
algorithm.Key = key.GetBytes(algorithm.KeySize / 8);
algorithm.IV = key.GetBytes(algorithm.BlockSize / 8);
algorithm.Padding = PaddingMode.Zeros;
try
{
using (var decryptedStream = new CryptoStream(output, algorithm.CreateDecryptor(), CryptoStreamMode.Write))
{
CopyStream(input, decryptedStream);
return ReadToEnd(output);
}
}
catch (CryptographicException ex)
{
throw new InvalidDataException("Please supply a correct password");
}
catch (Exception ex)
{
throw new Exception(ex.Message);
}
}
I hop help you.
Please check your pass phrase - it should be same in both methods EncrypteBytes and DecrypteBytes. If both are not same, then it will generate the error.
My problem was I was taking the encryped output in bytes and converting it to a string. The string back to byte array (for decrypting) was not the same. I was using UTF8Encoding, then I tried ASCIIEnconding. Neither worked.
Convert.FromBase64String/ToBase64String worked fine, got rid of the padding issues and actually decrypted the data.
It's work
using (FileStream fs = new FileStream( absolute, FileMode.Open )) {
// create a CryptoStream in read mode
using (CryptoStream cryptoStream = new CryptoStream( fs, decryptor, CryptoStreamMode.Read )) {
int readLength = ( int )fs.Length;
byte[] buffer = new byte[readLength];
cryptoStream.Read( buffer, 0, readLength );
using (MemoryStream ms = new MemoryStream( buffer )) {
BinaryFormatter bf = new BinaryFormatter( );
settings = ( SettingsJson )bf.Deserialize( ms );// Deserialize SettingsJson array
}
}
fs.Close( );
}
I have 16 byte des encrypted data and i want to decrypt the problem is my routin only decrypt first 8 byte and for byte 9 it throw exception Bad Data my data has no padding exactly 16 byte of data
here is my code
public byte[] Decrypt(byte[] data)
{
List<byte> resData = new List<byte>();
try
{
DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider();
byte[] bytes = StringToByteArray(_key);
MemoryStream memoryStream = new MemoryStream(data);
CryptoStream cryptoStream = new CryptoStream(memoryStream, cryptoProvider.CreateDecryptor(bytes, new byte[8]), CryptoStreamMode.Read);
cryptoProvider.Padding = PaddingMode.None;
cryptoProvider.Mode = CipherMode.ECB;
BinaryReader reader = new BinaryReader(cryptoStream);
for (int i = 0; i < data.Length; i++)
{
resData.Add(reader.ReadByte());
}
}
catch { }
return resData.ToArray();
}
You need to set the properties on cryptoProvider before creating the crypter
No need to jump all those stream hoops, just call TransformFinalBlock
Your crypto is extremly weak. DES has a really small key-space and can be broken by brute-force.
An improved version of your code could look like this:
byte[] bytes = StringToByteArray(_key);
using(DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider())
{
cryptoProvider.Padding = PaddingMode.None;
cryptoProvider.Mode = CipherMode.ECB;
using(var crypter = cryptoProvider.CreateDecryptor(bytes, new byte[8]))
{
return crypter.TransformFinalBlock(bytes, 0, bytes.Length);
}
}
i have a code in c# that encrypt and decrypt .txt file. but i need to encrypt and decrypt files with any extension like pdf, zip, jpg etc..
i searched ant tried to find stream encryption but i couldnt find any..
i am trying following code from link . i changed file path and put some pdf or ppt. it works correctly but i can not open decrypted file.
using System;
using System.IO;
using System.Security;
using System.Security.Cryptography;
using System.Runtime.InteropServices;
using System.Text;
namespace CSEncryptDecrypt
{
class Class1
{
// Call this function to remove the key from memory after use for security
[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);
}
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();
}
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();
}
static void Main()
{
// Must be 64 bits, 8 bytes.
// Distribute this key to the user who will decrypt this file.
string sSecretKey;
// Get the Key for the file to Encrypt.
sSecretKey = GenerateKey();
// For additional security Pin the key.
GCHandle gch = GCHandle.Alloc( sSecretKey,GCHandleType.Pinned );
// Encrypt the file.
EncryptFile(#"C:\MyData.txt",
#"C:\Encrypted.txt",
sSecretKey);
// Decrypt the file.
DecryptFile(#"C:\Encrypted.txt",
#"C:\Decrypted.txt",
sSecretKey);
// Remove the Key from memory.
ZeroMemory(gch.AddrOfPinnedObject(), sSecretKey.Length * 2);
gch.Free();
}
}
}
thanks for responses. i found the reason. i should use filestream not the streamwriter in the decryptFile function
following routine I'm using to serialize objects securely.
Maybe it can help you to understand how stream encryption works:
public bool Save(string filename, object toSerialize)
{
byte[] SALT = new byte[]
{0x26, 0xdc, 0xff, 0x00, 0xad, 0xed, 0x7a, 0xee, 0xc5, 0xfe, 0x07, 0xaf, 0x4d, 0x08, 0x22, 0x3c};
string EncryptionKey = "MYPASSWORD";
//basic serialization
IFormatter form = new BinaryFormatter();
var stream = new MemoryStream();
form.Serialize(stream, toSerialize);
//cryptography preparation
var alg = new RijndaelManaged();
var pdb = new Rfc2898DeriveBytes(EncryptionKey, SALT);
alg.Key = pdb.GetBytes(32);
alg.IV = pdb.GetBytes(16);
stream.Position = 0;
//cryptorgraphy serialization
var encStream = new MemoryStream();
var cryptoStream = new CryptoStream(encStream, alg.CreateEncryptor(), CryptoStreamMode.Write);
cryptoStream.Write(stream.ToArray(), 0, (int)stream.Length);
cryptoStream.FlushFinalBlock();
var outputFileStream = new FileStream(fileName, FileMode.Create);
outputFileStream.Write(encStream.ToArray(), 0, (int)encStream.Length);
outputFileStream.Close();
return true;
}
I can also put you sources to deserialize encrypted stream.