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RijndaelManaged - Encrypt/Decrypt a Stream in C#

I am trying to encrypt and decrypt a stream (a PDF document at base), but I am having issues with this. When I try to open the document after decryption and download, I get the error Failed to load the PDF document.
Do you know why this might be happening?
Here is the code for encryption:
public EncryptResult EncryptStream(Stream dataStream, bool reuseIV = false)
{
RijndaelManaged crypto = new RijndaelManaged();
crypto.Key = _key;
if (!reuseIV || _iv == null)
{
// make a copy of the current IV
_iv = crypto.IV;
}
else
{
// reuse the previous IV
crypto.IV = _iv;
}
var result = new EncryptResult() { IV = crypto.IV };
using (var encryptor = crypto.CreateEncryptor())
{
using (MemoryStream msEncrypt = new MemoryStream())
{
using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
{
var byteArrayInput = new byte[dataStream.Length];
dataStream.Read(byteArrayInput, 0, byteArrayInput.Length);
csEncrypt.Write(byteArrayInput, 0, byteArrayInput.Length);
dataStream.Close();
result.Cipher = msEncrypt.ToArray();
msEncrypt.Flush();
msEncrypt.Position = 0;
return result;
}
}
}
}
and decryption:
public Stream DecryptStream(byte[] cipher, byte[] iv)
{
RijndaelManaged crypto = new RijndaelManaged();
crypto.Key = _key;
crypto.IV = iv;
crypto.Padding = PaddingMode.Zeros;
using (var decryptor = crypto.CreateDecryptor())
{
using (MemoryStream msDecrypt = new MemoryStream(cipher))
{
using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
{
var sOutputFilename = new MemoryStream();
var fsDecrypted = new StreamWriter(sOutputFilename);
fsDecrypted.Write(new StreamReader(csDecrypt).ReadToEnd());
sOutputFilename.Position = 0;
return sOutputFilename;
}
}
}
}
Thanks in advance.

using (MemoryStream msEncrypt = new MemoryStream())
{
using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
{
//var byteArrayInput = new byte[dataStream.Length];
//dataStream.Read(byteArrayInput, 0, byteArrayInput.Length);
//csEncrypt.Write(byteArrayInput, 0, byteArrayInput.Length);
dataStream.CopyTo(csEncrypt);
dataStream.Close();
//result.Cipher = msEncrypt.ToArray(); // not here - not flushed yet
//msEncrypt.Flush(); // don't need this
//msEncrypt.Position = 0;
}
result.Cipher = msEncrypt.ToArray();
return result;
}
and in the decryptor, get rid of all the StreamReader/StreamWriter stuff.
A PDF file is compressed, ie binary. But this is after the decryption so it can't be your error.
using (var decryptor = crypto.CreateDecryptor())
{
using (MemoryStream msDecrypt = new MemoryStream(cipher))
{
var outputStream = new MemoryStream();
using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
{
csDecrypt.CopyTo(outputStream );
}
outputStream .Position = 0;
return outputStream ;
}
}

One issue is, you are likely encrypting excess bytes at the end of your stream, you need to work out how many bytes are read or use
Stream.CopyTo Method
Reads the bytes from the current stream and writes them to another
stream.

Rijndael decryption returns weird ouput

I have used Rijndael Algorithm for Encryption and decryption.
The Decryption works fine when i do it with Encryption.
But when i try to do Decryption alone it returns something like this
J˿m"�e��c4�ħ�dB̵��Dq#W�.
Also i have used two buttons one is for encryption and another one is for decryption and called the methods when button clicks.
I cannot able to get any idea regarding why the output is returning like this. Even i used same convertion(UTF8 Encoding) for both methods.
Please help me to solve this problem.
Below is my code:
public partial class Form1 : Form
{
private RijndaelManaged myRijndael = new RijndaelManaged();
private int iterations;
private byte [] salt;
public Form1(string strPassword)
{
myRijndael.BlockSize = 128;
myRijndael.KeySize = 128;
myRijndael.IV = HexStringToByteArray("e84ad660c4721ae0e84ad660c4721ae0");
myRijndael.Padding = PaddingMode.PKCS7;
myRijndael.Mode = CipherMode.CBC;
iterations = 1000;
salt = System.Text.Encoding.UTF8.GetBytes("cryptography123example");
myRijndael.Key = GenerateKey(strPassword);
}
public string Encrypt(string strPlainText)
{
byte[] strText = new System.Text.UTF8Encoding().GetBytes(strPlainText);
MemoryStream ms = new MemoryStream();
ICryptoTransform transform = myRijndael.CreateEncryptor();
CryptoStream cs = new CryptoStream(ms, transform, CryptoStreamMode.Write);
cs.Write(strText, 0, strText.Length);
cs.FlushFinalBlock();
return Convert.ToBase64String(ms.ToArray());
}
public string Decrypt(string encryptedText)
{
var encryptedBytes = Convert.FromBase64String(encryptedText);
MemoryStream ms = new MemoryStream();
ICryptoTransform transform = myRijndael.CreateDecryptor();
CryptoStream cs = new CryptoStream(ms, transform, CryptoStreamMode.Write);
cs.Write(encryptedBytes, 0, encryptedBytes.Length);
return System.Text.Encoding.UTF8.GetString(ms.ToArray());
}
public static byte[] HexStringToByteArray(string strHex)
{
dynamic r = new byte[strHex.Length / 2];
for (int i = 0; i <= strHex.Length - 1; i += 2)
{
r[i / 2] = Convert.ToByte(Convert.ToInt32(strHex.Substring(i, 2), 16));
}
return r;
}
private byte[] GenerateKey(string strPassword)
{
Rfc2898DeriveBytes rfc2898 = new Rfc2898DeriveBytes(System.Text.Encoding.UTF8.GetBytes(strPassword), salt, iterations);
return rfc2898.GetBytes(128 / 8);
}
private void button1_Click(object sender, EventArgs e)
{
EncryptOutput.Text = Encrypt(EncryptInput.Text);
}
private void button2_Click(object sender, EventArgs e)
{
DecryptOutput.Text = Decrypt(DecryptInput.Text);
}
}

Try this code:
public string Encrypt(string strPlainText) {
byte[] strText = System.Text.Encoding.UTF8.GetBytes(strPlainText);
using (ICryptoTransform encryptor = myRijndael.CreateEncryptor())
using (MemoryStream input = new MemoryStream(strText))
using (MemoryStream output = new MemoryStream())
using (CryptoStream cs = new CryptoStream(output, encryptor, CryptoStreamMode.Write)) {
input.CopyTo(cs);
cs.FlushFinalBlock();
return Convert.ToBase64String(output.GetBuffer(), 0, (int)output.Length);
}
}
public string Decrypt(string encryptedText) {
byte[] encryptedBytes = Convert.FromBase64String(encryptedText);
using (ICryptoTransform decryptor = myRijndael.CreateDecryptor())
using (MemoryStream input = new MemoryStream(encryptedBytes))
using (MemoryStream output = new MemoryStream())
using (CryptoStream cs = new CryptoStream(input, decryptor, CryptoStreamMode.Read)) {
cs.CopyTo(output);
return System.Text.Encoding.UTF8.GetString(output.GetBuffer(), 0, (int)output.Length);
}
}
public static byte[] HexStringToByteArray(string strHex) {
var r = new byte[strHex.Length / 2];
for (int i = 0; i < strHex.Length; i += 2) {
r[i / 2] = byte.Parse(strHex.Substring(i, 2), NumberStyles.HexNumber);
}
return r;
}
Please, remember using the using pattern... And dynamic should be used only in very special cases.
Note that the Encrypt is doable with one less Stream, in a very similar way to the one you wrote it:
public string Encrypt(string strPlainText) {
byte[] strText = System.Text.Encoding.UTF8.GetBytes(strPlainText);
using (ICryptoTransform encryptor = myRijndael.CreateEncryptor())
using (MemoryStream output = new MemoryStream())
using (CryptoStream cs = new CryptoStream(output, encryptor, CryptoStreamMode.Write)) {
cs.Write(strText, 0, strText.Length);
cs.FlushFinalBlock();
return Convert.ToBase64String(output.GetBuffer(), 0, (int)output.Length);
}
}
but the Decrypt needs two Stream, because the CryptoStream needs a Stream as a parameter, containing the encrypted data, and it is easier to write its output (of which you don't know the exact lenth, thanks to padding) to another stream.

cs.FlushFinalBlock(); forgotten in Decrypt()? I just round-tripped a test string with your code once I fixed that

AES (rijndael) decryption

I have a Security class that Encode and Decode string, but when I try do decode - something going wrong.
Here is my Security class:
class Security
{
public static String encrypt(String imput, String key)
{
String cipherText;
var rijndael = new RijndaelManaged()
{
Key = Encoding.Unicode.GetBytes(key),
Mode = CipherMode.ECB,
BlockSize = 128,
Padding = PaddingMode.Zeros,
};
ICryptoTransform encryptor = rijndael.CreateEncryptor(rijndael.Key, null);
using (var memoryStream = new MemoryStream())
{
using (var cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write))
{
using (var streamWriter = new StreamWriter(cryptoStream))
{
streamWriter.Write(imput);
streamWriter.Flush();
}
cipherText = Convert.ToBase64String(memoryStream.ToArray());
}
}
return cipherText;
}
public static String decrypt(String imput, String key)
{
byte[] data = Convert.FromBase64String(imput);
String decrypted;
using (RijndaelManaged rijAlg = new RijndaelManaged())
{
rijAlg.Key = Encoding.UTF8.GetBytes(key);
rijAlg.Mode = CipherMode.ECB;
rijAlg.BlockSize = 128;
rijAlg.Padding = PaddingMode.Zeros;
ICryptoTransform decryptor = rijAlg.CreateDecryptor(rijAlg.Key, null);
using (MemoryStream msDecrypt = new MemoryStream(data))
{
using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
{
using (StreamReader srDecrypt = new StreamReader(csDecrypt))
{
decrypted = srDecrypt.ReadToEnd();
}
}
}
}
return decrypted;
}
}
In program.cs:
String A = Security.encrypt("text", "1234567891234567");
A = Security.decrypt(A, "1234567891234567");
Finaly it return something like that: �%����;\0�\a��f6 , but I need original string. Where I made a mistake?

Use the same encoding in both methods, either Encoding.Unicode or Encoding.UTF8

Encrypt large files in c#

Please help me modify this code to encrypt/decrypt in blocks instead of huge byte arrays! the code that converts the file and calls the encryption class is:
Console.Write("Enter File Path: ");
docPath = Console.ReadLine();
extension = docPath.Substring(docPath.IndexOf(".")).Trim();
byte[] binarydata = File.ReadAllBytes(docPath);
text = System.Convert.ToBase64String(binarydata, 0, binarydata.Length);
var Encrypted = AESCryptography.Encrypt(text, m.ToString(), extension);
using (FileStream fs = File.Create(docPath.Substring(0,docPath.IndexOf(".")) + ".aent"))
{
Byte[] info = new UTF8Encoding(true).GetBytes(Encrypted);
// Add some information to the file.
fs.Write(info, 0, info.Length);
}
And the class that does the actual encryption is this:
public static class AESCryptography
{
private const int keysize = 256;
public static string Encrypt(string plainText, string passPhrase, string extention)
{
byte[] plainTextBytes = Encoding.UTF8.GetBytes(plainText);
using (PasswordDeriveBytes password = new PasswordDeriveBytes(passPhrase, null))
{
byte[] keyBytes = password.GetBytes(keysize / 8);
using (RijndaelManaged symmetricKey = new RijndaelManaged())
{
symmetricKey.GenerateIV();
symmetricKey.Mode = CipherMode.CBC;
using (ICryptoTransform encryptor = symmetricKey.CreateEncryptor(keyBytes, symmetricKey.IV))
{
using (MemoryStream memoryStream = new MemoryStream())
{
using (CryptoStream cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write))
{
cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);
cryptoStream.FlushFinalBlock();
byte[] cipherTextBytes = memoryStream.ToArray();
return Convert.ToBase64String(cipherTextBytes) + "\n" + Convert.ToBase64String(symmetricKey.IV) + "\n" + extention;
}
}
}
}
}
}
public static string Decrypt(string cipherText, string passPhrase, string initVector)
{
byte[] initVectorBytes = Convert.FromBase64String(initVector);
byte[] cipherTextBytes = Convert.FromBase64String(cipherText);
using (PasswordDeriveBytes password = new PasswordDeriveBytes(passPhrase, null))
{
byte[] keyBytes = password.GetBytes(keysize / 8);
using (RijndaelManaged symmetricKey = new RijndaelManaged())
{
symmetricKey.Mode = CipherMode.CBC;
using (ICryptoTransform decryptor = symmetricKey.CreateDecryptor(keyBytes, initVectorBytes))
{
using (MemoryStream memoryStream = new MemoryStream(cipherTextBytes))
{
using (CryptoStream cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read))
{
byte[] plainTextBytes = new byte[cipherTextBytes.Length];
int decryptedByteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);
return Encoding.UTF8.GetString(plainTextBytes, 0, decryptedByteCount);
}
}
}
}
}
}
}
I need the encryption class to be able to encrypt files as big as ~2.5GB.
I have tried multiple times, most didn't work others didn't even encrypt!
Please Help! I need to present this tomorrow!

You can 'chain' streams to encrypt large files, so you don't need to hold them in memory.
See answer from anton-gogolev https://stackoverflow.com/a/38629596/1776231 for question AES-Encrypt-then-MAC a large file with .NET
using(var encryptedFileStream = File.OpenWrite("..."))
using(var macCryptoStream = new CryptoStream(encryptedFileStream, mac, CryptoStreamMode.Write))
using(var encryptCryptoStream = new CryptoStream(macCryptoStream, encryptor, CryptoStreamMode.Write))
using(var inputFileStream = File.OpenRead("..."))
inputFileStream.CopyTo(encryptCryptoStream);

deserialization c#

I have a WPF application contains this class:*
{[Serializable]
public class Parametres
{
private string admin_login;
private string admin_pwd;
private string server;
private string db;
private string user;
private string pwd;}
i serialize an object with this function:
public static void Serialize_Parametres(string filename, Parametres obj)
{
using (FileStream fs = File.Open(filename, FileMode.OpenOrCreate))
{
using (CryptoStream cs = new CryptoStream(fs, key.CreateEncryptor(), CryptoStreamMode.Write))
{
XmlSerializer xmlser = new XmlSerializer(typeof(Parametres));
xmlser.Serialize(cs, obj);
}
}
}
it's works fine and it generates a file .txt , but when i try to deserialize this file and get the object parametres whith this function:
public static Parametres DeSerialize_Parametres(string filename)
{
using (FileStream fs = File.Open(filename, FileMode.Open))
{
using (CryptoStream cs = new CryptoStream(fs, key.CreateDecryptor(), CryptoStreamMode.Read))
{
XmlSerializer xmlser = new XmlSerializer(typeof(Parametres));
return (Parametres)xmlser.Deserialize(cs);
}
}
}
i got this error Length of the data to decrypt is invalid in the line return (Parametres)xmlser.Deserialize(cs);
What is exactly the reason of this error? how can i fix it?

When using this techique to serialize an object you have to do in two parts. The length encrypted stream must be stored as part of the final stream and its up to you to do this. However, you should break this up into a more resuable form.
For example, first serialze the graph you want into a byte stream; then
Encrypte the byte stream; then
Save it to a file.
Below is an example on how to Serialize to a file using AES:
public class ObjectXmlSerializer
{
//---------------------------------------------------------------------
public override Byte[] Serialize(Object obj)
{
using (MemoryStream ms = new MemoryStream())
{
new XmlSerializer(obj.GetType()).Serialize(ms, obj);
return ms.ToArray();
}
}
//---------------------------------------------------------------------
public override T Deserialize<T>(Byte[] bObj)
{
using (MemoryStream ms = new MemoryStream(bObj))
{
return (T)new XmlSerializer(typeof(T)).Deserialize(ms);
}
}
//---------------------------------------------------------------------
public override T Deserialize<T>(Stream iostream)
{
return (T)new XmlSerializer(typeof(T)).Deserialize(iostream);
}
}
// next
public static class CryptoSerivces
{
//---------------------------------------------------------------------
public static Byte[] AesEncrypt(Byte[] src, Byte[] key, Byte[] IV)
{
using (RijndaelManaged myRijndael = new RijndaelManaged())
{
try
{
myRijndael.Mode = CipherMode.CBC;
myRijndael.Key = key;
myRijndael.IV = IV;
myRijndael.Padding = PaddingMode.PKCS7;
using (ICryptoTransform encryptor = myRijndael.CreateEncryptor())
using (MemoryStream msEncrypt = new MemoryStream())
using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
{
csEncrypt.Write(src, 0, src.Length);
csEncrypt.FlushFinalBlock();
return msEncrypt.ToArray();
}
}
finally
{
myRijndael.Clear();
}
}
}
//---------------------------------------------------------------------
public static Byte[] AesDecrypt(Byte[] src, Byte[] key, Byte[] IV)
{
using (RijndaelManaged myRijndael = new RijndaelManaged())
{
try
{
myRijndael.Mode = CipherMode.CBC;
myRijndael.Key = key;
myRijndael.IV = IV;
myRijndael.Padding = PaddingMode.PKCS7;
using (ICryptoTransform decryptor = myRijndael.CreateDecryptor())
using (MemoryStream msDecrypt = new MemoryStream())
using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Write))
{
csDecrypt.Write(src, 0, src.Length);
csDecrypt.FlushFinalBlock();
return msDecrypt.ToArray();
}
}
finally
{
myRijndael.Clear();
}
}
}
}
// put all the peices together
void SaveToFile(String fileName, Parametres obj)
{
ObjectXmlSerializer oxs = new ObjectXmlSerializer();
Byte[] bObj = oxs.Serialize(obj);
Byte[] bEncObj = CryptoSerivces.AesEncrypt(bObj, SomeKey, SomeIV);
using (FileStream fs = File.Open(filename, FileMode.OpenOrCreate))
{
fs.Write(bEncObj, 0, bEncObj.Length);
}
}
// I'll leave the reading up to you.