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How can I encrypt this BinaryFormatter Save/Load methods in c#? [duplicate]

I'm studying encryption in C# and I'm having trouble. I have some Rijndael encryption code and it's working perfectly with strings. But now I'm studying serialization and the BinaryWriter writes the data of classes without any protection. I'm using this code to test; is there a way to "encrypt the class", or something similar?
To clarify the question, here is my code:
FileStream file = new FileStream(Environment.CurrentDirectory + #"\class.dat", FileMode.Create);
using (BinaryWriter sw = new BinaryWriter(file))
{
byte[] byt = ConverteObjectEmByte(myVarClass);
sw.Write(byt);
}
And this is how I read it:
MyClass newMyVarClass;
FileStream file = new FileStream(Environment.CurrentDirectory + #"\class.dat", FileMode.Open);
using (BinaryReader sr = new BinaryReader(file))
{
// 218 is the size of the byte array that I've tested (byt)
myNewVarClass = (MyClass)ConverteByteEmObject(sr.ReadBytes(218));
}
Thanks!

Rather than converting to byte[] as an intermediate step when passing to different stream objects you can chain multiple streams together, passing the output from one to the input of another.
This approach makes sense here, as you are chaining together
Binary Serialization => Encryption => Writing to File.
With this in mind, you can change ConvertObjectEmByte to something like:
public static void WriteObjectToStream(Stream outputStream, Object obj)
{
if (object.ReferenceEquals(null, obj))
{
return;
}
BinaryFormatter bf = new BinaryFormatter();
bf.Serialize(outputStream, obj);
}
and similarly, ConvertByteEmObject can become:
public static object ReadObjectFromStream(Stream inputStream)
{
BinaryFormatter binForm = new BinaryFormatter();
object obj = binForm.Deserialize(inputStream);
return obj;
}
To add in the encryption/decryption, we can write functions that create CryptoStream objects that we can chain with these binary serialization functions. My example functions below look a bit different from the Encrypt/Decrypt functions in the article you linked to because the IV (Initialization Vector) is now generated randomly and written to the stream (and read from the stream on the other end). It's important that the IV is unique for each chunk of data you encrypt for security, and you should also use a random number generator intended for cryptographic purposes like RNGCryptoServiceProvider, rather than a pseudo-random number generator like Random.
public static CryptoStream CreateEncryptionStream(byte[] key, Stream outputStream)
{
byte[] iv = new byte[ivSize];
using (var rng = new RNGCryptoServiceProvider())
{
// Using a cryptographic random number generator
rng.GetNonZeroBytes(iv);
}
// Write IV to the start of the stream
outputStream.Write(iv, 0, iv.Length);
Rijndael rijndael = new RijndaelManaged();
rijndael.KeySize = keySize;
CryptoStream encryptor = new CryptoStream(
outputStream,
rijndael.CreateEncryptor(key, iv),
CryptoStreamMode.Write);
return encryptor;
}
public static CryptoStream CreateDecryptionStream(byte[] key, Stream inputStream)
{
byte[] iv = new byte[ivSize];
if (inputStream.Read(iv, 0, iv.Length) != iv.Length)
{
throw new ApplicationException("Failed to read IV from stream.");
}
Rijndael rijndael = new RijndaelManaged();
rijndael.KeySize = keySize;
CryptoStream decryptor = new CryptoStream(
inputStream,
rijndael.CreateDecryptor(key, iv),
CryptoStreamMode.Read);
return decryptor;
}
Finally, we can glue it together:
byte[] key = Convert.FromBase64String(cryptoKey);
using (FileStream file = new FileStream(Environment.CurrentDirectory + #"\class.dat", FileMode.Create))
using (CryptoStream cryptoStream = CreateEncryptionStream(key, file))
{
WriteObjectToStream(cryptoStream, myVarClass);
}
MyClass newMyVarClass;
using (FileStream file = new FileStream(Environment.CurrentDirectory + #"\class.dat", FileMode.Open))
using (CryptoStream cryptoStream = CreateDecryptionStream(key, file))
{
newMyVarClass = (MyClass)ReadObjectFromStream(cryptoStream);
}
Note that we pass the file stream object to CreateEncryptionStream (and CreateDecryptionStream), and then pass the cryptoStream object to WriteObjectToStream (and ReadObjectfromStream). You'll also notice that the streams are scoped inside using blocks, so that they'll automatically be cleaned up when we're finished with them.
Here's the full test program:
using System;
using System.IO;
using System.Runtime.Serialization.Formatters.Binary;
using System.Security.Cryptography;
namespace CryptoStreams
{
class Program
{
[Serializable]
public class MyClass
{
public string TestValue
{
get;
set;
}
public int SomeInt
{
get;
set;
}
}
public static void WriteObjectToStream(Stream outputStream, Object obj)
{
if (object.ReferenceEquals(null, obj))
{
return;
}
BinaryFormatter bf = new BinaryFormatter();
bf.Serialize(outputStream, obj);
}
public static object ReadObjectFromStream(Stream inputStream)
{
BinaryFormatter binForm = new BinaryFormatter();
object obj = binForm.Deserialize(inputStream);
return obj;
}
private const string cryptoKey =
"Q3JpcHRvZ3JhZmlhcyBjb20gUmluamRhZWwgLyBBRVM=";
private const int keySize = 256;
private const int ivSize = 16; // block size is 128-bit
public static CryptoStream CreateEncryptionStream(byte[] key, Stream outputStream)
{
byte[] iv = new byte[ivSize];
using (var rng = new RNGCryptoServiceProvider())
{
// Using a cryptographic random number generator
rng.GetNonZeroBytes(iv);
}
// Write IV to the start of the stream
outputStream.Write(iv, 0, iv.Length);
Rijndael rijndael = new RijndaelManaged();
rijndael.KeySize = keySize;
CryptoStream encryptor = new CryptoStream(
outputStream,
rijndael.CreateEncryptor(key, iv),
CryptoStreamMode.Write);
return encryptor;
}
public static CryptoStream CreateDecryptionStream(byte[] key, Stream inputStream)
{
byte[] iv = new byte[ivSize];
if (inputStream.Read(iv, 0, iv.Length) != iv.Length)
{
throw new ApplicationException("Failed to read IV from stream.");
}
Rijndael rijndael = new RijndaelManaged();
rijndael.KeySize = keySize;
CryptoStream decryptor = new CryptoStream(
inputStream,
rijndael.CreateDecryptor(key, iv),
CryptoStreamMode.Read);
return decryptor;
}
static void Main(string[] args)
{
MyClass myVarClass = new MyClass
{
SomeInt = 1234,
TestValue = "Hello"
};
byte[] key = Convert.FromBase64String(cryptoKey);
using (FileStream file = new FileStream(Environment.CurrentDirectory + #"\class.dat", FileMode.Create))
{
using (CryptoStream cryptoStream = CreateEncryptionStream(key, file))
{
WriteObjectToStream(cryptoStream, myVarClass);
}
}
MyClass newMyVarClass;
using (FileStream file = new FileStream(Environment.CurrentDirectory + #"\class.dat", FileMode.Open))
using (CryptoStream cryptoStream = CreateDecryptionStream(key, file))
{
newMyVarClass = (MyClass)ReadObjectFromStream(cryptoStream);
}
Console.WriteLine("newMyVarClass.SomeInt: {0}; newMyVarClass.TestValue: {1}",
newMyVarClass.SomeInt,
newMyVarClass.TestValue);
}
}
}

I'm not sure whether the .Net Library had changed or just the code is wrong. I can't directly run the code written by softwariness.
Since that, I changed the code based on the answer so that it can be used correctly. Here's an example.
public class CryptoSerialization
{
public static void WriteObjectToStream(Stream outputStream, object obj)
{
if (obj is null) throw new ArgumentNullException("obj can't be null");
BinaryFormatter bf = new BinaryFormatter();
bf.Serialize(outputStream, obj);
}
public static object ReadObjectFromStream(Stream inputStream)
{
BinaryFormatter bf = new BinaryFormatter();
return bf.Deserialize(inputStream);
}
public static CryptoStream CreateEncryptionStream(Stream outputStream, byte[] Key, byte[] IV)
{
Rijndael rijndael = new RijndaelManaged();
return new CryptoStream(outputStream, rijndael.CreateEncryptor(Key, IV), CryptoStreamMode.Write);
}
public static CryptoStream CreateDecryptionStream(Stream inputStream, byte[] Key, byte[] IV)
{
Rijndael rijndael = new RijndaelManaged();
return new CryptoStream(inputStream, rijndael.CreateDecryptor(Key, IV), CryptoStreamMode.Read);
}
public static void EncryptObjectToFile(object obj, string path, byte[] Key, byte[] IV)
{
using FileStream file = new FileStream(path, FileMode.Create);
using (CryptoStream cryptoStream = CreateEncryptionStream(file, Key, IV))
{
WriteObjectToStream(cryptoStream, obj);
}
}
public static object DecryptObjectFromFile(string path, byte[] Key, byte[] IV)
{
using FileStream file = new FileStream(path, FileMode.Open);
using (CryptoStream cryptoStream = CreateDecryptionStream(file, Key, IV))
{
return ReadObjectFromStream(cryptoStream);
}
}
}
[Serializable]
public class Student
{
public string Name;
public int Age;
}
static async Task Main(string[] args)
{
// the original string "[This is an example key string!]";
// I don't know if the length of the string has to be 32, but when I tried 64, it went wrong.
string cryptoKey = "W1RoaXMgaXMgYW4gZXhhbXBsZSBrZXkgc3RyaW5nIV0=";
byte[] Key = Convert.FromBase64String(cryptoKey);
byte[] IV = new byte[16];
using (RNGCryptoServiceProvider rngcsp = new RNGCryptoServiceProvider())
{
rngcsp.GetBytes(IV);
}
//same as
//Rijndael rijndael = new RijndaelManaged();
//rijndael.GenerateIV();
//byte[] iv = rijndael.IV;
List<Student> students = new List<Student>() { new Student { Name = "John", Age = 10 }, new Student { Name = "Marry", Age = 15 } };
CryptoSerialization.EncryptObjectToFile(students, Environment.CurrentDirectory + #"\testCrypto.dat", Key, IV);
List<Student> newStudents = (List<Student>)CryptoSerialization.DecryptObjectFromFile(Environment.CurrentDirectory + #"\testCrypto.dat", Key, IV);
newStudents.ForEach((stu) =>
{
Console.WriteLine(stu.Name + ", " + stu.Age);
});
Console.ReadKey();
}

Error while decrypting file via AES in c#

I am building a application that can encrypt and decrypt files, in c#. The encryption seems like its working (I think its working) however the decryption gives me the exception "The input data is not a complete block." I have tried almost everything I could find online so I thought I should come here. Here is the decryption code:
static void decryptAES (/*byte[] buffer,*/string filePath,byte[] key, byte[] IV)
{
Console.WriteLine("1");
using (AesCryptoServiceProvider AES = new AesCryptoServiceProvider())
{
AES.Padding = PaddingMode.PKCS7;
AES.Key = key;
AES.BlockSize = 128;
AES.KeySize = 128;
AES.IV = IV;
using (FileStream fStream = new FileStream(filePath, FileMode.Open, FileAccess.ReadWrite))
{
using (ICryptoTransform crypt = AES.CreateDecryptor(key, IV))
{
using (CryptoStream crStream = new CryptoStream(fStream, crypt, CryptoStreamMode.Read))
{
using (StreamReader reader = new StreamReader(crStream))
{
//breaks here
string data = reader.ReadToEnd();
File.WriteAllText(filePath, data);
File.Move(filePath, filePath.Replace(".encrypted", ""));
}
}
}
}
}
}
It breaks on the line with the comment //breaks here by the way.
Thanks.
Here is the encrypt function
static void encryptAES(byte[] filesBytes,string
filePath,AesCryptoServiceProvider aes)
{
using (FileStream fStream = new FileStream(filePath, FileMode.Open, FileAccess.ReadWrite))
{
using (ICryptoTransform crypt = aes.CreateEncryptor(aes.Key, aes.IV))
{
using (CryptoStream csStream = new CryptoStream(fStream, crypt, CryptoStreamMode.Write))
{
csStream.Write(filesBytes, 0, filesBytes.Length);
}
try { File.Move(filePath, filePath + ".encrypted"); }
catch (UnauthorizedAccessException)
{
}
}
}
}
And here is the key generation:
static AesCryptoServiceProvider generateAES()
{
AesCryptoServiceProvider a = new AesCryptoServiceProvider();
a.Padding = PaddingMode.PKCS7;
a.BlockSize =128;
a.KeySize = 128;
a.GenerateIV();
a.GenerateKey();
return a;
}
Here is how I stored the IV and AES Key:
private static void dumpKeys(AesCryptoServiceProvider aes)
{
foreach (byte b in aes.Key)
{
Console.Write(b);
}
Console.WriteLine();
foreach (byte b in aes.IV)
{
Console.Write(b);
}
byte[] encryptedKey = encryptRSA(aes.Key);
byte[] encryptedIV = encryptRSA(aes.IV);
Directory.CreateDirectory(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData) + #"\Keys");
File.WriteAllBytes(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData) + #"\Keys\0000000000000.Key", encryptedKey);
File.WriteAllBytes(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData) + #"\Keys\1111111111111.IV", encryptedIV);
}
And here is how I retrieve the key and iv data:
byte[] AESKey = decrypt(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData) + #"\Keys\0000000000000.Key");
byte[] AESIV = decrypt(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData) + #"\Keys\1111111111111.IV");
static byte[] decrypt(string path)
{
using (RSACryptoServiceProvider RSA = new RSACryptoServiceProvider())
{
RSA.FromXmlString(Properties.Resources.privateKey);
byte[] unencrypted = RSA.Decrypt(File.ReadAllBytes(path), true);
foreach (byte b in unencrypted)
{
Console.Write(b);
}
Console.WriteLine();
return unencrypted;
}
}
Btw I store a public RSA key in my resources file and I use that to decrypt the key.
Thanks

So far, so good. Do you extract the generated Key and IV? I modified your decryption function to an encryption function...
public static void Main()
{
var f = #"q:\test.txt";
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, f, key, iv);
decryptAES(AES, f + ".encrypted", key, iv);
}
static 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);
}
}
}
}
}
static 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);
}
}
}
}
}

Tested it with your code, slightly modified (changed FileMode.Open to FileMode.OpenOrCreate, Added File.Delete before File.Move and merged File.WriteAllText with File.Move) and it works. So a) please review your code. b) If it still fails, provide more details, a single codeblock with every function and a Main-method that calls your functions to reproduce your failure...
static AesCryptoServiceProvider generateAES()
{
AesCryptoServiceProvider a = new AesCryptoServiceProvider();
a.Padding = PaddingMode.PKCS7;
a.BlockSize = 128;
a.KeySize = 128;
a.GenerateIV();
a.GenerateKey();
return a;
}
static void encryptAES(byte[] filesBytes, string filePath, AesCryptoServiceProvider aes)
{
using (FileStream fStream = new FileStream(filePath, FileMode.OpenOrCreate, FileAccess.ReadWrite))
{
using (ICryptoTransform crypt = aes.CreateEncryptor(aes.Key, aes.IV))
{
using (CryptoStream csStream = new CryptoStream(fStream, crypt, CryptoStreamMode.Write))
{
csStream.Write(filesBytes, 0, filesBytes.Length);
}
try {
File.Delete(filePath + ".encrypted");
File.Move(filePath, filePath + ".encrypted");
}
catch (UnauthorizedAccessException)
{
}
}
}
}
static void decryptAES(/*byte[] buffer,*/string filePath, byte[] key, byte[] IV)
{
using (AesCryptoServiceProvider AES = new AesCryptoServiceProvider())
{
AES.Padding = PaddingMode.PKCS7;
AES.Key = key;
AES.BlockSize = 128;
AES.KeySize = 128;
AES.IV = IV;
using (FileStream fStream = new FileStream(filePath, FileMode.Open, FileAccess.ReadWrite))
{
using (ICryptoTransform crypt = AES.CreateDecryptor(key, IV))
{
using (CryptoStream crStream = new CryptoStream(fStream, crypt, CryptoStreamMode.Read))
{
using (StreamReader reader = new StreamReader(crStream))
{
//breaks here
string data = reader.ReadToEnd();
File.WriteAllText(filePath.Replace(".encrypted", ""), data);
}
}
}
}
}
}

C# encrypt and decrypt generic List<T> [duplicate]

Here is my code:
public static void Save<T>(T toSerialize, string fileSpec) {
BinaryFormatter formatter = new BinaryFormatter();
DESCryptoServiceProvider des = new DESCryptoServiceProvider();
using (FileStream stream = File.Create(fileSpec)) {
using (CryptoStream cryptoStream = new CryptoStream(stream, des.CreateEncryptor(key, iv), CryptoStreamMode.Write)) {
formatter.Serialize(cryptoStream, toSerialize);
cryptoStream.FlushFinalBlock();
}
}
}
public static T Load<T>(string fileSpec) {
BinaryFormatter formatter = new BinaryFormatter();
DESCryptoServiceProvider des = new DESCryptoServiceProvider();
using (FileStream stream = File.OpenRead(fileSpec)) {
using (CryptoStream cryptoStream = new CryptoStream(stream, des.CreateEncryptor(key, iv), CryptoStreamMode.Read)) {
return (T)formatter.Deserialize(cryptoStream);
}
}
}
Key and iv are both static byte arrays with a length of 8 which I'm using for testing purposes. There error is as follows:
Binary stream '178' does not contain a valid BinaryHeader. Possible causes are invalid stream or object version change between serialization and deserialization
Any help is much appreciated!

One small typo: your Load method should use des.CreateDecryptor, like this:
public static T Load<T>(string fileSpec)
{
BinaryFormatter formatter = new BinaryFormatter();
DESCryptoServiceProvider des = new DESCryptoServiceProvider();
using (FileStream stream = File.OpenRead(fileSpec))
{
using (CryptoStream cryptoStream =
new CryptoStream(stream, des.CreateDecryptor(key, iv),
CryptoStreamMode.Read))
{
return (T)formatter.Deserialize(cryptoStream);
}
}
}

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.

The input data is not a complete block

Scenario: One symmetric key, each user has his own IV, the documents are stored in a NVARCHAR(MAX) field. When I try to to decrypt the file, I get:
The input data is not a complete block.
// Create symmetric key
public static byte[] CreateKey()
{
AesCryptoServiceProvider aesCrypto = (AesCryptoServiceProvider)AesCryptoServiceProvider.Create();
byte[] key = aesCrypto.Key;
return key;
}
//Get key (stored in a database)
public static Byte[] GetAppKey()
{
return db.Encryptors.Where(x => x.EncryptorID == 1).Single().EncryptionKey.ToArray();
}
// Get application IV (stored in database)
public static Byte[] GetAppIV()
{
return db.Encryptors.Where(x => x.EncryptorID == 1).Single().IV.ToArray();
}
// Encrypt document (this will be stored in a VARBINARY(MAX) field
public static byte[] EncryptBinaryToBytes(Binary document, byte[] iv)
{
byte[] key = GetAppKey();
byte[] encrypted;
using (AesCryptoServiceProvider aesCsp = new AesCryptoServiceProvider())
{
aesCsp.Key = key;
aesCsp.IV = iv;
ICryptoTransform encryptor = aesCsp.CreateEncryptor(aesCsp.Key, aesCsp.IV);
using (MemoryStream msEncrypt = new MemoryStream())
{
using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
{
using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
{
swEncrypt.Write(document);
}
encrypted = msEncrypt.ToArray();
}
}
}
// return the encrypted document
return encrypted;
}
// Decrypt document
public static byte[] DecryptBytesToBytes(byte[] document, byte[] iv)
{
byte[] key = GetAppKey();
using (AesCryptoServiceProvider aesCsp = new AesCryptoServiceProvider())
{
aesCsp.Key = key;
aesCsp.IV = iv;
ICryptoTransform decryptor = aesCsp.CreateDecryptor(aesCsp.Key, aesCsp.IV);
using (MemoryStream msDecrypt = new MemoryStream())
{
using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Write))
{
using (StreamWriter swDecrypt = new StreamWriter(csDecrypt))
{
swDecrypt.Write(document);
}
byte[] decrypted = msDecrypt.ToArray();
// return the unencrypted document
return decrypted;
}
}
}
}
Thanks in advance.
To store the document
byte[] fileByte = fluUploadFile.FileBytes;
Binary document = new Binary(fileByte);
byte[] appIv = AES.GetAppIV();
byte[] encryptedDocument = AES.EncryptBinaryToBytes(document, appIv);
byte[] decryptedDocument = AES.DecryptBytesToBytes(encryptedDocument, appIv);
Document d = new Document()
{
OriginalName = originalName,
DocSize = fileSize,
BinaryDocument = encryptedDocument,
UploadedName = uploadedFileName,
MimeType = MIMEType,
DocExtension = extension
};
db.Documents.InsertOnSubmit(d);
db.SubmitChanges();

It's really important that you change the data type of the database field to VARBINARY(MAX), that way you avoid issues with character encodings and byte combinations that cannot be interpreted as legal characters.
Also, I think the problem is that you are not closing the streams before calling ToArray() method on the MemoryStream in both encrypt and decrypt routines. It's very important to call Close() in the CryptoStream so that FlushFinalBlock() is called and the encryption process writes the final block to the stream.
Try moving the call to MemoryStream.ToArray() to the outer using block, that is, outside the using block of CryptoStream, so that Dispose() is called on the CryptoStream and call MemoryStream.Close() before that.
Another problem with your code is that you are wrapping the CryptoStream with a StreamWriter, which writes the text representation of the object you pass into the Write method. You should instead write directly to the CryptoStream to avoid any byte to string conversions.