I have used this code in the past for writing and reading xml files. This time I want to write some encrypted generated XML and then read it and process it internally. I will post the code and perhaps someone can spot the problem.
When I am testing the decrypt I have been able to output a file that has a continuous line of null character codes. The encrypted file seems to contain data and varys in size with different amounts of data.
Please help, thanks!
Encrypt
MemoryStream ms = new MemoryStream();
XmlTextWriter xmlwriter = new XmlTextWriter(ms,Encoding.UTF8);
FileStream EncryptedFileStream = new FileStream(file, FileMode.Create, FileAccess.Write);
DESCryptoServiceProvider DES = new DESCryptoServiceProvider();
DES.Key = ASCIIEncoding.ASCII.GetBytes("AAAAAAAA");
DES.IV = ASCIIEncoding.ASCII.GetBytes("AAAAAAAA");
ICryptoTransform desEncrypt = DES.CreateEncryptor();
CryptoStream cryptostream = new CryptoStream(EncryptedFileStream, desEncrypt, CryptoStreamMode.Write);
/*create working and tested XML data here*/
byte[] bytearray = new byte[ms.Length];
ms.Read(bytearray, 0, bytearray.Length);
cryptostream.Write(bytearray, 0, bytearray.Length);
cryptostream.Close();
EncryptedFileStream.Close();
xmlwriter.Close();
ms.Flush();
ms.Close();
DECRYPT
MemoryStream ms = new MemoryStream();
StreamWriter swDecrypt = new StreamWriter(ms);
DESCryptoServiceProvider DES = new DESCryptoServiceProvider();
DES.Key = ASCIIEncoding.ASCII.GetBytes("AAAAAAAA");
DES.IV = ASCIIEncoding.ASCII.GetBytes("AAAAAAAA");
ICryptoTransform desDecrypt = DES.CreateDecryptor();
FileStream fsDecrypt = new FileStream(mstrIndexFile, FileMode.Open, FileAccess.Read);
CryptoStream cryptostreamDecr = new CryptoStream(fsDecrypt, desDecrypt, CryptoStreamMode.Read);
swDecrypt.Write(new StreamReader(cryptostreamDecr).ReadToEnd());
swDecrypt.Flush();
ms.Position = 0;
Using your current architecture, you need to use the MemoryStream that you just filled with data (not forgetting to reset its position to zero and to flush any pending writes)
//I am currently stuck on this point.
swDecrypt.Flush();
ms.Position=0;
XmlTextReader lxmlReader = new XmlTextReader(ms);
however, my feeling is that you don't need a MemoryStream here. Instead, just supply the CryptoStream to the XmlTextReader:
CryptoStream cryptostreamDecr = new CryptoStream(.....
XmlTextReader lxmlReader = new XmlTextReader(cryptostreamDecr);
After much trial and error I was pointed to XML element encryption using the first method on the page. This method was much easier and straight forward. If anyone decides to use this just make sure you use the same KEY and IV on your encryption and decryption if they are taking place in separate places.
Basically, a copy paste operation and you can encrypt your entire document by passing in the root element!
-Feelsgoodman
Related
I've been fighting with chained using statements, and am unable to resolve the latest in a long line of implementation issues. I need to compress, then encrypt and append the generated IV to the selected file. This all appears to work correctly, however i'm unable to unwind the process. After looking at several similar stack postings and articles i'm still unable to get it to work and am now after more direct assistance.
The latest thrown error is System.IO.InvalidDataException: 'Found invalid data while decoding.' It appears that the decryption stream isn't functioning as intended and that's throwing the decompression stream out of wack.
byte[] key;
byte[] salt;
const int keySize = 256;
const int blockSize = keySize;
byte[] iv = new byte[blockSize / 8];//size to bits
RijndaelManaged rjndl;
RNGCryptoServiceProvider cRng;
void InitializeCryptor() {
//Temporarily define the salt & key
salt = Encoding.UTF8.GetBytes("SaltShouldBeAtLeast8Bytes");
key = new Rfc2898DeriveBytes("MyL0ngPa$$phra$e", salt, 4).GetBytes(keySize / 8);
//Initialize the crypto RNG generator
cRng = new RNGCryptoServiceProvider();
// Create instance of Rijndael (AES) for symetric encryption of the data.
rjndl = new RijndaelManaged();
rjndl.KeySize = keySize;
rjndl.BlockSize = blockSize;
rjndl.Mode = CipherMode.CBC;
}
void CompressAndEncryptFile(string relativeFilePath, string fileName) {
//Create a unique IV each time
cRng.GetBytes(iv);
//Create encryptor
rjndl.Key = key;
rjndl.IV = iv;
ICryptoTransform encryptor = rjndl.CreateEncryptor(rjndl.Key, rjndl.IV);
//Create file specific output sub-directory
Directory.CreateDirectory(Path.Combine(outputPath, relativeFilePath));
//Read and compress file into memory stream
using (FileStream readStream = File.OpenRead(Path.Combine(initialpath, relativeFilePath, fileName)))
using (FileStream writeStream = new FileStream(Path.Combine(outputPath, relativeFilePath, fileName + ".dat"), FileMode.Create))
using (CryptoStream encryptStream = new CryptoStream(writeStream, encryptor, CryptoStreamMode.Write))
using (DeflateStream compStream = new DeflateStream(encryptStream, CompressionLevel.Optimal)) {
//Write the following to the FileStream for the encrypted file:
// - length of the IV
// - the IV
byte[] ivSize = BitConverter.GetBytes(rjndl.IV.Length);
writeStream.Write(ivSize, 0, 4);
writeStream.Write(rjndl.IV, 0, rjndl.BlockSize / 8);
readStream.CopyTo(compStream);
}
}
void DecryptAndDecompressFile(string relativeFilePath) {
string outputPath = Path.Combine(initialpath, "Unpack");
Directory.CreateDirectory(outputPath);
using (FileStream readStream = new FileStream(Path.Combine(initialpath, manifestData.version, relativeFilePath + ".dat"), FileMode.Open)) {
byte[] tmpLength = new byte[4];
//Read length of IV
readStream.Seek(0, SeekOrigin.Begin);
readStream.Read(tmpLength, 0, 3);
int ivLength = BitConverter.ToInt32(tmpLength, 0);
byte[] readIv = new byte[ivLength];
//Read IV
readStream.Seek(4, SeekOrigin.Begin);
readStream.Read(readIv, 0, ivLength);
rjndl.IV = readIv;
//Start at beginning of encrypted data
readStream.Seek(4 + ivLength, SeekOrigin.Begin);
//Create decryptor
ICryptoTransform decryptor = rjndl.CreateEncryptor(key, readIv);
using (CryptoStream decryptStream = new CryptoStream(readStream, decryptor, CryptoStreamMode.Read))
using (DeflateStream decompStream = new DeflateStream(decryptStream, CompressionMode.Decompress))
using (FileStream writeStream = new FileStream(Path.Combine(outputPath, relativeFilePath), FileMode.Create)) {
decompStream.CopyTo(writeStream);
}
}
}
For those who like to point to other similar stack questions and vote to close/duplicate without offering support, the following are the threads, and posts I've worked through first, each without success.
https://learn.microsoft.com/en-us/dotnet/standard/security/walkthrough-creating-a-cryptographic-application
https://learn.microsoft.com/en-us/dotnet/api/system.security.cryptography.rijndaelmanaged?redirectedfrom=MSDN&view=netcore-3.1
Chained GZipStream/DeflateStream and CryptoStream (AES) breaks when reading
DeflateStream / GZipStream to CryptoStream and vice versa
https://learn.microsoft.com/en-us/dotnet/api/system.io.compression.gzipstream?redirectedfrom=MSDN&view=netcore-3.1#code-snippet-2
How to fix 'Found invalid data while decoding.'
Compression/Decompression string with C#
After ~2 days of investigating, i located my error.
I was calling rjndl.CreateEncryptor instead of rjndl.CreateDecryptor during the decryption portion... (Please tell me this type of $#!t happens to others too)
Once i finish testing i'll update my question code to serve as a nice example for anyone who lands here via google in the future.
I made the following code to insert data to an encrypted xml file, I used a memory stream for the decrypted file and load it in a XmlDocument to add the required data, then encrypted it again back to the same file.
public static void IN_EncryptFile(MemoryStream FLin,string Path)
{
UnicodeEncoding UE = new UnicodeEncoding();
byte[] key = UE.GetBytes(sKey);
string cryptFile = Path;
FileStream fsCrypt = new FileStream(cryptFile, FileMode.Open);
RijndaelManaged RMCrypto = new RijndaelManaged();
CryptoStream cs = new CryptoStream(fsCrypt,
RMCrypto.CreateEncryptor(key, key),
CryptoStreamMode.Write);
FLin.Position = 0;
int data;
while ((data = FLin.ReadByte()) != -1)
{
cs.WriteByte((byte)data);
}
FLin.Close();
FLin.Flush();
cs.Close();
fsCrypt.Close();
}
public static MemoryStream OUT_DecryptFile(string Path)
{
UnicodeEncoding UE = new UnicodeEncoding();
byte[] key = UE.GetBytes(sKey);
FileStream fsCrypt = new FileStream(Path, FileMode.Open);
RijndaelManaged RMCrypto = new RijndaelManaged();
CryptoStream cs = new CryptoStream(fsCrypt,
RMCrypto.CreateDecryptor(key, key),
CryptoStreamMode.Read);
MemoryStream fsOut = new MemoryStream();
int data;
while ((data = cs.ReadByte()) != -1)
fsOut.WriteByte((byte)data);
cs.Close();
fsCrypt.Close();
fsOut.Position = 0;
return fsOut;
}
public static void Add_Data_XML()
{
string XML_Pt = #"C:\Test.Trr";
XmlDocument XDt = new XmlDocument();
XDt.Load(Cryption.OUT_DecryptFile(XML_Pt));
/// Adding XMl data
MemoryStream Fnl = new MemoryStream();
XDt.Save(Fnl);
Cryption.IN_EncryptFile(Fnl, XML_Pt);
Fnl.Flush();
Fnl.Close();
}
I need an opinion about the code as it works fine for me but sometimes it generates some errors in the encrypted file which I still don't fully understand why, but when I dencrypt the xml file I find the added data are in the wrong format and placed after the main XMl node as follow :
<Main_Node>
</Main_Node>”ÇÛÏ”ö8—´Ú·…ï/1Ž"‹ÓÃåõ¶—QÝUŸy…¤Êç‹íîzR߆ô
nÃFçiŽÌm–FÆzÍW9 úv¤ï_øVO,ÈvÄ
Your issue is that you use MemoryStream to store the temporary data and you read from it while you can. MemoryStream has an internal buffer that is larger than the data you write to it usually. So if you keep reading from it, you may get garbage data out from it. I would recommend not reading byte by byte from it, or at least get the actual length of the data and read that many bytes.
You also first close the MemoryStream and then flush it. This is pointless.
Another problem could be because you use FileMode.Open and write less than the previously existed in the file. This will leave existing data after what you write and that will show as garbage. Using FileMode.Create would be the right way here, since it means "if there is no file with this name, create a new one. If there is a file, truncate it."
FileMode documentation
But if you surely always write more than you read, then this shouldn't be an issue.
Also I wouldn't say "it works fine for me" if it actually has issues.
I think you have an encoding issue. Try this
MemoryStream ms = new MemoryStream();
XDt.Save(ms);
StreamReader Fnl = new StreamReader(ms, Encoding.UTF8);
I'm using some code like this to encrypt a file.
FileStream fsInput = new FileStream(ifile_path,
FileMode.Open,
FileAccess.Read);
FileStream fsEncrypted = new FileStream(ofile_path,
FileMode.Create,
FileAccess.Write);
AesCryptoServiceProvider AES = new AesCryptoServiceProvider();
AES.Mode = CipherMode.CBC;
AES.KeySize = 256;
iv = AES.IV;
AES.Key = key;
ICryptoTransform aesencrypt = AES.CreateEncryptor();
CryptoStream cryptostream = new CryptoStream(fsEncrypted,
aesencrypt,
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();
However, while this code successfully encrypts .txt and .xml files, it doesn't work on other file types such as .docx, or image file formats. What changes can I make to the code to extend the functionality to all such file types?
You want to use a BinaryReader and BinaryWriter for doing the file I/O. The normal StreamReader will attempt to read the bytes using a particular encoding as it implements TextReader and will mangle primitive data types. This is why plain text .txt and .xml work while .docx files do not.
I want to save my DataTable in a file so that nobody can read it:
private DataTable machineTable = new DataTable();
private Rijndael crypto = Rijndael.Create();
private FileStream stream;
...
this.crypto.IV = ASCIIEncoding.ASCII.GetBytes(IV);
this.crypto.Key = ASCIIEncoding.ASCII.GetBytes(password);
this.stream = new FileStream(Global.MachineParametersDataFile, FileMode.OpenOrCreate, FileAccess.Write);
CryptoStream cryptoStream = new CryptoStream(this.stream, crypto.CreateEncryptor(this.crypto.Key, this.crypto.IV), CryptoStreamMode.Write);
this.machineTable.WriteXml(stream, XmlWriteMode.WriteSchema, true);
password: 32
byte IV: 16byte
My code produced a couple of binary lines, but the whole rest is completely unencrypted.
You're writing to the stream not the cryptoStream.
this.machineTable.WriteXml(cryptoStream, XmlWriteMode.WriteSchema, true);
I'm writing an application to Encrtpt/Decrypt files and using DESCryptoServiceProvider for this purpose. This seems to work for text files but when I use the same application for .xlsx file, the resulting encrypted file and the decrypted file get corrupted and I'm not able to open that any more. is there any way I can encryt / decrypt different kinds of file like .doc..xls etc.
update : added code for encryption/decryption
public static void EncryptFile(string filepath,string fileOutput, string key)
{
FileStream fsInput = new FileStream(filepath, FileMode.Open, FileAccess.Read);
FileStream fsEncrypted = new FileStream(fileOutput, FileMode.Create, FileAccess.Write);
DESCryptoServiceProvider DESc = new DESCryptoServiceProvider();
DESc.Key = ASCIIEncoding.ASCII.GetBytes(key);
DESc.IV = ASCIIEncoding.ASCII.GetBytes(key);
ICryptoTransform desEncrypt = DESc.CreateEncryptor();
CryptoStream cryptoStream = new CryptoStream(fsEncrypted, desEncrypt, CryptoStreamMode.Write);
byte[] byteArrayInput = new byte[fsInput.Length - 1];
fsInput.Read(byteArrayInput, 0, byteArrayInput.Length);
cryptoStream.Write(byteArrayInput, 0, byteArrayInput.Length);
cryptoStream.Close();
fsInput.Close();
fsEncrypted.Close();
}
public static void DecryptFile(string filepath, string fileOutput, string key)
{
DESCryptoServiceProvider DESc = new DESCryptoServiceProvider();
DESc.Key = ASCIIEncoding.ASCII.GetBytes(key);
DESc.IV = ASCIIEncoding.ASCII.GetBytes(key);
FileStream fsread = new FileStream(filepath, FileMode.Open, FileAccess.Read);
ICryptoTransform desDecrypt = DESc.CreateDecryptor();
CryptoStream cryptoStreamDcr = new CryptoStream(fsread, desDecrypt, CryptoStreamMode.Read);
StreamWriter fsDecrypted = new StreamWriter(fileOutput);
fsDecrypted.Write(new StreamReader(cryptoStreamDcr).ReadToEnd());
fsDecrypted.Flush();
fsDecrypted.Close();
}
static void Main(string[] args)
{
EncryptFile(#"C:\test1.xlsx", #"c:\test2.xlsx", "ABCDEFGH");
DecryptFile(#"C:\test2.xlsx", #"c:\test3.xlsx", "ABCDEFGH");
}
You are not encrypting or decrypting correctly. Encrypt -> Decrypt will always give a file identical to the input. If you post your code we may be able to assist in finding the bug in it.
You should use FileStreama as suggested in one of the comments by Kieren Johnstone. Also, you're not flushing the streams when encrypting - this may not be done automatically, so you should try and flush the streams, too.