private void DecryptFile(string inFile, string ext)
{
start = DateTime.Now;
Logger("Dec: Started on " + start.ToString("dd.MM.yyyy 'at' HH:mm:ss"));
int startFileName = inFile.LastIndexOf("\\") + 1;
string shortFileName = inFile.Substring(startFileName, inFile.LastIndexOf(".") - startFileName) + ext;
//string shortFileName = inFile.Substring(0, inFile.LastIndexOf(".")) + ext;
string labelText = "Decrypting file \"" + shortFileName + "\"";
// Create instance of Rijndael for
// symetric decryption of the data.
RijndaelManaged rjndl = new RijndaelManaged();
rjndl.KeySize = 256;
rjndl.BlockSize = 256;
rjndl.Mode = CipherMode.CBC;
// Create byte arrays to get the length of
// the encrypted key and IV.
// These values were stored as 4 bytes each
// at the beginning of the encrypted package.
byte[] LenK = new byte[4];
byte[] LenIV = new byte[4];
// Consruct the file name for the decrypted file.
string outFile = DecrFolder + shortFileName.Substring(0, shortFileName.LastIndexOf(".") - 1) + ext;
// make sure directory exist
try {
Directory.CreateDirectory(DecrFolder);
}
catch (Exception ex)
{
MessageBox.Show("Cannot create directory .\\Decrypt\r\n" + ex.Message);
return;
}
// Use FileStream objects to read the encrypted
// file (inFs) and save the decrypted file (outFs).
try {
using (FileStream inFs = new FileStream(inFile, FileMode.Open, FileAccess.Read, FileShare.Read, 8388608))
{
inFs.Seek(0, SeekOrigin.Begin);
inFs.Seek(0, SeekOrigin.Begin);
inFs.Read(LenK, 0, 3);
inFs.Seek(4, SeekOrigin.Begin);
inFs.Read(LenIV, 0, 3);
// Convert the lengths to integer values.
int lenK = BitConverter.ToInt32(LenK, 0);
int lenIV = BitConverter.ToInt32(LenIV, 0);
int lenHash = 32;
// Create the byte arrays for
// the encrypted Rijndael key,
// the IV, and the hash.
byte[] KeyEncrypted = new byte[lenK];
byte[] IV = new byte[lenIV];
byte[] hashRead = new byte[lenHash];
// Extract the key, IV and hash
// starting from index 8
// after the length values.
inFs.Seek(8, SeekOrigin.Begin);
inFs.Read(KeyEncrypted, 0, lenK);
inFs.Seek(8 + lenK, SeekOrigin.Begin);
inFs.Read(IV, 0, lenIV);
inFs.Seek(8 + lenK + lenIV, SeekOrigin.Begin);
inFs.Read(hashRead, 0, lenHash);
Logger("Dec: hash declared = " + BitConverter.ToString(hashRead));
// check hash
// construct key for HMACSHA provider
byte[] hashKey = new byte[lenIV + 4];
IV.CopyTo(hashKey, 0);
byte[] pad = BitConverter.GetBytes(9);
pad.CopyTo(hashKey, (hashKey.Length - 4));
// make and compare hash
using (HMACSHA256 hmac = new HMACSHA256(hashKey))
{
// set position in stream
long dataIndex = LenK.Length + LenIV.Length + lenK + lenIV + lenHash;
inFs.Seek(dataIndex, SeekOrigin.Begin);
labelText = "Checking file integrity, please wait...";
backgroundWorker1.ReportProgress(0, labelText);
// generate hash
byte[] computedHash = hmac.ComputeHash(inFs);
Logger("Dec: hash computed = " + BitConverter.ToString(computedHash));
try
{
bool isHashOK = Enumerable.SequenceEqual(hashRead, computedHash);
if (!isHashOK)
{
backgroundWorker1.ReportProgress(-1);
Logger("Dec: hashes does not match");
labelText = "Cannot decrypt file. Integrity check ended up with false";
backgroundWorker1.ReportProgress(0, labelText);
throw new Exception("Cannot guarantee file integrity.\r\n" +
"Integrity check ended up with false"
);
}
}
catch (Exception e)
{
MessageBox.Show(e.Message);
return;
}
Logger("Dec: hash OK");
labelText = "Decrypting file \"" + shortFileName + "\"";
backgroundWorker1.ReportProgress(0, labelText);
}
// Use RSACryptoServiceProvider
// to decrypt the Rijndael key.
byte[] KeyDecrypted;
try {
KeyDecrypted = rsa.Decrypt(KeyEncrypted, false);
}
catch (CryptographicException ce)
{
backgroundWorker1.ReportProgress(0, "Cannot decrypt file \"" + shortFileName + "\" with given key.");
inFs.Dispose();
backgroundWorker1.ReportProgress(-1);
MessageBox.Show("Data integrity is OK, but cannot decrypt!\r\nYou have probably wrong key!\r\nOfficial cause: " + ce.Message);
return;
}
// Decrypt the key.
ICryptoTransform transform = rjndl.CreateDecryptor(KeyDecrypted, IV);
// Determine the start postition of
// the ciphter text (startC)
// and its length(lenC).
int startC = LenK.Length + LenIV.Length + lenK + lenIV + lenHash;
int lenC = (int)inFs.Length - startC;
// Decrypt the cipher text from
// from the FileSteam of the encrypted
// file (inFs) into the FileStream
// for the decrypted file (outFs).
using (FileStream outFs = new FileStream(outFile, FileMode.Create))
{
int count = 0;
// blockSizeBytes can be any arbitrary size.
int blockSizeBytes = rjndl.BlockSize / 8;
byte[] data = new byte[blockSizeBytes];
// By decrypting a chunk a time,
// you can save memory and
// accommodate large files.
// Start at the beginning
// of the cipher text.
inFs.Seek(startC, SeekOrigin.Begin);
using (CryptoStream outStreamDecrypted = new NotClosingCryptoStream(outFs, transform, CryptoStreamMode.Write))
{
double fileLength = lenC;//inFs.Length;
double blocks = fileLength / blockSizeBytes;
int step = (int)Math.Ceiling(blocks) / 128;
if (step < 1)
{
step = 1;
}
int iteration = 1;
do
{
count = inFs.Read(data, 0, blockSizeBytes);
outStreamDecrypted.Write(data, 0, count);
if (iteration++ % step == 0)
{
backgroundWorker1.ReportProgress(1); //increment progressBar and NOT change label1
}
}while (count > 0);
backgroundWorker1.ReportProgress(100); //set 100% full progress bar due to very small files
}//CryptoStream
Logger("Dec: Decrypted file length = " + outFs.Length);
outFs.Close();
}//outFs
inFs.Close();
labelText = "Decryption of \"" + shortFileName + "\" was succesful";
backgroundWorker1.ReportProgress(0, labelText);
Logger("Dec: Decryption was succesful");
finish = DateTime.Now;
TimeSpan duration = finish.Subtract(start);
Logger("Dec: Finished on " + finish.ToString("dd.MM.yyyy 'at' HH:mm:ss"));
Logger("File \"" + inFile + "\"\r\n decrypted in " +
duration.Days + " days, " +
duration.Hours + ":" +
duration.Minutes + ":" + duration.Seconds +
"." + duration.Milliseconds +
"\r\n=================================================="
);
}
}
catch (Exception exc)
{
backgroundWorker1.ReportProgress(-1);
backgroundWorker1.ReportProgress(0, "Error occured in decrypt process");
MessageBox.Show("Error occured in decrypt process" + exc.GetType() + "\r\n" + exc.Message);
}
}
private void EncryptFile(string inFile, string ext)
{
start = DateTime.Now;
Logger("Enc: Started on " + start.ToString("dd.MM.yyyy 'at' HH:mm:ss"));
int startFileName = inFile.LastIndexOf("\\") + 1;
string shortFileName = inFile.Substring(startFileName, inFile.LastIndexOf(".") - startFileName) + ext;
// Change the file's extension to ".enc"
string outFile = EncrFolder + inFile.Substring(startFileName, inFile.LastIndexOf(".") - startFileName) + "C" + ext;
// make sure directory exist
try {
Directory.CreateDirectory(EncrFolder);
}
catch (Exception ex)
{
MessageBox.Show("Cannot create directory .\\Encrypt\r\n" + ex.Message);
return;
}
string labelText = "Encrypting file \"" + shortFileName + "\"";
backgroundWorker1.ReportProgress(0, labelText);
// Create instance of Rijndael for
// symetric encryption of the data.
RijndaelManaged rjndl = new RijndaelManaged();
rjndl.KeySize = 256;
rjndl.BlockSize = 256;
rjndl.Mode = CipherMode.CBC;
ICryptoTransform transform = rjndl.CreateEncryptor();
// Use RSACryptoServiceProvider to
// enrypt the Rijndael key.
// rsa is previously instantiated:
// rsa = new RSACryptoServiceProvider(cspp);
byte[] keyEncrypted = rsa.Encrypt(rjndl.Key, false);
// Create byte arrays to contain
// the length values of the key and IV.
byte[] LenK = new byte[4];
byte[] LenIV = new byte[4];
int lKey = keyEncrypted.Length;
LenK = BitConverter.GetBytes(lKey);
int lIV = rjndl.IV.Length;
LenIV = BitConverter.GetBytes(lIV);
// prepare 32B dummyHash
byte[] dummyHash = new byte[32];
byte[] pad = BitConverter.GetBytes(9);
// Write the following to the FileStream
// for the encrypted file (outFs):
// - length of the key
// - length of the IV
// - ecrypted key
// - the IV
// - dummyHash to check integrity
// - the encrypted cipher content
// --- rewrite dummyHash with true hash of encrypted data
try {
using (FileStream outFs = new FileStream(outFile, FileMode.Create, FileAccess.ReadWrite, FileShare.ReadWrite, 8388608))
{
outFs.Write(LenK, 0, 4);
outFs.Write(LenIV, 0, 4);
outFs.Write(keyEncrypted, 0, lKey);
outFs.Write(rjndl.IV, 0, lIV);
// write dummyHash
outFs.Write(dummyHash, 0, dummyHash.Length);
// Now write the cipher text using
// a CryptoStream for encrypting.
using (CryptoStream outStreamEncrypted = new NotClosingCryptoStream(outFs, transform, CryptoStreamMode.Write))
{
// By encrypting a chunk at
// a time, you can save memory
// and accommodate large files.
int count = 0;
long offset = 0;
// blockSizeBytes can be any arbitrary size.
int blockSizeBytes = rjndl.BlockSize / 8;
byte[] data = new byte[blockSizeBytes];
int bytesRead = 0;
using (FileStream inFs = new FileStream(inFile, FileMode.Open, FileAccess.Read, FileShare.Read, 8388608))
{
double fileLength = inFs.Length;
double blocks = fileLength / blockSizeBytes;
int step = (int)Math.Ceiling(blocks) / 128;
if (step < 1)
{
step = 1;
}
int iteration = 1;
do
{
count = inFs.Read(data, 0, blockSizeBytes);
offset += count;
outStreamEncrypted.Write(data, 0, count);
bytesRead += blockSizeBytes;
if (iteration++ % step == 0)
{
backgroundWorker1.ReportProgress(1); //increment progressBar and NOT change label1
}
}while (count > 0);
backgroundWorker1.ReportProgress(100); //set 100% full progress bar due to very small files
Logger("Enc: Original file length = " + fileLength); //dlzka cisteho suboru
inFs.Close();
} // FileStream inFs
} // CryptoStream outStreamEncrypted
labelText = "Computing HMAC hash";
backgroundWorker1.ReportProgress(0, labelText);
// generate initialization key for HMACSHA256 provider
byte[] hashKey = new byte[lIV + 4];
rjndl.IV.CopyTo(hashKey, 0);
pad.CopyTo(hashKey, (hashKey.Length - 4));
// make and reWrite hash
using (HMACSHA256 hmac = new HMACSHA256(hashKey))
{
// set position in stream
long dataIndex = LenK.Length + LenIV.Length + lKey + lIV + dummyHash.Length;
outFs.Seek(dataIndex, SeekOrigin.Begin);
// generate hash
dummyHash = hmac.ComputeHash(outFs);
Logger("Enc: hash = " + BitConverter.ToString(dummyHash));
// write hash
dataIndex -= dummyHash.Length;
outFs.Seek(dataIndex, SeekOrigin.Begin);
outFs.Write(dummyHash, 0, dummyHash.Length);
//erase hash from memory
for (int i = 0; i < 32; i += 4)
{
pad.CopyTo(dummyHash, i);
}
}//HMACSHA256
Logger("Enc: Encrypted file length = " + outFs.Length);
labelText = "Encryption was succesful";
backgroundWorker1.ReportProgress(0, labelText);
outFs.Close();
Logger("Enc: Encryption was succesful");
finish = DateTime.Now;
TimeSpan duration = finish.Subtract(start);
Logger("Enc: Finished on " + finish.ToString("dd.MM.yyyy 'at' HH:mm:ss"));
Logger("File \"" + inFile + "\"\r\n encrypted in " +
duration.Days + " days, " +
duration.Hours + ":" +
duration.Minutes + ":" + duration.Seconds +
"." + duration.Milliseconds +
"\r\n=================================================="
);
}//outFs
}
catch (Exception exc)
{
backgroundWorker1.ReportProgress(-1);
backgroundWorker1.ReportProgress(0, "Error occured in encrypt process");
MessageBox.Show("Error occured in encrypt process\r\n" + exc.GetType() + "\r\n" + exc.Message);
}
}
