private static void DecryptFile(string filePath, int parametersLength, byte[] macBackup, byte[] encryptionKey, BackgroundWorker bgwDecryption)
{
try
{
string decryptedFilePath = Regex.Replace(filePath, Constants.EncryptedExtension, string.Empty);
int headersLength = Constants.SaltLength + parametersLength;
using (var plaintext = new FileStream(decryptedFilePath, FileMode.Create, FileAccess.ReadWrite, FileShare.Read, Constants.FileBufferSize, FileOptions.SequentialScan))
using (var ciphertext = new FileStream(filePath, FileMode.Open, FileAccess.ReadWrite, FileShare.Read, Constants.FileBufferSize, FileOptions.SequentialScan))
{
// Skip the header bytes
ciphertext.Seek(headersLength, SeekOrigin.Begin);
byte[] fileBytes = FileHandling.GetBufferSize(ciphertext.Length);
// Generate a counter starting at 0
byte[] counter = Generate.Counter();
int bytesRead;
MemoryEncryption.DecryptByteArray(ref encryptionKey);
while ((bytesRead = ciphertext.Read(fileBytes, 0, fileBytes.Length)) > 0)
{
byte[] decryptedBytes = StreamEncryption.DecryptXChaCha20(fileBytes, counter, encryptionKey);
plaintext.Write(decryptedBytes, 0, bytesRead);
counter = Sodium.Utilities.Increment(counter);
// Report progress if decrypting a single file
ReportProgress.ReportEncryptionProgress(plaintext.Position, ciphertext.Length, bgwDecryption);
}
Utilities.ZeroArray(encryptionKey);
}
CompleteDecryption(filePath, decryptedFilePath);
}
catch (Exception ex) when(ExceptionFilters.FileEncryptionExceptions(ex))
{
Logging.LogException(ex.ToString(), Logging.Severity.High);
DisplayMessage.ErrorResultsText(filePath, ex.GetType().Name, "Failed to backup the MAC. This data is required for decryption.");
Utilities.ZeroArray(encryptionKey);
RestoreMAC(filePath, macBackup);
}
}
private static void EncryptFile(string filePath, string encryptedFilePath, byte[] salt, byte[] encryptionKey, byte[] macKey, BackgroundWorker bgwEncryption)
{
try
{
using (var ciphertext = new FileStream(encryptedFilePath, FileMode.Create, FileAccess.ReadWrite, FileShare.Read, Constants.FileBufferSize, FileOptions.SequentialScan))
using (var plaintext = new FileStream(filePath, FileMode.Open, FileAccess.ReadWrite, FileShare.Read, Constants.FileBufferSize, FileOptions.SequentialScan))
{
WriteFileHeaders.WriteHeaders(ciphertext, salt);
// Store headers length to correct percentage calculation
long headersLength = ciphertext.Position;
byte[] fileBytes = FileHandling.GetBufferSize(plaintext.Length);
// Generate a counter starting at 0
byte[] counter = Generate.Counter();
int bytesRead;
MemoryEncryption.DecryptByteArray(ref encryptionKey);
while ((bytesRead = plaintext.Read(fileBytes, 0, fileBytes.Length)) > 0)
{
byte[] encryptedBytes = StreamEncryption.EncryptXChaCha20(fileBytes, counter, encryptionKey);
ciphertext.Write(encryptedBytes, 0, bytesRead);
counter = Sodium.Utilities.Increment(counter);
// Report progress if encrypting a single file
ReportProgress.ReportEncryptionProgress(ciphertext.Position, plaintext.Length + headersLength, bgwEncryption);
}
}
Utilities.ZeroArray(encryptionKey);
CompleteEncryption(filePath, encryptedFilePath, macKey);
}
catch (Exception ex) when(ExceptionFilters.FileEncryptionExceptions(ex))
{
Logging.LogException(ex.ToString(), Logging.Severity.High);
DisplayMessage.ErrorResultsText(filePath, ex.GetType().Name, "Unable to encrypt the file.");
FileHandling.DeleteFile(encryptedFilePath);
Utilities.ZeroArray(encryptionKey);
Utilities.ZeroArray(macKey);
}
}