public bool Decrypt(string FilePath, byte[] Key, int Rounds, Mode Mode, EncryptionMode EncrMode)
{
var fm = new FileManagement();
SerpentAlgorithm sa;
switch (Mode)
{
case Mode.Standard:
sa = new SerpentStandardMode();
break;
case Mode.BitSlice:
sa = new SerpentBitSliceMode();
break;
default:
MessageBox.Show("Selected algorithm type is not implemented. ", "Error", MessageBoxButton.OK, MessageBoxImage.Error);
return(false);
}
var position = 0;
var destFilePath = string.Empty;
var fi = new FileInfo(FilePath);
const int fragmentSize = 1024 * 1024; // 1 MB (musi dać się wyciągnąć pierwiastek czwartego stopnia)
Encoding enc = new UTF8Encoding();
sa.Rounds = Rounds;
sa.BlockSize = BlockSize;
var tempFilePath = FilePath + ".temp";
var iv = fm.GetFileFragment(FilePath, 0, BlockSize, out var errorCodeIv);
var plainControlSum = fm.GetFileFragment(FilePath, BlockSize, BlockSize, out var errorCode);
var roundBytesFromPtControlSum = Array.Empty <byte>();
var previousBlock = Array.Empty <byte>();
if (errorCodeIv == ErrorCode.GetFileFailed || errorCode == ErrorCode.GetFileFailed)
{
MessageBox.Show("File couldn't be loaded.", "Error", MessageBoxButton.OK, MessageBoxImage.Error);
return(false);
}
var listRoundsBytesFromPtControlSum = new List <byte>();
for (var i = 0; i < BlockSize; i++)
{
if (plainControlSum[i] != 3)
{
listRoundsBytesFromPtControlSum.Add(plainControlSum[i]);
}
else
{
roundBytesFromPtControlSum = listRoundsBytesFromPtControlSum.ToArray();
break;
}
}
var areRoundsFromPtControlSumParsable = int.TryParse(enc.GetString(roundBytesFromPtControlSum), out var readRoundsFromPtControlSum);
if (!areRoundsFromPtControlSumParsable || readRoundsFromPtControlSum > 64)
{
MessageBox.Show("File isn't encrypted or it was encrypted with different algorithm.", "Error", MessageBoxButton.OK, MessageBoxImage.Error);
return(false);
}
if (readRoundsFromPtControlSum != Rounds)
{
if (Mode != Mode.Standard)
{
var result = MessageBox.Show(string.Format("File was encrypted with different number of rounds ({0}) of Serpent algorithm than the one specified ({1}) and in algorithm type different than `Standard` it is impossible to decrypt by using this number of rounds. Do you want to change alogorithm type to 'Standard' and number of rounds to {0}? (WARNING: Decryption may take a long time for big files). ", readRoundsFromPtControlSum, Rounds), "Warning", MessageBoxButton.YesNo, MessageBoxImage.Warning);
return(result == MessageBoxResult.Yes && Decrypt(FilePath, Key, readRoundsFromPtControlSum, Mode.Standard, EncrMode));
}
else
{
var result = MessageBox.Show(string.Format("It looks like the file was encrypted with different number of rounds ({0}) of Serpent algorithm than the one specified ({1}) or file is not encrypted at all. Do you want to change the number of rounds to {0}?", readRoundsFromPtControlSum, Rounds), "Warning", MessageBoxButton.YesNo, MessageBoxImage.Question);
if (result == MessageBoxResult.Yes)
{
Rounds = readRoundsFromPtControlSum;
sa.Rounds = readRoundsFromPtControlSum;
}
}
}
var expandedKey = sa.MakeKey(Key);
fm.ShiftBytesFromFile(FilePath, tempFilePath, BlockSize * 2, out errorCode); // usuń z pliku dwa bloki - sumę kontrolną i initalization vector
if (errorCode == ErrorCode.ShiftFileFailed)
{
MessageBox.Show("File couldn't be modified.", "Error", MessageBoxButton.OK, MessageBoxImage.Error);
return(false);
}
do
{
var InputFileFragment = fm.GetFileFragment(tempFilePath, position, fragmentSize, out errorCode).ToList();
if (errorCode == ErrorCode.GetFileFailed)
{
MessageBox.Show("File couldn't be loaded'.", "Error", MessageBoxButton.OK, MessageBoxImage.Error);
return(false);
}
var OutputFileFragment = new List <byte>();
// DESZYFROWANIE BLOKU
for (var i = 0; i < InputFileFragment.Count; i += BlockSize)
{
switch (EncrMode)
{
case EncryptionMode.ECB:
OutputFileFragment.AddRange(sa.BlockDecrypt(InputFileFragment.GetRange(i, BlockSize).ToArray(), 0, expandedKey));
break;
case EncryptionMode.CBC:
{
if (position == 0 && i == 0)
{
previousBlock = iv;
}
var cipherText = InputFileFragment.GetRange(i, BlockSize).ToArray();
var currBlock = sa.BlockDecrypt(cipherText, 0, expandedKey);
var plainText = currBlock.XOR(previousBlock);
OutputFileFragment.AddRange(plainText);
previousBlock = cipherText;
break;
}
default:
MessageBox.Show("Selected ciphering type is not implemented. ", "Error", MessageBoxButton.OK, MessageBoxImage.Error);
return(false);
}
}
// ===================
if (position == 0) // jeśli odszyfrowałem pierwszy fragment pliku, przed zapisaniem usuwam z tablicy bajty dodane przy szyfrowaniu
{
int shiftedbytes = OutputFileFragment[BlockSize * 2]; // zawartość 32 bajtu, 0 - 15 deszyfrowana suma kontrolna, 16-31 rozszerzenie i ilość rund
var decryptedControlSum = new byte[BlockSize];
var extBytes = new byte[1];
var roundBytes = new byte[1];
var i = 0;
for (; i < BlockSize; i++) // zczytaj sumę kontrolną
{
decryptedControlSum[i] = OutputFileFragment[i];
}
var listExtbytes = new List <byte>();
for (; i < BlockSize * 2; i++) // zczytaj rozszerzenie
{
if (OutputFileFragment[i] != 3)
{
listExtbytes.Add(OutputFileFragment[i]);
}
else
{
extBytes = listExtbytes.ToArray();
break;
}
}
i++;
var listRoundsBytes = new List <byte>();
for (; i < BlockSize * 2; i++) // zczytaj zaszyfrowaną ilość rund
{
if (OutputFileFragment[i] != 3)
{
listRoundsBytes.Add(OutputFileFragment[i]);
}
else
{
roundBytes = listRoundsBytes.ToArray();
break;
}
}
var outputExtension = enc.GetString(extBytes);
destFilePath = Path.ChangeExtension(FilePath, outputExtension);
var areRoundsParsable = int.TryParse(enc.GetString(roundBytes), out var readRounds);
if (!plainControlSum.SequenceEqual(decryptedControlSum) || !areRoundsParsable || shiftedbytes > 16 || readRounds != Rounds)
{
fm.DeleteTempFile(tempFilePath, out errorCode);
if (errorCode == ErrorCode.DeletingTempFileFailed)
{
MessageBox.Show("Temporary file couldn't be deleted", "Warning", MessageBoxButton.OK, MessageBoxImage.Warning);
}
MessageBox.Show("Key is invalid.", "Error", MessageBoxButton.OK, MessageBoxImage.Error);
return(false);
}
var shiftedBytesAndInfoBytes = shiftedbytes + BlockSize * 2;
for (; shiftedBytesAndInfoBytes > 0; shiftedBytesAndInfoBytes--)
{
OutputFileFragment.RemoveAt(0);
}
}
fm.SaveFileFragment(destFilePath, position, OutputFileFragment.ToArray(), out errorCode); // zapisuję kolejną część pliku do pliku docelowego
if (errorCode == ErrorCode.SaveFileFailed) // w razie błędu szyfrowanie nie powiodło się
{
MessageBox.Show("FIle couldn't be saved. ", "Error", MessageBoxButton.OK, MessageBoxImage.Error);
return(false);
}
position += fragmentSize; // ustaw pozycję kolejnego fragmentu
var encryptionProgressChangedEventData = new EncryptionProgressChangedEventArgs((int)((double)position / fi.Length * 100.0), ActionType.Decryption); // inicjalizuję dane dla event handlera (obliczony postęp, typ - szyfrowanie czy deszyfrowanie)
OnEncryptionProgressChanging(encryptionProgressChangedEventData); // wywołuję zdarzenie z utworzonymi wcześniej parametrami
}while (position <= fi.Length); // pętlę powtarzam dopóki nie skończy się plik
fm.DeleteTempFile(tempFilePath, out errorCode); // usuń plik tymczasowy
if (errorCode == ErrorCode.DeletingTempFileFailed)
{
MessageBox.Show("Temporary file couldn't be deleted.", "Ostrzeżenie", MessageBoxButton.OK, MessageBoxImage.Warning);
}
return(true);
}
public bool Encrypt(string FilePath, byte[] Key, int Rounds, Mode Mode, EncryptionMode EncrMode)
{
var fm = new FileManagement();
SerpentAlgorithm sa;
var saltBytes = new byte[BlockSize];
rng.GetNonZeroBytes(saltBytes);
var iv = new byte[BlockSize];
rng.GetBytes(iv);
switch (Mode)
{
case Mode.Standard:
sa = new SerpentStandardMode();
break;
case Mode.BitSlice:
sa = new SerpentBitSliceMode();
break;
default:
MessageBox.Show("Selected algorithm type is not implemented. ", "Error", MessageBoxButton.OK, MessageBoxImage.Error);
return(false);
}
var position = 0;
var destFilePath = Path.ChangeExtension(FilePath, ".serpent");
var fi = new FileInfo(FilePath);
var fragmentSize = 1024 * 1024; // 1 MB (musi dać się wyciągnąć pierwiastek czwartego stopnia)
var tempFilePath = FilePath + ".temp";
var tempFilePath2 = FilePath + ".temp2";
Encoding enc = new UTF8Encoding();
sa.Rounds = Rounds;
sa.BlockSize = BlockSize;
var previousBlock = Array.Empty <byte>();
var roundsBytes = enc.GetBytes(Rounds.ToString());
for (var i = 0; i < roundsBytes.Length; i++)
{
saltBytes[i] = roundsBytes[i];
if (i >= roundsBytes.Length - 1)
{
saltBytes[i + 1] = 3;
}
}
var expandedKey = sa.MakeKey(Key);
var leadingBytes = new byte[BlockSize - fi.Length % BlockSize];
rng.GetBytes(leadingBytes);
leadingBytes[0] = (byte)leadingBytes.Length;
fm.UnshiftBytesToFile(FilePath, tempFilePath, leadingBytes, out var errorCode); // po czym dodaję go do pliku tymczasowego
if (errorCode == ErrorCode.ExpandFileFailed)
{
MessageBox.Show("File couldn't be modified.", "Error", MessageBoxButton.OK, MessageBoxImage.Error);
return(false);
}
do
{
if (position == 0) // dodaj do pliku informację o rozszerzeniu, ilości rund i sumę kontrolną
{
var infoBytes = new List <byte>();
infoBytes.AddRange(saltBytes);
var extension = Path.GetExtension(FilePath);
extension = extension.Replace(".", "");
infoBytes.AddRange(enc.GetBytes(extension));
infoBytes.Add(3); // EOT byte
infoBytes.AddRange(enc.GetBytes(Rounds.ToString()));
infoBytes.Add(3);
if (BlockSize < infoBytes.Count - saltBytes.Length)
{
MessageBox.Show("FIle extension is too long.", "Error", MessageBoxButton.OK, MessageBoxImage.Error);
return(false);
}
var rndBytes = new byte[BlockSize - (infoBytes.Count - saltBytes.Length)];
rng.GetNonZeroBytes(rndBytes);
infoBytes.AddRange(rndBytes);
fm.UnshiftBytesToFile(tempFilePath, tempFilePath2, infoBytes.ToArray(), out errorCode);
if (errorCode == ErrorCode.ExpandFileFailed)
{
MessageBox.Show("File couldn't be modified.", "Error", MessageBoxButton.OK, MessageBoxImage.Error);
return(false);
}
fm.DeleteTempFile(tempFilePath, out errorCode);
if (errorCode == ErrorCode.DeletingTempFileFailed) // w razie błędu szyfrowanie nie powiodło się
{
MessageBox.Show("Temporary file couldn't be deleted.", "Warning", MessageBoxButton.OK, MessageBoxImage.Warning);
return(false);
}
File.Move(tempFilePath2, tempFilePath);
}
var InputFileFragment = fm.GetFileFragment(tempFilePath, position, fragmentSize, out errorCode).ToList();
if (errorCode == ErrorCode.GetFileFailed)
{
MessageBox.Show("File couldn't be loaded.", "Error", MessageBoxButton.OK, MessageBoxImage.Error);
return(false);
}
var OutputFileFragment = new List <byte>();
// SZYFROWANIE BLOKU
for (var i = 0; i < InputFileFragment.Count; i += BlockSize)
{
if (EncrMode == EncryptionMode.ECB)
{
OutputFileFragment.AddRange(sa.BlockEncrypt(InputFileFragment.GetRange(i, BlockSize).ToArray(), 0, expandedKey));
}
else if (EncrMode == EncryptionMode.CBC)
{
if (position == 0 && i == 0) // inicjalizuję iv tylko raz
{
previousBlock = iv;
}
var plainText = InputFileFragment.GetRange(i, BlockSize).ToArray();
var currBlock = plainText.XOR(previousBlock); // do plaintextu xorujemy poprzedni zaszyfrowany blok
var cipherText = sa.BlockEncrypt(currBlock, 0, expandedKey);
OutputFileFragment.AddRange(cipherText);
previousBlock = cipherText;
}
else
{
MessageBox.Show("Selected ciphering type is not implemented. ", "Error", MessageBoxButton.OK, MessageBoxImage.Error);
return(false);
}
}
// =================
fm.SaveFileFragment(destFilePath, position, OutputFileFragment.ToArray(), out errorCode); // zapisuję kolejną część pliku do pliku docelowego
if (errorCode == ErrorCode.SaveFileFailed) // w razie błędu szyfrowanie nie powiodło się
{
MessageBox.Show("File couldn't be saved. ", "Error", MessageBoxButton.OK, MessageBoxImage.Error);
return(false);
}
position += fragmentSize; // ustaw pozycję kolejnego fragmentu
var encryptionProgressChangedEventData = new EncryptionProgressChangedEventArgs(((int)((double)position / fi.Length * 100.0)), ActionType.Encryption); // inicjalizuję dane dla event handlera (obliczony postęp, typ - szyfrowanie czy deszyfrowanie)
OnEncryptionProgressChanging(encryptionProgressChangedEventData); // wywołuję zdarzenie z utworzonymi wcześniej parametrami
}while (position <= fi.Length); // pętlę powtarzam dopóki nie skończy się plik
fm.DeleteTempFile(tempFilePath, out errorCode); // usuń plik tymczasowy
if (errorCode == ErrorCode.DeletingTempFileFailed) // w razie błędu szyfrowanie nie powiodło się
{
MessageBox.Show("Temporary file couldn't be deleted.", "Error", MessageBoxButton.OK, MessageBoxImage.Error);
return(false);
}
var ivAndSalt = new byte[iv.Length + saltBytes.Length];
iv.CopyTo(ivAndSalt, 0);
saltBytes.CopyTo(ivAndSalt, iv.Length);
fm.UnshiftBytesToFile(destFilePath, tempFilePath, ivAndSalt, out errorCode); // suma kontrolna
if (errorCode == ErrorCode.ExpandFileFailed)
{
MessageBox.Show("File couldn't be modified.", "Error", MessageBoxButton.OK, MessageBoxImage.Error);
return(false);
}
fm.DeleteTempFile(destFilePath, out errorCode); // usuń plik tymczasowy
if (errorCode == ErrorCode.DeletingTempFileFailed) // w razie błędu szyfrowanie nie powiodło się
{
MessageBox.Show("Temporary file couldn't be deleted.", "Ostrzeżenie", MessageBoxButton.OK, MessageBoxImage.Warning);
}
File.Move(tempFilePath, destFilePath);
return(true);
}
