/// <summary>
/// Decrypts the selected file using the given password
/// </summary>
/// <param name="inputFile">Encrypted File</param>
/// <param name="password">Password to decrypt the file</param>
/// <param name="percentComplete">Percent of completion</param>
/// <returns>If the decryption was successful</returns>
internal bool Decrypt(string inputFile, string password, ref decimal percentComplete)
{
byte[] passwordBytes = Encoding.UTF8.GetBytes(password);
FileStream fsCrypt = new FileStream(inputFile, FileMode.Open);
fsCrypt = DecryptModeHandler(fsCrypt, out byte[] hash, out byte[] salt, out byte[] faesCBCMode, out byte[] faesMetaData, out var cipher);
const int keySize = 256;
const int blockSize = 128;
Rfc2898DeriveBytes key = new Rfc2898DeriveBytes(passwordBytes, salt, 50000);
RijndaelManaged AES = new RijndaelManaged
{
KeySize = keySize,
BlockSize = blockSize,
Key = key.GetBytes(keySize / 8),
IV = key.GetBytes(blockSize / 8),
Padding = PaddingMode.PKCS7,
Mode = cipher
};
try
{
CryptoStream cs = new CryptoStream(fsCrypt, AES.CreateDecryptor(), CryptoStreamMode.Read);
string outputName = Path.ChangeExtension(inputFile, FileAES_Utilities.ExtentionUFAES);
try
{
FileStream fsOut = new FileStream(outputName, FileMode.Create);
File.SetAttributes(outputName, FileAttributes.Hidden);
byte[] buffer = new byte[FileAES_Utilities.GetCryptoStreamBuffer()];
long expectedComplete = fsCrypt.Length + hash.Length + salt.Length + faesCBCMode.Length + faesMetaData.Length + AES.KeySize + AES.BlockSize;
try
{
int read;
Logging.Log("Beginning writing decrypted data...", Severity.DEBUG);
while ((read = cs.Read(buffer, 0, buffer.Length)) > 0)
{
try
{
percentComplete = Math.Ceiling((decimal)((Convert.ToDouble(fsOut.Length) / Convert.ToDouble(expectedComplete)) * 100));
if (percentComplete > 100)
{
percentComplete = 100;
}
}
catch
{
Logging.Log("Percentage completion calculation failed!", Severity.WARN);
}
fsOut.Write(buffer, 0, read);
}
Logging.Log("Finished writing decrypted data.", Severity.DEBUG);
}
catch
{
fsOut.Close();
}
cs.Close();
fsOut.Close();
fsCrypt.Close();
if (Checksums.ConvertHashToString(hash) != Checksums.ConvertHashToString(Checksums.GetSHA1(outputName)))
{
Logging.Log("Invalid Checksum detected! Assuming password is incorrect.", Severity.DEBUG);
FileAES_IntUtilities.SafeDeleteFile(outputName);
return(false);
}
Logging.Log("Valid Checksum detected!", Severity.DEBUG);
return(true);
}
catch
{
cs.Close();
fsCrypt.Close();
return(false);
}
}
catch (CryptographicException)
{
fsCrypt.Close();
return(false);
}
}
