private void StartDecrypting(Object sender, RoutedEventArgs e)
{
if (filename == null)
{
MessageBox.Show("No file chosen", "Cryptographer", MessageBoxButton.OK, MessageBoxImage.Error);
return;
}
string selectedUserEmail;
try
{
selectedUserEmail = usersBox.SelectedItem.ToString().Split(' ')[1];
}
catch (Exception) { return; }
if (selectedUserEmail != UsersControler.currentUser.email)
{
var x = usersBox.SelectedItem.ToString();
var y = UsersControler.currentUser.email;
return;
}
string encryptedFileContent = File.ReadAllText(filepath);
string XMLStringMetadata = encryptedFileContent.Split(new[] { "</EncryptedFileHeader>" }, StringSplitOptions.None)[0] + "</EncryptedFileHeader>";
string encyptedData = encryptedFileContent.Split(new[] { "</EncryptedFileHeader>" }, StringSplitOptions.None)[1];
string sessionKey = null;
XmlDocument doc = new XmlDocument();
doc.LoadXml(XMLStringMetadata);
byte[] IV = Convert.FromBase64String(doc.SelectSingleNode("EncryptedFileHeader/IV").InnerText);
CipherMode encryptionMode = 0;
string cipherMode = doc.SelectSingleNode("EncryptedFileHeader/CipherMode").InnerText;
if (cipherMode == "ECB")
{
encryptionMode = CipherMode.ECB;
}
if (cipherMode == "CBC")
{
encryptionMode = CipherMode.CBC;
}
if (cipherMode == "CFB")
{
encryptionMode = CipherMode.CFB;
}
XmlNodeList approvedUserNodes = doc.SelectNodes("/EncryptedFileHeader/ApprovedUsers");
foreach (XmlNode node in approvedUserNodes)
{
if (UsersControler.currentUser.email == node.SelectSingleNode("User/Email").InnerText)
{
string encryptedSessionKey = node.SelectSingleNode("User/SessionKey").InnerText;
sessionKey = Decrypt(encryptedSessionKey, UsersControler.currentUser.rsaPublicPrivateKey);
break;
}
}
if (sessionKey == null)
{
MessageBox.Show("No user fitting to detailed in XML metadata");
return;
}
SaveFileDialog sf = new SaveFileDialog();
sf.FileName = filename.Remove(filename.Length - 4);
bool?safeDialogResult = sf.ShowDialog();
if (safeDialogResult == true)
{
File.WriteAllText(Path.GetFullPath(sf.FileName), AESCryptography.DecryptStringFromBytes(Convert.FromBase64String(encyptedData), Convert.FromBase64String(sessionKey), IV, encryptionMode));
}
}