/// <summary>
/// Get a key for an existing database. First, the key file is located, either because its location
/// and filename are the same as the database path (with the exception of the extension), or the user
/// is asked. Then, the key file is decrypted using a private key.
/// </summary>
/// <param name="strPath">Full filename of the database file.</param>
/// <returns>A byte array with the key, or null if an error occurs. If an error occurs, user is
/// notified of the error.</returns>
byte[] GetExistingKey(IOConnectionInfo ioc)
{
Stream stream = null;
try
{
string newpath = UrlUtil.StripExtension(ioc.Path) + "." + CertProtKeyFileExtension;
IOConnectionInfo keyIoc = ioc.CloneDeep();
keyIoc.Path = newpath;
stream = IOConnection.OpenRead(keyIoc);
}
catch (Exception e)
{
// strPath may be a URL (even if IsLocalFile returns true?),
// whatever the reason, fall through and the user can pick a
// local file as the key file
}
if (stream == null || !stream.CanRead)
{
// fall back on opening a local file
// FUTURE ENHANCEMENT: allow user to enter a URL and name/pwd as well
OpenFileDialog ofd = UIUtil.CreateOpenFileDialog("KeePassX509Provider", UIUtil.CreateFileTypeFilter(CertProtKeyFileExtension, "x05KeyFile", true), 1, CertProtKeyFileExtension, false /* multi-select */, true);
if (ofd.ShowDialog() != DialogResult.OK)
{
return(null);
}
stream = IOConnection.OpenRead(IOConnectionInfo.FromPath(ofd.FileName));
}
try
{
BinaryReader reader = new BinaryReader(stream);
byte[] p7m = reader.ReadBytes(MAX_KEY_FILE_LENGTH);
// URL streams don't support seeking, and so Position doesn't work
//bool tooBig = stream.Position >= MAX_KEY_FILE_LENGTH;
bool tooBig = p7m.Length >= MAX_KEY_FILE_LENGTH;
reader.Close();
if (tooBig)
{
MessageBox.Show("Kes File ist to big");
return(null);
}
Certmanager cert_mgr = new Certmanager();
return(cert_mgr.DecryptMsg(p7m));
}
catch (SystemException ex) // covers IOException and CryptographicException
{
MessageBox.Show("Error at encryption or IO error!\nIf you used a smart card for encryption, please provide/plugin fist!");
return(null);
}
}