'Return a list of L{FilePath} instances for I{authorized_keys} files
which might contain information about authorized keys for the given
credentials.
On OpenSSH servers, the default location of the file containing the
list of authorized public keys is
U{$HOME/.ssh/authorized_keys<http://www.openbsd.org/cgi-bin/man.cgi?query=sshd_config>}.
I{$HOME/.ssh/authorized_keys2} is also returned, though it has been
U{deprecated by OpenSSH since
2001<http://marc.info/?m=100508718416162>}.
@return: A list of L{FilePath} instances to files with the authorized keys.'

def getAuthorizedKeysFiles(self, credentials):

    pwent = self._userdb.getpwnam(credentials.username)
    root = FilePath(pwent.pw_dir).child('.ssh')
    files = ['authorized_keys', 'authorized_keys2']
    return [root.child(f) for f in files]
