davfs2 allows to store user's passwords on $.davfs2/secrets in plain text in order to then allow the user to mount the webdav without prompting for password.
Is it possible to store the password pre-encrypted? The idea would be that the user herself type the password in an interactive script that (knowing the encrypting algorithm) convert it in encrypted form and save it on $.davfs2/secrets.
In this way even root would not have access (brute-force apart) to the user password.