Digest auth - Freeradius & squid

Hi all. I set up a squid installation which asks for credentials to a freeradius server (with MySql DB), using squid_radius_auth. Everything works with cleartext passwords, having two entries like the following on radcheck table: id username attribute op value 1 user Cleartext-Password := password 2 user Expiration := June 30 2015 14:7:8 I'm trying to understand how can I use digest authentication: is it possible? What should I change in freeradius configuration? How should I modify user entry in radcheck table? Thanks in advance. Regards. -- GP