class digest_auth_handler :?enable_auth_in_advance:bool -> #key_handler ->auth_handler
This handler is compatible with RFC 2069 and RFC 2617. In particular, the following protocol options are available:
Authentication-Info header is completely
   ignoredenable_auth_in_advance: If set to true, authentication can be
 done in advance, i.e. before the server requests authentication.
 This reduces the number of messages exchanged with the server, but
 may be an additional security risk.