RADIUS attribute from rfc5090
This attribute holds the algorithm parameter that influences
the HTTP Digest calculation. It MUST only be used in Access-
Request, Access-Challenge and Accounting-Request packets. If
this attribute is missing, MD5 is assumed.
111 for Digest-Algorithm
In Access-Requests, the RADIUS client takes the value of the
algorithm directive (as described in)
from the HTTP-style request it wants to authenticate. In
Access-Challenge packets, the RADIUS server SHOULD put the
desired algorithm into this attribute.