Frank, Yes the identity digest is the sha1 hash/digest of the OR public
key. This router fingerprint is this hash base16 encrypted. In the case of
finding responsible hidden service directories, the Tor client just sorts
all routers with the HSDir by the raw binary encoding of the public key
digest
A Tor client generates the desc_id for the v2 hidden service it would like
to query. It did selects the 3 HSDIR from the router list which are found
directly after the position of the desc_id when the routers are sorted by
their identity digest (hash of their onion public key). I took me quite a
wh
