try to address #5660:

2 files changed, 26 insertions, 16 deletions

diff --git a/doc/handbook/chapters/keyconcepts.texi b/doc/handbook/chapters/keyconcepts.texi
index 4b49a7ffb..4900ed328 100644
--- a/doc/handbook/chapters/keyconcepts.texi
+++ b/doc/handbook/chapters/keyconcepts.texi
@@ -15,7 +15,7 @@ The second part describes concepts specific to anonymous file-sharing.
 * Accounting to Encourage Resource Sharing::
 * Confidentiality::
 * Anonymity::
-* Deniability::                       
+* Deniability::
 * Peer Identities::
 * Zones in the GNU Name System (GNS Zones)::
 * Egos::
@@ -165,16 +165,20 @@ and Bart Preneel. Towards measuring anonymity.
 (@uref{https://git.gnunet.org/bibliography.git/plain/docs/article-89.pdf, https://git.gnunet.org/bibliography.git/plain/docs/article-89.pdf}))
 that can help quantify the level of anonymity that a given mechanism
 provides, there is no such thing as "complete anonymity".
+
 GNUnet's file-sharing implementation allows users to select for each
 operation (publish, search, download) the desired level of anonymity.
-The metric used is the amount of cover traffic available to hide the
-request.
-While this metric is not as good as, for example, the theoretical metric
-given in scientific metrics,
-it is probably the best metric available to a peer with a purely local
-view of the world that does not rely on unreliable external information.
-The default anonymity level is @code{1}, which uses anonymous routing but
-imposes no minimal requirements on cover traffic. It is possible
+The metric used is based on the amount of cover traffic needed to hide
+the request.
+
+While there is no clear way to relate the amount of available cover
+traffic to traditional scientific metrics such as the anonymity set or
+information leakage, it is probably the best metric available to a
+peer with a purely local view of the world, in that it does not rely
+on unreliable external information or a particular adversary model.
+
+The default anonymity level is @code{1}, which uses anonymous routing
+but imposes no minimal requirements on cover traffic. It is possible
 to forego anonymity when this is not required. The anonymity level of
 @code{0} allows GNUnet to use more efficient, non-anonymous routing.
 
@@ -192,7 +196,7 @@ In particular, we assume that the adversary can see all the traffic on
 the Internet. And while we assume that the adversary
 can not break our encryption, we assume that the adversary has many
 participating nodes in the network and that it can thus see many of the
-node-to-node interactions since it controls some of the nodes. 
+node-to-node interactions since it controls some of the nodes.
 
 The system tries to achieve anonymity based on the idea that users can be
 anonymous if they can hide their actions in the traffic created by other
@@ -235,7 +239,7 @@ Even if the user that downloads data and the server that provides data are
 anonymous, the intermediaries may still be targets. In particular, if the
 intermediaries can find out which queries or which content they are
 processing, a strong adversary could try to force them to censor
-certain materials. 
+certain materials.
 
 With the file-encoding used by GNUnet's anonymous file-sharing, this
 problem does not arise.
diff --git a/doc/handbook/chapters/user.texi b/doc/handbook/chapters/user.texi
index 37c5849ab..55518bc34 100644
--- a/doc/handbook/chapters/user.texi
+++ b/doc/handbook/chapters/user.texi
@@ -1054,8 +1054,17 @@ anonymity level of "1" means that anonymous routing is desired, but no
 particular amount of cover traffic is necessary. A powerful adversary
 might thus still be able to deduce the origin of the traffic using
 traffic analysis. Specifying higher anonymity levels increases the
-amount of cover traffic required. While this offers better privacy,
-it can also significantly hurt performance.
+amount of cover traffic required.
+
+The specific numeric value (for anonymity levels above 1) is simple:
+Given an anonymity level L (above 1), each request FS makes on your
+behalf must be hidden in L-1 equivalent requests of cover traffic
+(traffic your peer routes for others) in the same time-period.  The
+time-period is twice the average delay by which GNUnet artificially
+delays traffic.
+
+While higher anonymity levels may offer better privacy, they can also
+significantly hurt performance.
 
 @node Content Priority
 @subsubsection Content Priority
@@ -2324,6 +2333,3 @@ service offered by that peer, you can create an IP tunnel to
 that peer by specifying the peer's identity, service name and
 protocol (--tcp or --udp) and you will again receive an IP address
 that will terminate at the respective peer's service.
-
-
-