[Help-gnunet] Questions about GNUnet

[Philipp]

Hello everyone,
I am currently working on my master's thesis at the University of Ulm.  
As a part of my thesis, I performed a literature survey on some  
systems that offer anonymity properties in P2P environments, among  
them GNUnet.

I have a few questions regarding GNUnet. I hope it is fine to post  
them here on the mailing list. Unfortunately, when visiting the FAQ  
website https://gnunet.org/faq-page I just get an emtpy page, so I  
couldn't figure out whether there are already answers posted to some  
of the questions I have.

I would be very grateful for help on some of these topics.

1) In [1], it is mentioned that nodes observe the behavior of  
neighboring nodes. It also states that a node might pass files (or  
possbily blocks of a file) to other nodes depending on how trustworthy  
they seem. Are these trust values derived based on the scheme  
described in [2]?

2) As far as I understood, files that I want to publish are always  
placed on my local node and not actively distributed into the network.  
I can, however, decide whether I want to generate a copy and place it  
in my local store in encrypted form or whether I just want to create  
the index and blocks are encrypted "on-the-fly" when requested. In  
[3], the term "content migration" is used. Are blocks actively pushed  
to other nodes even without requests on them?

3) https://gnunet.org/file-sharing-concepts mentions a replication  
level for blocks. What exactly is the purpose for this and how does it  
affect replication?

4) In the GAP approach described in [4], a peer, say A, can decide to  
skip the source rewriting step. On the return path, the successor of A  
needs to communicate directly with the predecessor of A. However,  
GNUnet uses encrypted links. Does this imply that these nodes need to  
perform a session key exchange before being able to send the result  
along the return path?

5) Taking a look at [3] or [4], the network is described as a rather  
unstructured P2P network. I know also about the DHT based R5N [5]  
which is a structured approach. How does these two play together in  
terms of network management? Are there separate routing tables and  
maintenance protocols?

6) I know R5N is currently used for non-anonymous file sharing. There  
is not really sender anonymity due to the hop counter that is used to  
determine when to switch from random to deterministic routing.  
Furthermore, packets are not intentionally delayed to impede traffic  
analysis. However, would it be possible to apply similar mechanisms  
just like in GAP and, e.g., replace the hop counter or use  
probabilistic behavir to achieve sender anonymity in R5N?

7) Does GNUnet use erasure codes to tolerate the loss of some of the  
blocks of a file? Or is a file unretrievable if a block is lost?

8) Are there any performance measurements in a scientific publication  
about GAP or GNUnets anonymous file sharing in general?

[1] Grothoff, Christian, et al. "The gnet whitepaper." Purdue  
University (2002).
[2] Grothoff, Christian. "Resource allocation in peer-to-peer  
networks: An excess-based economic model." Wirtschaftsinformatik 45.3  
(2003): 285-292.
[3] Bennett, Krista, et al. "Gnunet-a truly anonymous networking  
infrastructure." In: Proc. Privacy Enhancing Technologies Workshop  
(PET. 2002.
[4] Bennett, Krista, and Christian Grothoff. "GAP–practical anonymous  
networking." International Workshop on Privacy Enhancing Technologies.  
Springer Berlin Heidelberg, 2003.
[5] Evans, Nathan S., and Christian Grothoff. "R5n: Randomized  
recursive routing for restricted-route networks." Network and System  
Security (NSS), 2011 5th International Conference on. IEEE, 2011.

Best regards,
Philipp