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
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