Re: [Pearg] Research Group Last Call for "A Survey of Worldwide Censorship Techniques"

[Chelsea Komlo <[e-mail]>]

Hi Chris,

I have a couple meta points and a few specific points.

Overall, my strongest recommendation is threefold. First, I recommend
improving the document organization to clearly differentiate between a
specific censorship technique and corresponding methods to circumvent that
technique. Second, I suggest strengthening the review of current
circumvention techniques and their effectiveness to give an improved view
of the landscape and to prevent re-inventing the wheel, as the intended
audience is protocol designers. Third, I recommend differentiating between
the capabilities of mature censors like China, and weaker censors such as
those with only off-the-shelf tools.

Here is my discussion of these points in more detail.

=== Meta Points ===
- While I understand this draft to be purely informational, understanding
censorship today is incomplete without understanding existing censorship
circumvention techniques, and how effective these techniques are.
Critically, some of the most effective and safe censorship techniques are
"hanging by a thread" in terms of how much longer they will be available
(such as domain fronting), so understanding these weak areas is important
to understanding the sustainability of the current circumvention landscape.
I suggest adding at minimum a discussion of "Where are we today" regarding
circumvention.
- To go along with the above point,  providing a better review of existing
censorship circumvention techniques will help encourage building on
existing work, as opposed to re-inventing the wheel from first principles.
While perhaps this review should be a follow-up document, I strongly
encourage providing such a review, especially since the intended audience
is protocol designs.
- Within the draft itself, the discussion of censorship techniques is often
interwoven with circumvention methods. I suggest separating these concepts
out within each section. Instead of a "Tradeoffs" section, perhaps have
sections pertaining to "Cost to Implement to Censor", and "Techniques to
Circumvent", for improved clarity.
- One important point is that while China is an extremely powerful censor,
they are often in a class of their own. I encourage including a discussion
of something like "censor maturity" or the technical resources required to
implement different techniques. There is a bit of this discussion, but it
can be better standardized and applied to each technique. For example, IP
blacklisting is trivial and does not require significant infrastructure
(and many censors do this), but performing active probing to fingerprint
protocols and block them on the fly requires much more infrastructure and
planning (and is essentially only China, as I understand).

=== Specific Points ===
- DPI (deep packet inspection) is technically any kind of packet analysis
beyond IP address and port number- this concept can be better clarified.
Further, this technique is not specific to
- Clearly highlighting techniques that are thwarted by the use of TLS
versus techniques which can be performed even in spite of TLS usage would
also likely be helpful to readers.

Thanks,
Chelsea

On Wed, May 20, 2020 at 11:00 AM Christopher Wood <[e-mail]>
wrote:

> This is the research group last call for the "A Survey of Worldwide
> Censorship Techniques" (draft-irtf-pearg-censorship) draft available here:
>
>    https://datatracker.ietf.org/doc/draft-irtf-pearg-censorship/
>
> Please review the document and send your comments to the list by June 5,
> 2020. Feedback may also be sent to the GitHub repository located here:
>
>    https://github.com/IRTF-PEARG/rfc-censorship-tech
>
> Thanks,
> Chris, on behalf of the chairs
>
> --
> Pearg mailing list
> [e-mail]
> https://www.irtf.org/mailman/listinfo/pearg
>


-- 
Chelsea H. Komlo