Re: Last Call: <draft-nottingham-safe-hint-05.txt> (The "safe" HTTP Preference) to Proposed Standard

[Joseph Lorenzo Hall <[e-mail]>]

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On 11/16/14, 7:12 PM, Mark Nottingham wrote:
> Hi Joe,
> 
> Thanks for the substantive comments. Responses (hopefully equal in
> substance) inline.
> 
>> On 14 Nov 2014, at 4:19 am, Joseph Lorenzo Hall <[e-mail]>
>> wrote:
>> 
>> Signed PGP part
>> 
>> Hi, mnot has already heard the following concerns from us at CDT
>> about this spec, but we want to make sure that these are part of
>> the IETF last call comment record.
>> 
>> * The "Safe" preference is not only a preference but a signal.
>> It signals user vulnerability; when activated, the header would
>> signal a user's potentially vulnerable status not only to site
>> operators who intend to reply in good faith, but to those that
>> will operate in bad faith and also to every intermediary on-path
>> that could read the preference request.
>> 
>> Details about an Internet user's vulnerabilities should be
>> treated as sensitive information.  A broadcast signal that
>> advertises a user's content preferences or restrictions can
>> signal her youth, cognitive ability, relative media illiteracy,
>> technological inexperience, or another potential vulnerable
>> status.  Because of the risk that this information could be used
>> to exploit immature or inexperienced users, CDT generally
>> cautions against widespread identification of user vulnerability.
>> Obviously, sending such a preference inside an encrypted
>> connection removes concerns about on-path observers, but not the
>> more general concern with bad faith endpoints or other embedded
>> endpoints that may have other interests (e.g., advertisers on a
>> service may use this signal to profile vulnerable populations).
> 
> This is definitely a concern, and one of the big reasons that it's
> restricted to one bit.
> 
> However, as pointed out, while it could indicate a vulnerable user,
> "safe" is also usable by others; anecdotally, many people turn
> "safe" mode on in search engines out of personal preference, not
> because they're children or otherwise vulnerable.

I think any intentional use of this signals some level of
vulnerability. It could almost in part be flippantly called the
"troll-me" bit, as sending unsafe content conditioned on this flag
would almost always give rise to an emotional response on the part of
the user.

(Incidentally, if something outside the browser inserts this header it
may be very difficult for the user to actually turn off, as well. I'm
not sure if that's something you've thought about. In DNT, there are
applications you can install that will insert that header for you on
each request (AVG does this).)

> Additionally, "safe" is by no means a complete solution; it is not
> designed to be a filtering technology, nor to protect users from
> tracking / targeting; to attempt that it needs to be used in
> conjunction with other technologies (e.g., filters, ad blockers,
> tracker blockers, DNT -- although there is much debate about the
> effectiveness of these technologies as well).

Hmmm, it is definitely a "filtering preference technology", and the
desperate interpretations of the other endpoint as to what "safe" will
mean seems to set up more opportunity for confusion... not the
characteristic of a good standard, IMO.

> The draft already mentions most of this, and I'm happy to
> strengthen that text if you think it will help.
> 
> 
>> * Further, the ability for other intermediaries with access to
>> the request stream to insert the preference, potentially without
>> notice to the user, means that users may not even be aware that
>> they are broadcasting potentially sensitive information about
>> themselves, thus limiting their ability to take self-protective
>> measures against potential abuse.
> 
> Yes, this is possible.
> 
> The question, to me, is whether this potential abuse is outweighed
> by the potential benefit, and whether there are ways to mitigate
> the abuse.

Unfortunately, the forums in which to counteract abuse of this kind of
thing are as varied as the interpretations of "safe". :/ We see the
potential for badness as not just being abuse but more importantly
sites responding very differently to a standardized semantic signal.

Anyway, sorry to go around in circles here.

> Side story - When I was in Istanbul for IGF in September, I had a
> chat about "safe" with a well-respected researcher/advocate for
> online child safety. He was excited about it, because he had
> advocated something similar but much more bold to browsers in the
> past -- broadcasting the child's age bracket in requests.
> 
> Needless to say, that didn't happen, and I was surprised that
> someone with his knowledge and experience would consider putting
> such specific information in requests. I didn't ask at the time,
> but afterwards I surmise that he was implicitly relying on
> regulatory or legislative relief to assure that it wouldn't be
> abused.

Wowza!

> "safe" is by nature much more conservative than this -- it only
> reveals one bit of information, and that bit is not specific to any
> one group of users. If someone is adding it to your requests (a
> situation that should becoming more uncommon, if numbers about
> HTTPS adoption are to be believed), that's happening within a legal
> context that can offer relief as appropriate.
> 
> 
>> * As many of the comments in Last Call have identified, "Safe"
>> content in this specification is undefined. Because the proposal 
>> (necessarily) lacks a definition of "safe", it is unlikely to be 
>> useful to parents/guardians/users.  The lack of definition will 
>> produce diverse and conflicting interpretations from content
>> hosts and providers, which can mislead users and their guardians,
>> and may invite abuse and confusion.
>> 
>> The absence of guidance to websites wishing to participate in
>> "safe" content delivery will lead to varied and sometimes
>> contradictory results.  This could sow confusion and potential
>> conflict among participating platforms and website operators, and
>> undermine the utility of the specification.
>> 
>> Moreover, users and their parents will have diverse expectations 
>> about "safe" content.  These expectations will vary considerably 
>> with users' age, as well as parent/guardians' cultural
>> backgrounds. Without a common understanding of what qualifies as
>> "safe" content, the expectations of users and their
>> parent/guardians are likely to be frustrated.  Of course, it is
>> far outside the scope of a technical specification to define a
>> content-label like "safe".  But because a standardized definition
>> of "safe" content is unattainable, the specification will have
>> limited use as a tool for empowering parents to regulate and
>> guide their children's Internet use.
> 
> Again, "safe" is not a filtering technology; it is only
> pre-configuring the site's 'safe' mode if it has one, by the rules
> of that site. Whether or not that site's definition of 'safe' is
> appropriate to the user is a separate decision, one that might be
> enforced by a filter or some other mechanism.
> 
> In common deployments, I think it's best to view it as an extension
> of a Web filter *into* the site.
> 
> As above, I'm happy to expand / strengthen text here if you think
> it will help.
> 
> BTW, if the utility of the specification is indeed undermined as
> you point out, I think that's a largely self-correcting situation;
> lack of utility certainly hasn't stopped the IETF from making
> something a standard in the past.
> 
> Thanks again,
> 
> -- Mark Nottingham   https://www.mnot.net/
> 

- -- 
Joseph Lorenzo Hall
Chief Technologist
Center for Democracy & Technology
1634 I ST NW STE 1100
Washington DC 20006-4011
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