- From: Harry Halpin <hhalpin@w3.org>
- Date: Tue, 16 Aug 2016 21:52:18 +0200
- To: public-html-media@w3.org
- Message-ID: <f4804c8e-5fba-179c-e4ba-bf597e0385e3@w3.org>
On 08/16/2016 08:50 PM, Mark Watson wrote:
>
>
> On Tue, Aug 16, 2016 at 10:49 AM, Harry Halpin <hhalpin@w3.org
> <mailto:hhalpin@w3.org>> wrote:
>
>
>
> On 08/16/2016 07:46 PM, Mark Watson wrote:
>>
>>
>> On Tue, Aug 16, 2016 at 10:36 AM, Harry Halpin <hhalpin@w3.org
>> <mailto:hhalpin@w3.org>> wrote:
>>
>>
>>
>> On 08/16/2016 07:28 PM, David Singer wrote:
>> >> On Aug 16, 2016, at 10:22 , Harry Halpin <hhalpin@w3.org
>> <mailto:hhalpin@w3.org>> wrote:
>> >>
>> >>
>> >>
>> >> On 08/16/2016 06:35 PM, David Singer wrote:
>> >>> I think you’ll need to explain why the choice of how
>> much, and how, the user is warned, needs to be made by
>> you/us, and not by the browser maker. You also haven’t given
>> details of the ‘user harm’ you talk about for EME itself.
>> >> The details of 'user harm' are adequately explained by the
>> concerns over
>> >> the DMCA and the use of DRM that have been well-documented
>> elsewhere
>> >> [1].
>> > No, those criticisms were almost exclusively focused on the
>> risk to security researchers. Not one of the sub-headings you
>> link to appears to apply to users. Current politics
>> notwithstanding, repeatedly stating something doesn’t
>> intrinsically make it true.
>>
>> I don't agree. Insofar as security researchers cannot audit the
>> security of DRM systems, then it is *users* who will face any
>> harm due
>> to the lack of security audits. That is a unique feature of
>> DRM that EME
>> enables. EME can also, due to clearkey, be considered a
>> DMCA-compliant
>> system itself (i.e. clearKey's Key System is equivalent to a
>> CDM).
>>
>> >
>> >> Any installation or use of software that is compliant with
>> the DMCA
>> >> can be considered a risk to users and security researchers
>> as is noted
>> >> on WIkipedia [1].
>> > Users and security researchers are not the same people.
>>
>> See above.
>>
>> >
>> >> Although the FO is filed as an individual, one task of W3C
>> is to assure
>> >> there is representation of the interest of users and to
>> ensure the Web
>> >> is secure.
>> > Sure, but you need to say what the *user* harm is.
>>
>> If there is a part of a browser that makes security research
>> difficult
>> and possibly illegal, then that part of the browser is rather
>> self-evidently dangerous to end-users.
>>
>>
>> Unless the browser implementor takes additional measures to
>> compensate for that difficulty / possible illegality.
>
> I really do appreciate the work by this WG to compensate, but I do
> not think they are sufficient without 'off by default.' We can
> agree to disagree here, and let the WG make a decision and pass it
> to the Director. In that case, the FO still stands.
>>
>>
>> While I appreciate the effort,
>> sandboxing may help but there is no such thing as a perfect
>> sandbox.
>>
>>
>> There is no such thing as a perfect security audit either. We're
>> talking about different kinds of risk reduction.
>>
>
> Agreed. However, the DMCA provides a 'chilling effect' on security
> audits and research on DRM systems in general, regardless of the
> particular details of an audit or research.
>
>
> But there are things that can be done to compensate for the risk that
> any such effects cause. Sandboxing and strict input / output
> validation is one thing. Funding additional security audits could be
> another. Actively encouraging independent security research into that
> component is another.
Again, I really do appreciate the effort put into sandboxing and this
spec in general. That being said, no sandboxing or validation is
perfect, which is an argument to turn it off by default. Thus, since I
consider validation and sandboxing necessary but not sufficient, the FO
still stands.
In terms of protecting security researchers, the EFF has a proposition
but I am unclear if there is another one actively being discussed by the
WG. I am not a legal expert so I would suggest that Wendy and the legal
depts. of various W3C members try to sort something out. However, even
in the case that the EFF covenant or some other idea (and those
suggested are all good ideas), it seems *off by default* is sensible.
I do not know how much this would cause a problem with usability, but I
doubt it would cause much of a problem for those that do not have any
issues with DRM enabled content (i.e. they would click 'yes, please
activate'), but it would at least allow users to opt-out if they are so
concerned *before* becoming at risk to the security vulnerabilities
inherent in DRM. The same choice was made around the controversy in
Geolocation API and the WG sided with off-by-default, so I would expect
this WG to do the same.
To be clear, even in the case a legal resolution is made, the FO still
stands until EME is *off by default.*
>
>
>
>
>>
>> >
>> >> So, I think the decision should be made by the Working Group
>> >> with the best interests of users in mind, not just the
>> browser makers.
>> >> While you can consider 'off by default' to be
>> unreasonable, I think if
>> >> one takes that this same approach has been adopted by
>> similarly
>> >> controversial APIs (Geolocation API), I think it's quite
>> reasonable.
>> >>
>> >> cheers,
>> >> harry
>> >>
>> >> [1]
>> >>
>> https://en.wikipedia.org/wiki/Digital_Millennium_Copyright_Act#Criticisms
>> <https://en.wikipedia.org/wiki/Digital_Millennium_Copyright_Act#Criticisms>
>> >>
>> >>>
>> >>>> On Aug 16, 2016, at 4:28 , Harry Halpin <hhalpin@w3.org
>> <mailto:hhalpin@w3.org>> wrote:
>> >>>>
>> >>>>
>> >>>>
>> >>>> On 08/13/2016 05:05 PM, Paul Cotton wrote:
>> >>>>> Note that I am responding to an email and proposal from
>> Harry from earlier in this thread.
>> >>>>>
>> https://lists.w3.org/Archives/Public/public-html-media/2016Aug/0005.html
>> <https://lists.w3.org/Archives/Public/public-html-media/2016Aug/0005.html>
>> >>>>>
>> >>>>>> The text I would add to the EME spec would be similar:
>> >>>>>> "A conforming implementation of this specification
>> MUST ensure that this
>> >>>>>> API cannot be used without the user's express
>> permission due to the
>> >>>>>> inherent risks in the activation of a CDM in a user
>> agent. The API MUST
>> >>>>>> be disabled by default, and should only be activated
>> when the user gives
>> >>>>>> express consent and is fully informed on a per-origin
>> basis."
>> >>>>> This request would appear to be (at least partially)
>> covered by the existing text in the EME CR:
>> >>>>>
>> http://www.w3.org/TR/encrypted-media/#navigator-extension-requestmediakeysystemaccess
>> <http://www.w3.org/TR/encrypted-media/#navigator-extension-requestmediakeysystemaccess>
>> >>>>>
>> >>>>> 3.1.1 Methods
>> >>>>> requestMediaKeySystemAccess
>> >>>>> Note
>> >>>>>
>> >>>>> Calling this method may have user-visible effects,
>> including requests for user consent. This method should only
>> be called when the author intends to create and use a
>> MediaKeys object with the provided configuration.
>> >>>>> Requests access to the specified Key System. When
>> supportedConfigurations is specified, the configuration
>> specified by at least one of its elements must be supported.
>> The resulting MediaKeySystemAccess will correspond to the
>> first such element.
>> >>>>> Any permission checks or user interaction, such as a
>> prompt, MUST be performed before resolving the promise.
>> >>>>> Were you aware of this text in the EME specification?
>> Can you live with the current text since changing this text
>> to be normative and changing it to a MUST (I believe) would
>> be a “breaking change” and would require that we re-publish
>> another EME CR?
>> >>>>>
>> >>>>> /paulc
>> >>>>> HME WG Chair
>> >>>> Paul,
>> >>>>
>> >>>> Thanks for noting 'use-visible effects' but it does not
>> either explicitly 1) require a user-visible effect for fully
>> informing the user" and "gaining their consent" as well
>> "turning off EME by default". Simply put, the text you are
>> noting says MAY have user-visible effects and as so is too
>> weak to include in a test-suite or support EME being off by
>> default. So, it does not cover my objection, which
>> normatively requires much stronger text, including "off by
>> default". So, no I can't live with that text and require the
>> change (or a semantically equivalent one) that I suggest in
>> the github repo and e-mail list:
>> >>>>
>> >>>> https://github.com/w3c/encrypted-media/issues/304
>> <https://github.com/w3c/encrypted-media/issues/304>
>> >>>>
>> >>>> Thus, my formal objection still stands.
>> >>>>
>> >>>> cheers,
>> >>>> harry
>> >>>>
>> >>>>>
>> >>>>> From: Harry Halpin [mailto:hhalpin@w3.org
>> <mailto:hhalpin@w3.org>]
>> >>>>> Sent: Tuesday, August 2, 2016 5:00 AM
>> >>>>> To: public-html-media@w3.org
>> <mailto:public-html-media@w3.org>
>> >>>>> Subject: Re: Formal objection to Encrypted Media
>> Extensions progressing to Proposed Recommendation without
>> greater user protection
>> >>>>>
>> >>>>>
>> >>>>>
>> >>>>>
>> >>>>> On 08/02/2016 03:00 AM, Paul Cotton wrote:
>> >>>>>> An individual who registers a Formal Objection should
>> cite technical arguments and propose changes that would
>> remove the Formal Objection;
>> >>>>>
>> http://www.w3.org/2015/Process-20150901/#WGArchiveMinorityViews
>> <http://www.w3.org/2015/Process-20150901/#WGArchiveMinorityViews>
>> >>>>>
>> >>>>> Before I record your formal objection at [1] I would
>> like to ensure that your “proposed change” for your objection
>> is understood.
>> >>>>>> There is prior art in HTML for similarly powerful and
>> privacy-invasive features such as the Geolocation API [4].
>> Thus, there should be no procedural problem in requiring user
>> consent and disabling EME by default in all browsers.
>> >>>>> The reference you provide as a “prior art” precedent in
>> [4] is in a non-normative section of Geolocation API and it
>> does NOT disable the Geolocation API by default. Can you
>> explain why you think this reference is useful here? Are you
>> suggesting similar text be added to EME? If so could you
>> suggest exact text that would remove your formal objection?
>> >>>>>
>> >>>>> The exact phrasing is " A conforming implementation of
>> this specification must provide a mechanism that protects the
>> user's privacy and this mechanism should ensure that no
>> location information is made available through this API
>> without the user's express permission"
>> >>>>>
>> >>>>> To clarify, I agree that the spec should have used
>> capitalization: " A conforming implementation of this
>> specification MUST provide a mechanism that protects the
>> user's privacy and this mechanism should ensure that no
>> location information is made available through this API
>> without the user's express permission."
>> >>>>>
>> >>>>> However, I do believe that all browsers *do* indeed ask
>> for user consent before using the Geolocation API and that it
>> is disabled by default, which is clear prior art for EME.
>> This is indeed the case on the browsers I use, but if others
>> activate Geolocation API without user consent, please do
>> inform me, as I don't use Microsoft products.
>> >>>>>
>> >>>>> The text I would add to the EME spec would be similar:
>> >>>>>
>> >>>>> "A conforming implementation of this specification MUST
>> ensure that this API cannot be used without the user's
>> express permission due to the inherent risks in the
>> activation of a CDM in a user agent. The API MUST be disabled
>> by default, and should only be activated when the user gives
>> express consent and is fully informed on a per-origin basis."
>> >>>>>
>> >>>>> Given there is already a place where user consent MUST
>> be asked in the EME spec (" User agents must ensure that
>> users are fully informed and/or give explicit consent before
>> Distinctive Identifier(s) are exposed, such as in messages
>> from the Key System implementation"), there is no reason why
>> this MUST can't be broadened. I would also remove the "or."
>> The user must be fully informed AND give explicit consent.
>> >>>>>
>> >>>>> Furthermore, given this normative, testing for express
>> user consent on a per-origin basis should be part of the
>> test-suite.
>> >>>>>
>> >>>>> cheers,
>> >>>>> harry
>> >>>>>
>> >>>>>
>> >>>>>
>> >>>>>
>> >>>>>
>> >>>>> /paulc
>> >>>>> HME WG Chair
>> >>>>>
>> >>>>> [1]
>> https://dev.w3.org/html5/status/formal-objection-status.html
>> <https://dev.w3.org/html5/status/formal-objection-status.html>
>> >>>>>
>> >>>>> From: Harry Halpin [mailto:hhalpin@w3.org
>> <mailto:hhalpin@w3.org>]
>> >>>>> Sent: Monday, August 1, 2016 6:42 PM
>> >>>>> To: public-html-media@w3.org
>> <mailto:public-html-media@w3.org>
>> >>>>> Subject: Formal objection to Encrypted Media Extensions
>> progressing to Proposed Recommendation without greater user
>> protection
>> >>>>>
>> >>>>> [Note this is a formal objection as an individual in a
>> private capacity, not on behalf of my organization]
>> >>>>>
>> >>>>> I'd like to fill a formal objection against Encrypted
>> Media Extensions progressing to Proposed Recommendation
>> status without adequate protection for users.
>> >>>>>
>> >>>>> I believe that this work is so problematic given the
>> well-known and well-documented problems with DRM, it should
>> not happen as a standard at all at W3C. That being said, for
>> reasons which I do not agree with and hope he reconsiders,
>> the Director has approved both the scope of the charter and
>> the move of the Working Draft to Candidate Recommendation.
>> >>>>>
>> >>>>> If it does happen, then it seems given the
>> well-documented problems, some harm mitigation should be
>> pursued. The security research community has broad support
>> for the EFF covenant being a normative requirement [1].
>> However, it appears consensus is not forthcoming on either
>> EME itself or the EFF covenant, with the Technology and
>> Policy IG also failing to gain any consensus for even further
>> discussion (as it failed to even get chartered).
>> >>>>>
>> >>>>> To myself, the danger of EME is that over the last year
>> suddenly over millions of people had a content decryption
>> module installed without their explicit consent on their
>> computer. For many users, such as those of Firefox, the DCM
>> was installed via a silent update they had no control over.
>> Such a content decryption module can serve as both a
>> technical security risk, as it puts a highly privileged
>> process in the user's computer outside their direct control
>> by design, and as a legal risk subjects any inspection of the
>> DRM-enabled system on their computer due to the
>> anti-circumvention provision of the DMCA or local equivalent.
>> Thus, regardless of whether or not one agrees with EME, it
>> seems the *least* the W3C should do is warn the user about
>> the installation and activation of a CDM on their machine -
>> and that the CDM should not be installed and EME should not
>> be activated without explicit user consent. Thus, in all
>> configurations, EME should be *de-activated by default.*
>> >>>>>
>> >>>>> There is prior art in HTML for similarly powerful and
>> privacy-invasive features such as the Geolocation API [4].
>> Thus, there should be no procedural problem in requiring user
>> consent and disabling EME by default in all browsers. While
>> it can be argued many users will want to watch protected
>> videos and will turn them on, just as many users will want to
>> use Google Maps with Geolocation APIs, there does not seem to
>> be a reasonable case for having such
>> >>>>> powerful and possibly dangerous features enabled by
>> default.
>> >>>>>
>> >>>>> Current language in the spec is so weak as it may not
>> be enforced and so EME does not have to be disabled by
>> default: " User Agents have some flexibility to determine
>> whether consent is required for a specific configuration and
>> whether such consent may also apply to other configurations.
>> For example, consent to one configuration may also imply
>> consent for less powerful, more restricted configurations.
>> Equally, a denial of consent for one configuration may imply
>> denial of consent for more powerful, less restricted
>> configurations."
>> >>>>>
>> >>>>> The only place where the spec [5] makes normative
>> statements around consent, but due to how DRM (i.e. Key
>> Systems) are designed, it is unclear how the user agent
>> should interpret these statements
>> >>>>>
>> >>>>> "If a user agent chooses to support a Key System
>> implementation that cannot be sufficiently sandboxed or
>> otherwise secured, the user agent should ensure that users
>> are fully informed and/or give explicit consent before
>> loading or invoking it."
>> >>>>>
>> >>>>> "User Agents should ensure that users are fully
>> informed and/or give explicit consent before a Key System
>> that presents security concerns that are greater than other
>> user agent features (e.g. DOM content) may be accessed by an
>> origin..."
>> >>>>>
>> >>>>> " User agents must ensure that users are fully informed
>> and/or give explicit consent before Distinctive Identifier(s)
>> are exposed, such as in messages from the Key System
>> implementation."
>> >>>>>
>> >>>>> Although these statements show some progress towards
>> trying to mitigate the dangers of DRM, given that DRM systems
>> work in conjunction with anti-circumvention legislation that
>> prevents a developer from knowing whether or not they can
>> sufficiently sandboxed (or 'otherwise secured') and whether a
>> Distinctive Identifier is used by the DRM system, so the use
>> of EME will *always* present security concerns that are
>> greater than the rest of the user agent features involving
>> the Open Web Platform.
>> >>>>>
>> >>>>> Is the Working Group amendable to having EME and
>> associated DRM systems (i.e. "Key Systems") *normatively*
>> disabled by default in order to protect users?
>> >>>>>
>> >>>>> cheers,
>> >>>>> harry
>> >>>>>
>> >>>>> [1]
>> https://www.eff.org/deeplinks/2016/03/security-researchers-tell-w3c-protect-researchers-who-investigate-browsers
>> <https://www.eff.org/deeplinks/2016/03/security-researchers-tell-w3c-protect-researchers-who-investigate-browsers>
>> >>>>> [2]
>> https://en.wikipedia.org/wiki/Digital_rights_management#Opposition_to_DRM
>> <https://en.wikipedia.org/wiki/Digital_rights_management#Opposition_to_DRM>
>> >>>>> [3]
>> https://en.wikipedia.org/wiki/Digital_rights_management#Shortcomings
>> <https://en.wikipedia.org/wiki/Digital_rights_management#Shortcomings>
>> >>>>> [4]
>> https://www.w3.org/TR/geolocation-API/#implementation_considerations
>> <https://www.w3.org/TR/geolocation-API/#implementation_considerations>
>> >>>>> [5] https://w3c.github.io/encrypted-media/
>> <https://w3c.github.io/encrypted-media/>
>> >>>>>
>> >>> David Singer
>> >>> Manager, Software Standards, Apple Inc.
>> >>>
>> >>
>> >>
>> > David Singer
>> > Manager, Software Standards, Apple Inc.
>> >
>>
>>
>>
>
>
Received on Tuesday, 16 August 2016 19:52:27 UTC