Status of This Document
This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.
This is the first public Working Group Note of the Device API Privacy Requirements. This document is expected to be further updated based on both Working Group input and public comments. The Working Group anticipates to
eventually publish a stabilized version of this document as a W3C
Working Group Note.
This document was published by the Device APIs and Policy Working Group. If you wish to make comments regarding this document, please send them to public-device-apis@w3.org (subscribe, archives). All feedback is welcome.
Publication as a Working Group Note does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.
This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.
1. Introduction
Privacy considerations are important to Device APIs, since misuse of information exposed by the APIs can have potentially harmful financial, physical safety, reputational and other impacts. Privacy needs a systemic solution that includes
functional requirements on user agents, web sites and other components
of the system, since any opportunity for misuse of private information
is a risk. Addressing privacy may include functional requirements in
technical standards, laws and regulations, and best practices.
While privacy is an important consideration for all APIs, privacy
risks may vary according to the information exposed by an individual
API. For example, inappropriate disclosure of contacts or location
information could create serious personal safety issues in a broad
range of cases, while disclosure of certain system information might
create privacy risks in fewer contexts.
1.1 Architectural Approach
Privacy is a broad topic with various aspects that involve
different parties in a system. In order to be clear which
aspects are addressed and how, we take an architectural
approach of breaking down the problem into smaller
pieces. This should provide clarity and enable
privacy-respecting solutions that can be adopted. We have
identified the following pieces:
- Defining APIs in such a way that they are as “naturally” privacy-respecting as possible
This is similar to writing APIs in such a way that they are
security-friendly; you can't
keep people from making mistakes, but you can make it easier
and more natural to be privacy-respecting through the API
design.
An example is supporting the concept of
Minimization by designing APIs
that return the minimum data needed for a task, such as
only obtaining address fields when an address is needed.
- Requiring from user agents what they can realistically enforce
User agents are crucial to ensuring that user privacy is protected, but this capability must take implementation and adoption considerations into account. User agent design decisions can be separated to a large degree from API design decisions.
- Empowering users to express privacy preferences
-
This can be hard to manage technically but might be possible through a simpler approach of defining and agreeing upon a small set of privacy preferences, similar to
Creative Commons copyright licenses, that users can attach to their data.
Defining a simple vocabulary
for privacy could enable privacy rulesets that can be
referenced by URI.
Other
people
have had this idea as well.
- Conducting education and outreach, similar to the accessibility efforts
WAI and the Web community at large have done a great job
raising awareness about accessibility
issues, and while implementations are not perfect, their effort has had a very
measurable impact. There is therefore experience to be
tapped in such an approach for the parts
of the problem that depend on convincing people to do the
right thing (which in some cases can be wide-ranging, including making script libraries support the solution directly, or having various organizations enforce it internally).
1.2 Privacy Principles relevant to APIs
Privacy protections are frequently understood as a set of
principles or elements (one such set is described in
[PRIVACY-ISSUES-GEO]). The core elements of privacy that are
relevant to Device APIs, user agents that support the APIs, and
applications that use the APIs are as follows:
Notice: Informing users about the data collected through Device APIs
Consent: Obtaining user agreement to sharing data through Device APIs
Minimization: Limiting the amount and level of detail of data collected through Device APIs
Control: Allowing users to control access to their data once they have consented to having it collected through Device APIs
Access: Providing users with access to information about the data that has been collected about them through Device APIs
Retention: Limiting how long applications retain data that was collected through Device APIs
Secondary
Use: Limiting applications from using data
collected through Device APIs for purposes other than the
purpose for which it was collected
Sharing: Limiting applications from sharing data collected through Device APIs with third parties
These elements will each need to be approached in different ways. Approaches include specific requirements
on individual APIs, conveying user expectations together with
the data itself, and/or documenting best practices for application
and content developers. Certain approaches are better suited to safeguarding certain privacy elements than others.
This document provides specific requirements for individual APIs, addressing the elements that are most relevant to API definitions: notice, consent, minimization, control, and access. Requirements involving user expectations, which primarily address retention, secondary use, and sharing, will be documented separately. Best practices for developers will also be documented separately, covering notice, minimization, control, access, retention, secondary use, and sharing in the application developer context.
The following table summarizes the breakdown of how each element is covered:
The privacy requirements for individual APIs are provided in the next section. The requirements described in this document are intended
to be applicable to device APIs both in the context of
widgets and web applications.
The breakdown described above foreshadows the idea of providing API hooks that allow users to attach their expectations/preferences/policies about privacy to the data they share through the APIs. Attaching policy rules to the data that get shared can provide a legal basis for enhancing the control users have
over their data once they are shared; but doing so create the
following challenges:
- getting the user to understand and set rules on sharing their information, and to understand that limits of those rules, is hard;
- if users set their preferences in the user agent, they may expect
the
user agent to enforce these preferences while it cannot actually control
the data flow once the data has been transmitted;
- developers may ignore policy rules sent along with the data they're actually interested in (at the risk of encountering legal or market consequences)
2. Requirements for API Definitions
Many of the requirements listed here are recommendations (SHOULDs) rather than absolute requirements (MUSTs). In many cases this is because making a requirement absolute is appropriate for only a subset of the APIs, but not every API. As appropriate, individual APIs may place stronger normative requirements on user agents than the requirements in this document place on APIs.
2.1 Notice
Making sure that users understand the implications of using an application that relies on a Device API is fundamental to ensuring the protection of their data. The following requirements can help to make sure that users are properly notified:
APIs must make it possible for user agents to notify users that their
data is being collected via the API. This notification must
identify the application (for example, by displaying its document
origin [HTML5]) and the precise data being collected.
APIs should provide support for visual indicator(s) that data
is being collected via the APIs.
Should the APIs have a hook for applications to
convey the intended usage of the data? If they do, should it be a
required parameter? And how can this information be conveyed without
misleading the user about the trustworthiness of that information?
2.2 Consent
The semantics of some APIs are defined such that user
interaction is essential to make use of the API. An example is
a camera API that enables the user to take a photograph, but
is defined to require the user to press a shutter key to take
the photograph. Another example
is an API that produces a message template, but requires the
user to press "send" to actually send the message.
Such user actions constitute implicit consent to
collection of data via the API, since the user has a choice
to perform these actions and doing so implies consent for
the application to access the associated Device
Capabilities. In such situations where it is obvious that
performing the action involves sharing data with the
application and the application’s intended use of the data
is also obvious, additional dialogs that prompt users for
consent may not be necessary.
Device APIs may also be defined such that consent must be explicit, not implicit. Examples are a camera API that takes a photograph without user involvement, or a messaging API that sends a message without the user pressing "send." In these cases dialogs may be required.
To ensure that data is not collected without users knowing or realizing, APIs should be designed with the presumption that the explicit consent model will be used, and should explain the specific circumstances under which implicit consent may be acceptable. This gives rise to the following requirements:
APIs must make it possible for user agents to obtain user
consent before sharing any data via the APIs.
APIs must be defined in such a way that explicit consent is assumed, and they should articulate the circumstances under which implicit consent is acceptable.
An important caveat to the consent model supported by Device APIs relates to data about other people that the user may have on his or her device and be able to share via the APIs (other people’s contact or calendar information, for example). A user should not be able to consent through the Device APIs to use of other people’s information beyond the original interaction with the API. Thus, for example, a user should be able to consent to have an application contact another person mentioned in a calendar entry (perhaps to say “I am running late”), but the user should not also be able to consent to have the application make later use of the person’s contact information (perhaps to send marketing messages to that person). This caveat should be conveyed where appropriate in the APIs, best practices, and other Device APIs documents.
2.3 Minimization
To reduce the risks of over-exposing users data, it is important to
design APIs so that Web developers can request as little information
as they need to accomplish their goals.
An example use case is a social networking case where the contacts
API is used to contacts who are also members of a
social network. Email addresses serve as the social network
handles. In this case limiting results to the addresses and not
other personal information is an example of minimization.
This gives rise to the following requirements:
APIs must make it easy to request as little information as
required for the intended usage.
For instance, an API call should require specific parameters to be
set to obtain more information, and should default to little or no
information.
APIs should make it possible for user agents to convey the
breadth of
information that the requester is asking for.
For instance, if a developer only needs to access a specific field
of a user address book, it should be possible to explicitly mark that
field in the
API call so that the user agent can inform the user that this single
field of data will be shared.
APIs should make it possible for user agents to let the user
select, filter, and transform information before it is shared with the requester.
The user agent can then act as a broker for trusted data, and will
only transmit data to the requester that the user has explicitly
allowed.
2.4 Control
Given the sensitivity of the data made available through Device APIs, it is important for users to be able to control which applications have access to that data. The following requirements ensure that (1) users have control over their data even after they have shared it with an application, and (2) users have robust controls over which applications can obtain their data to begin with:
APIs must make it possible for user agents to support the revocation
of user consent to sharing of data via the APIs.
APIs should support the ability for user agents to allow users to whitelist trusted applications and blacklist untrusted applications.
2.5 Access
Notice and control cannot be fully implemented unless users can review how they have shared data in the past. The following requirements suggest how APIs can support users’ access to this information:
APIs should make it possible for user agents to allow users to view the applications with whom they have shared data.
APIs should make it possible for user agents to allow users to view, edit, and delete the history of the user's data sharing with each.
3. Requirements related to User Expectations of Data Use
Users may have expectations of how their data is used, in
particular related to data retention, use for other purposes, and
sharing.
How applications specify how they plan to meet these expectations
(application policy), how users express their desires (user policy)
and constraints on data use may all be related to managing these
expectations. A license approach similar to Creative Commons may
offer a simple manner to address these requirements.
This section does not currently contain any requirements. Because retention, secondary use, and sharing are largely out of the control of the APIs, it's not entirely clear that it makes sense to have any API requirements about these aspects. On the other hand, one can envision a requirement that supports the ruleset model, such as:
Likewise, if we wanted the APIs to support applications' ability to convey their intended policies about these aspects, we could have a requirement like:
3.1 Retention
Retention is about to user expectations about how long data they
provide will be retained, and whether applications must dispose of
collected data after
fulfilling the purpose for which it was collected.
3.2 Secondary Use
Secondary Use is about to user expectations regarding whether
applications can use data for purposes other than that for which
the data was collected.
3.3 Sharing
Sharing is about user expectations on how data will be shared. Once
data have been made available to a requester, the
requester is in a position to store and redistribute these data, with
or without the user consent. Granularity of data shared is an
important aspect of sharing.