Adds a privacy and security review for TAG

PRIVACY_AND_SECURITY.md

@@ -0,0 +1,81 @@
+# Answers to [Security and Privacy Questionnaire](https://www.w3.org/TR/security-privacy-questionnaire/)
+
+### 3.1 Does this specification deal with personally-identifiable information?
+
+No.
+
+
+### 3.2 Does this specification deal with high-value data?
+
+No.
+
+
+### 3.3 Does this specification introduce new state for an origin that persists across browsing sessions?
+
+No.
+
+
+### 3.4 Does this specification expose persistent, cross-origin state to the web?
+
+No.
+
+### 3.5 Does this specification expose any other data to an origin that it doesn’t currently have access to?
+
+No.
+
+### 3.6 Does this specification enable new script execution/loading mechanisms?
+
+No.
+
+
+### 3.7 Does this specification allow an origin access to a user’s location?
+
+No.
+
+
+### 3.8 Does this specification allow an origin access to sensors on a user’s device?
+
+No.
+
+
+### 3.9 Does this specification allow an origin access to aspects of a user’s local computing environment?
+
+No.
+
+
+### 3.10 Does this specification allow an origin access to other devices?
+
+No.
+
+
+### 3.11 Does this specification allow an origin some measure of control over a user agent’s native UI?
+
+Yes. This specification will allow an origin to set a numerical badge in an OS specific location.
+
+
+### 3.12 Does this specification expose temporary identifiers to the web?
+
+No.
+
+
+### 3.13 Does this specification distinguish between behavior in first-party and third-party contexts?
+
+Yes. Only first parties are able to set a badge.
+
+### 3.14 How should this specification work in the context of a user agent’s "incognito" mode?
+
+This API will be no-ops in incognito mode.
+
+### 3.15 Does this specification persist data to a user’s local device?
+
+No.
+
+
+### 3.16 Does this specification have a "Security Considerations" and "Privacy Considerations" section?
+
+Yes. See the [explainer](explainer.md#security-and-privacy-considerations).
+
+
+### 3.17 Does this specification allow downgrading default security characteristics?
+
+No.

explainer.md

@@ -270,3 +270,7 @@ showing a large number, presenting several issues:
 However, the only solution to this is a much more limited API which only lets
 you show the count of notifications (or similar). We wanted to give apps the
 full power of showing a native badge.
+
+### Security and Privacy Considerations
+The API is set only, so data badged can't be used to track a user. Whether the API is present could possibly be used as a bit of entropy to fingerprint users, but this is the case for all new APIs.
+