Security FAQ (#2069)

* add stub of security FAQ document

* add basics to security FAQ

SECURITY.md

@@ -0,0 +1,60 @@
+# GitHawk Security FAQ
+
+## How does GitHawk authenticate access to repositories?
+
+GitHawk requests a GitHub OAuth token with the `repo`, `user`, and
+`notifications` scopes. According to the GitHub
+[documentation](https://developer.github.com/apps/building-oauth-apps/understanding-scopes-for-oauth-apps/),
+these scopes allow read/write access to profile information, read access to
+the authenticated user's notifications, and read/write access to code and
+commit messages for all public and private repositories to which the
+authenticating user has access.
+
+## How does GitHawk store passwords?
+
+By using OAuth, GitHawk avoids needing to store any passwords on the device or
+in the cloud.
+
+## How does GitHawk store authentication tokens?
+
+GitHawk stores an OAuth session token on the device in order to maintain the user's
+OAuth session across multiple runs of the app. This token has an expiry and is
+never uploaded to any servers.
+
+## Does GitHawk store source code?
+
+GitHawk stores some repository information on the device, including source
+code, pull request contents, and issue contents. This information is stored
+for the purpose of speeding up the app's user experience and reducing the
+nuber of redundant calls it needs to make to the GitHub API. Source code and
+other information downloaded using the `repo` OAuth scope is never uploaded to
+any servers.
+
+## When does GitHawk read source code from my repository?
+
+GitHawk reads source code from repositories only in the form of pull request
+diffs. Git patches, which contain multiple versions of relevant source code
+snippets, are read via GitHub API requests when the user asks to read the code
+corresponding to a given pull request. GitHawk does not read repo source code
+at any other time.
+
+## Does GitHawk ever clone my repositories?
+
+GitHawk does not clone Git repositories for any reason. All repo-specific
+information is acquired via OAuth-authenticated requests to the GitHub API.
+
+## When does GitHawk write to repositories?
+
+GitHawk writes to repositories only at the user's request. This includes
+actions like commenting on an issue or merging a pull request. GitHawk never
+writes to repositories without some explicit form of user confirmation
+immediately preceding the action.
+
+## What data does GitHawk upload to non-GitHub servers?
+
+GitHawk does not upload any information gathered via the GitHub API to
+third-party servers.
+
+## Are logs kept on who accesses what data via GitHawk?
+
+Logs are kept locally on the device for the purpose of debugging.