talk-plugin-gravatar

Demo

A simple Talk plugin to display Talk users' Gravatar avatars with as much privacy as possible. The plugin acts as a proxy to gravatar and never directly reveal the md5sum of a talk user's email. This avoids two key privacy concerns normally faced when using gravatar:

1. Leaking emails via md5sums of said emails

By adding Gravatar image URLs to your site you are effectively leaking a lot of information. The md5sum itself will be searchable and might reveal which other sites the user registered for. md5sums are also trivially bruteforceable, and any reverse lookup databases of emails that have been part of databreaches will be even easier to look up.

2. Referer header passed to Gravatar

When a user's browser loads a Gravatar URL it will also send a referer header. This header will reveal the exact page from which the avatar was loaded. This info can be used by Gravatar to see which sites a user is posting on.

This plugin was inspired by the blog post How Gravatar hurts your visitors.

Caveats

Gravatar still learns the IP of the Talk instance being used for comments thus revealing which possible sites a user has commented on. The Fly.io solution does not suffer this problem as their proxy, or the one you host yourself, bears no direct conncetion to any sites. Another caveat is the added load being imposed on your Talk instance.

Installation

Add the plugin to the plugins.default.json file or create a plugins.json file and add it there. See the Coral Talk plugin docs for details about adding plugins.

Example plugins.json file:

{
  "server": [
    {"talk-plugin-gravatar": "^0.1.2"}
  ],
  "client": [
    {"talk-plugin-gravatar": "^0.1.2"}
  ]
}

Then run ./bin/cli plugins reconcile for source installs or an appropriate command for your talk installation to make the plugin available.

How the plugin works

The plugin works by adding an avatar property to the User type in the graphql schema. When the avatar property resolver is called it will check if the user model in the database contains an avatar value, if not an uuid is created and stored. Finally the avatar resolver will return the uuid.

Next the client Avatar component will add an img element to a comment referencing the plugin's avatar endpoint: <your-talk-domain>/avatar/:avatar. The request handler in the plugin will first check if the avatar with the given id is cached in Talk's Redis cache. Cached avatars are immediately returned. If an avatar is not cached the request handler will fetch it from Gravatar and then cache it for 24 hours. The request handler also returns an ETag header based on an md5sum of the avatar contents to save bandwith.

Caching is set to 24 hours expiry time to avoid hammering Gravatar with requests from the API.

Development

Fork this repository if you have not already done so. Then follow the Installation from source guide to get a local copy of Talk. Once you have a local talk folder enter the plugins directory and clone your forked repository:

$ cd plugins
$ git clone [email protected]:<youruser>/talk-plugin-gravatar.git

Add a plugins.json file with the following contents under the talk folder:

{
  "server": [
    "talk-plugin-gravatar"
  ],
  "client": [
    "talk-plugin-gravatar"
  ]
}

Make sure you have set up mongodb and redis correctly and have configured Talk according to the setup guide. Finally run the talk development script:

$ yarn watch

This will start the Talk server with the plugin enabled. You will have to go through the Talk installation steps before you can create some test comments and see the plugin in action.

Demonstration

See Github page