When you log into your Firefox Account, you expect a seamless experience across all your devices. In the past, we weren’t doing the best job of delivering on that experience, because we didn’t have the tools to collect cross-product metrics to help us make educated decisions in a way that fulfilled our lean data practices and our promise to be a trusted steward of your data. Now we do.
Firefox 81 will include new telemetry measurements that help us understand the experience of Firefox Account users across multiple products, answering questions such as: Do users who set up Firefox Sync spend more time on desktop or mobile devices? How is Firefox Lockwise, the password-manager built into the Firefox desktop browser, used differently than the Firefox Lockwise apps? We will use the unique privacy features of Firefox Accounts to answer questions like these while staying true to Mozilla’s data principles of necessity, privacy, transparency, and accountability–in particular, cross-product telemetry will only gather non-identifiable interaction data, like button clicks, used to answer specific product questions.
We achieve this by introducing a new telemetry ping that is specifically for gathering cross-product metrics. This ping will include a pseudonymous account identifier or pseudonym so that we can tell when two pings were created by the same Firefox Account. We manage this pseudonym in a way that strictly limits the ability to map it back to the real user account, by using the same technology that keeps your Firefox Sync data private (you can learn more in this post if you’re curious). Without getting into the cryptographic details, we use your Firefox Account password as the basis for creating a secret key on your client. The key is known only to your instances of Firefox, and only when you are signed in to your Firefox account, and we use that key to generate the pseudonym for your account.
We’ll have more to share soon. As we gain more insight into Firefox, we’ll come back to tell you what we learn!