The problem

Google's "Manifest V3" ongoing API changes are severely hampering browser extensions in their ability to  block unwanted content and to enforce additional security policies, threatening the usefulness, if not to the very existence, of many popular privacy and security tools. uBlock's developer made clear that this will cause him to cease supporting Chromium-based browsers. Also EFF (which develops extensions such as HTTPS Everywhere and Privacy Badger) publicly stigmatized Google's decisions, questioning both their consequences and their motivations.

NoScript is gravely affected too, although its position is not as dire as others': in facts, I've finished porting it to Chromium-based browsers in the beginning of 2019, when Manifest V3 had already been announced. Therefore, in the late stages of that project and beyond, I've spent considerable time researching and experimenting alternate techniques, mostly based on standardized Web Platform APIs and thus unaffected by Manifest V3, allowing to implement comparable NoScript functionality albeit at the price of added complexity and/or performance costs. Furthermore Mozilla developers stated that, even though staying as much compatible as possible with the Chome extensions API is a goal of theirs, they do not plan to follow Google in those choices which are more disruptive for content blockers (such as the deprecation of blocking webRequest).

While this means that the future of NoScript is relatively safe, on Firefox and the Tor Browser at least, the browser extensions APIs and capabilities are going to diverge even more: developing and maintaining a cross-browser extension, especially if privacy and/or security focused, will become a complexity nightmare, and sometimes an impossible puzzle: unsurprisingly, many developers are ready to throw in the towel.

What would I do?

The collection of alternate content interception/blocking/filtering techniques I've experimented with and I'm still researching in order to overcome the severe limitations imposed by Manifest V3, in their current form are best defined as "a bunch of hacks": they're hardly maintainable, and even less so reusable by the many projects which are facing similar hurdles. What I'd like to do is to refine, restructure and organize them into an open source NoScript Commons Library. It will provide an abstraction layer on top of common functionality needed to implement in-browser security and privacy software tools.

The primary client of the library will be obviously NoScript itself, refactored to decouple its core high-level features from their browser-dependent low-level implementation details, becoming easier to isolate and manage. But this library will also be freely available (under the General Public License) in a public code repository which any developer can reuse as it is or improve/fork/customize according to their needs, and hopefully contribute back to.

What do I hope?

Some of the desired outcomes:

• By refactoring its browser-dependent "hacks" into a Commons Library, NoScript manages to keep its recently achieved cross-browser compatibility while minimizing the cross-browser maintenance burden and the functionality loss coming from Manifest V3, and mitigating the risk of bugs, regressions and security flaws caused by platform-specific behaviors and unmanageable divergent code paths.
• Other browser extensions in the same privacy/security space as NoScript are offered similar advantages by a toolbox of cross-browser APIs and reusable code, specific to their application domain. This can also motivate their developers (among the most competent people in this field) to scrutinize, review and improve this code, leading to a less buggy, safer and overall healthier privacy and security browser extensions ecosystem.
• Clearly documenting and benchmarking the unavoidable differences between browser-specific implementations help users make informed choices based on realistic expectations, and pressure browser vendors into providing better support (either natively or through enhanced APIs) for the extensions-provided features which couldn't be optimized for their product. This will clearly outline, in a measurable way, the difference in commitment for a striving ecosystem of in-browser security/privacy solutions between Mozilla and other browser vendors, keeping them accountable.
• Preserving a range of safe browsing options, beyond Firefox-based clients, increases the diversity in the "safe browsing" ecosystem, making web-based attacks significantly more difficult and costly than they are in a Firefox-based Tor Browser mono-culture.

I want you!

Are you an extensions developer, or otherwise interested in in-browser privacy/security tools? I'd be very grateful to know your thoughts, and especially:

1. Do you think this idea is useful / worth pursing?
2. What kind of features would you like to see supported? For instance, content interception and contextual blocking, filtering, visual objects replacement (placeholders), missing behavior replacement (script "surrogates"), user interaction control (UI security)...
3. Would you be OK with a API and documentation styles similar to what we have for Firefox's WebExtensions?
4. How likely would you be to use such a library (either for an existing or for a new project), and/or to contribute to it?

Many thanks in advance for your feedback!

https://hackademix.net/2020/03/07/a-cross-browser-code-library-for-securityprivacy-extensions-interested/