On Cloudflare's blog, a senior research engineer shares a plan for "improving the trustworthiness of JavaScript on the web."
"It is as true today as it was in 2011 that Javascript cryptography is Considered Harmful."
The main problem is code distribution. Consider an end-to-end-encrypted messaging web application. The application generates cryptographic keys in the client's browser that lets users view and send end-to-end encrypted messages to each other. If the application is compromised, what would stop the malicious actor from simply modifying their Javascript to exfiltrate messages? It is interesting to note that smartphone apps don't have this issue. This is because app stores do a lot of heavy lifting to provide security for the app ecosystem. Specifically, they provide integrity, ensuring that apps being delivered are not tampered with, consistency, ensuring all users get the same app, and transparency, ensuring that the record of versions of an app is truthful and publicly visible.
It would be nice if we could get these properties for our end-to-end encrypted web application, and the web as a whole, without requiring a single central authority like an app store.
Further, such a system would benefit all in-browser uses of cryptography, not just end-to-end-encrypted apps. For example, many web-based confidential LLMs, cryptocurrency wallets, and voting systems use in-browser Javascript cryptography for the last step of their verification chains. In this post, we will provide an early look at such a system, called Web Application Integrity, Consistency, and Transparency (WAICT) that we have helped author. WAICT is a W3C-backed effort among browser vendors, cloud providers, and encrypted communication developers to bring stronger security guarantees to the entire web... We hope to build even wider consensus on the solution design in the near future....
We would like to have a way of enforcing integrity on an entire site, i.e., every asset under a domain. For this, WAICT defines an integrity manifest, a configuration file that websites can provide to clients. One important item in the manifest is the asset hashes dictionary, mapping a hash belonging to an asset that the browser might load from that domain, to the path of that asset.
The blog post points out that the WEBCAT protocol (created by the Freedom of Press Foundation) "allows site owners to announce the identities of the developers that have signed the site's integrity manifest, i.e., have signed all the code and other assets that the site is serving to the user... We've made WAICT extensible enough to fit WEBCAT inside and benefit from the transparency components." The proposal also envisions a service storing metadata for transparency-enabled sites on the web (along with "witnesses" who verify the prefix tree holding the hashes for domain manifests).
"We are still very early in the standardization process," with hopes to soon "begin standardizing the integrity manifest format. And then after that we can start standardizing all the other features. We intend to work on this specification hand-in-hand with browsers and the IETF, and we hope to have some exciting betas soon. In the meantime, you can follow along with our transparency specification draft,/A>, check out the open problems, and share your ideas."
Read more of this story at Slashdot.
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