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Explainer https://github.com/WICG/signature-based-sri Specification https://wicg.github.io/signature-based-sri Summary This feature provides web developers with a mechanism to verify the provenance of resources they depend upon, creating a technical foundation for trust in a site's dependencies. In short: servers can sign responses with a Ed25519 key pair, and web developers can require the user agent to verify the signature using a specific public key. This offers a helpful addition to URL-based checks offered by Content Security Policy on the one hand, and Subresource Integrity's content-based checks on the other. Blink component Blink>SecurityFeature Motivation To protect themselves from code injection, developers can restrict themselves to loading script from certain URLs and certain `<script>` elements (through Content Security Policy), and to loading script whose content is well-known (through Subresource Integrity). These satisfy a large number of use case, but fail to satisfy others (particularly supply chain integrity for dynamic resources). Signatures reasonably address this hole, nicely complementing the existing mechanisms. Initial public proposal https://github.com/w3c/webappsec/issues/449 Search tags sri, signature, ed25519, integrity, provenance TAG review None TAG review status Pending Risks Interoperability and Compatibility None Gecko: No signal (https://github.com/mozilla/standards-positions/issues/1139) WebKit: No signal (https://github.com/WebKit/standards-positions/issues/434) Web developers: No signals Shopify (@yoavweiss) has expressed positive initial impressions, as have folks at Cloudflare. Other signals: Ergonomics The hash functions we currently support for SRI generally are not conducive to streaming responses. This is arguably fine for scripts and stylesheets (as those are executed atomically, requiring the entire body), but it cannot work for other resource types (images, video, etc). It's likely we'll want to extend the set of hash functions in the future (though we'd do that for SRI, CSP, and this mechanism in one fell swoop). Security The feature aims to plug a security hole in the platform's status quo ante: it is impossible to deploy content-based integrity checks for dynamic resources, and URL-based checks are too broad to provide meaningful security protections. We continue to require CORS-based opt-in for integrity checks on responses to ensure that we're not leaking data unintentionally between origins. WebView application risks Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications? None Debuggability None Is this feature fully tested by web-platform-tests? Yes https://wpt.fyi/results/subresource-integrity/identity-digest?label=experimental&label=master&aligned https://wpt.fyi/results/subresource-integrity/signatures?label=experimental&label=master&aligned Flag name on about://flags signature-based-sri Finch feature name SignatureBasedIntegrity Requires code in //chrome? False Tracking bug https://issues.chromium.org/issues/375224898 Estimated milestones No milestones specified Link to entry on the Chrome Platform Status https://chromestatus.com/feature/5032324620877824?gate=5176565124825088 This intent message was generated by Chrome Platform Status. -- You received this message because you are subscribed to the Google Groups "blink-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to blink-dev+unsubscr...@chromium.org. To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/6753088f.2b0a0220.1432c2.020a.GAE%40google.com.
