Contact emailsdavid...@chromium.org, dadr...@google.com ExplainerNone
Specificationhttps://datatracker.ietf.org/doc/html/draft-ietf-tls-esni Summary The TLS Encrypted ClientHello (ECH) extension enables clients to encrypt ClientHello messages, which are normally sent in cleartext, under a server’s public key. This allows websites to opt-in to avoid leaking sensitive fields, like the server name, to the network by hosting a special HTTPS RR DNS record. (Earlier iterations of this extension were called Encrypted Server Name Indication, or ESNI.) Blink componentInternals>Network>SSL <https://bugs.chromium.org/p/chromium/issues/list?q=component:Internals%3ENetwork%3ESSL> Search tagsech <https://chromestatus.com/features#tags:ech>, esni <https://chromestatus.com/features#tags:esni>, tls <https://chromestatus.com/features#tags:tls>, ssl <https://chromestatus.com/features#tags:ssl> TAG reviewNot applicable; this is a protocol under IETF TAG review statusNot applicable Risks Interoperability and Compatibility As a networking protocol, interoperability risks look different from a web platform API: This is a draft of a developing protocol, so the final standard will differ from what we ship now. We manage this as in other protocol work: the draft uses different codepoints in the DNS record and ClientHello, set up to not conflict with the final standard. There is also a risk of breaking buggy servers or network middleware. ECH is DNS-gated, so non-ECH servers won't be exposed to ECH itself. We do implement ECH's GREASE mechanism (section 6.2 of the draft), but this should appear as any normal unrecognized extension to non-ECH servers. Servers and network elements that are compliant with RFC 8446, section 9.3, should not be impacted. We will be monitoring for these issues as part of the experiment, comparing error rates and handshake times both for HTTPS servers as a whole, and the subset of those that advertise ECH in DNS. *Gecko*: In development ( https://blog.mozilla.org/security/2021/01/07/encrypted-client-hello-the-future-of-esni-in-firefox ) *WebKit*: No signal *Web developers*: Positive ( https://blog.cloudflare.com/encrypted-client-hello) *Other signals*: Ergonomics ECH is part of TLS, so it is largely abstracted away from web platform APIs themselves. Activation This is a network protocol and thus inherently requires server software changes. It also requires keys deployed in the HTTPS DNS record. At this stage in the process, we do not expect ECH to be deployed beyond a few early adopters. Rather, this experiment is part of real-world testing for the developing protocol. The connection with the DNS record is of particular note. It is possible that, due to DNS caching, etc., that the DNS record we fetch is out of sync with the server instance we talk to. ECH has a built-in recovery mechanism to repair these mismatches. One of the aims of the experiment will be to validate this mechanism. Security See https://datatracker.ietf.org/doc/html/draft-ietf-tls-esni-14#section-10 for security considerations in the specification 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? No WebView-specific risks Debuggability Servers that use ECH are visible in the DevTools security panel. Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, Chrome OS, Android, and Android WebView)?Yes While supported on all platforms, ECH requires keys fetched via DNS in the new HTTPS record. Chrome can currently fetch the HTTPS record over DoH and over our built-in DNS resolver. Is this feature fully tested by web-platform-tests <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md> ?No Flag name on chrome://flagsencrypted-client-hello Finch feature nameNone Non-finch justificationNone Requires code in //chrome?False Tracking bughttps://crbug.com/1091403 Launch bughttps://crbug.com/1349902 Availability expectationFeature is also being launched in Firefox. Sample links https://tls-ech.dev Estimated milestones Shipping on desktop 117 OriginTrial desktop last 116 OriginTrial desktop first 115 DevTrial on desktop 105 Shipping on Android 117 OriginTrial Android last 116 OriginTrial Android first 115 DevTrial on Android 105 Anticipated spec changes Open questions about a feature may be a source of future web compat or interop issues. Please list open issues (e.g. links to known github issues in the project for the feature specification) whose resolution may introduce web compat/interop risk (e.g., changing to naming or structure of the API in a non-backward-compatible way). n/a Link to entry on the Chrome Platform Status https://chromestatus.com/feature/6196703843581952 Links to previous Intent discussionsIntent to prototype: https://groups.google.com/a/chromium.org/g/blink-dev/c/YEo4LqB7nWI Intent to Experiment: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAF8qwaB488g2%3D1WdmFPnWaAYaXB2pXaVv0-Xe-XXqYFRi5y20A%40mail.gmail.com This intent message was generated by Chrome Platform Status <https://chromestatus.com/>. -- 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 on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAGkh42KgSdG0D1YT3H8EjXkm4zys4i5A1jskyZcXGbaedGvxHQ%40mail.gmail.com.
