Intent to remove DHE ciphers from WebRTC DTLS handshake

[Nils Ohlmeier]

Summary:

We are looking at removing the DHE cipher suites from the DTLS handshake in Firefox soon.

Ciphers:
- TLS_DHE_RSA_WITH_AES_128_CBC_SHA
- TLS_DHE_RSA_WITH_AES_256_CBC_SHA
are the two suites which we want to remove, because they are considered too weak.

A Telemetry probe landed in Firefox 63 Nightly to monitor the usage of the different cipher suites:
https://telemetry.mozilla.org/new-pipeline/dist.html#measure=WEBRTC_DTLS_CIPHER <https://telemetry.mozilla.org/new-pipeline/dist.html#measure=WEBRTC_DTLS_CIPHER>

Bug tracking the deactivation:
https://bugzilla.mozilla.org/show_bug.cgi?id=1227519 <https://bugzilla.mozilla.org/show_bug.cgi?id=1227519>

Targeted release: Firefox 66

Best
Nils Ohlmeier

[Nicholas Alexander]

On Wed, Aug 29, 2018 at 3:56 PM, Nils Ohlmeier <nohl...@mozilla.com>
wrote:

> Summary:
>
> We are looking at removing the DHE cipher suites from the DTLS handshake
> in Firefox soon.
>
> Ciphers:
> - TLS_DHE_RSA_WITH_AES_128_CBC_SHA
> - TLS_DHE_RSA_WITH_AES_256_CBC_SHA
> are the two suites which we want to remove, because they are considered
> too weak.
>

Are these suites considered "too weak" across the board? For historical
reasons Firefox for Android will handshake to Firefox Sync servers using
these suites:
https://searchfox.org/mozilla-central/rev/05d91d3e02a0780f44599371005591d7988e2809/mobile/android/services/src/main/java/org/mozilla/gecko/background/common/GlobalConstants.java#73.
Sounds like we should drop those suites there too -- can you confirm?

Nick

[Nicholas Alexander]

On Thu, Aug 30, 2018 at 2:15 PM, Nicholas Alexander <nalex...@mozilla.com>
wrote:

After a little (off-list) discussion, I've filed
https://bugzilla.mozilla.org/show_bug.cgi?id=1487842 tracking dropping
these.

Thanks, Nils (and others)!
Nick