commit 7276b974b78ea4f409d8738b1b6f1515f7a8968e
author Benjamin Wright <benwright@webrtc.org> Wed Mar 06 19:51:34 2019
committer Commit Bot <commit-bot@chromium.org> Wed Mar 06 20:44:41 2019
tree ca18775463ab3850bf2982cecb9e998fa3d25f33
parent 4423c36448f58fef925204871de940b4e8771ef6

Disable DTLS 1.0, TLS 1.0 and TLS 1.1 downgrade in WebRTC.

This change disables DTLS 1.0, TLS 1.0 and TLS 1.1 in WebRTC by default. This
is part of a larger effort at Google to remove old TLS protocols:
https://security.googleblog.com/2018/10/modernizing-transport-security.html

For the M74 timeline I have added a disabled by default field trial
WebRTC-LegacyTlsProtocols which can be enabled to support these cipher suites
as consumers move away from these legacy cipher protocols but it will be off
in Chrome.

This is compliant with the webrtc-security-arch specification which states:

   All Implementations MUST implement DTLS 1.2 with the
   TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 cipher suite and the P-256
   curve [FIPS186].  Earlier drafts of this specification required DTLS
   1.0 with the cipher suite TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA, and
   at the time of this writing some implementations do not support DTLS
   1.2; endpoints which support only DTLS 1.2 might encounter
   interoperability issues.  The DTLS-SRTP protection profile
   SRTP_AES128_CM_HMAC_SHA1_80 MUST be supported for SRTP.
   Implementations MUST favor cipher suites which support (Perfect
   Forward Secrecy) PFS over non-PFS cipher suites and SHOULD favor AEAD
   over non-AEAD cipher suites.

Bug: webrtc:10261
Change-Id: I847c567592911cc437f095376ad67585b4355fc0
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/125141
Commit-Queue: Benjamin Wright <benwright@webrtc.org>
Reviewed-by: David Benjamin <davidben@webrtc.org>
Reviewed-by: Qingsi Wang <qingsi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27006}