2020-gfw-esni-blocking
Exposing and Circumventing China's Censorship of ESNI
Abstract
August 2020 documentation of the GFW's blocking of TLS Encrypted SNI
(ESNI) traffic, with details on how the blocking is implemented and
proposed circumvention approaches.
Team notes
Historical: the GFW began blocking ESNI in 2020, well before ECH
rollout in browsers. Lantern protocol designs that assume ECH gives
hostname privacy in CN need to start from this paper. ECH-based
defenses haven't been a major Lantern bet yet but anyone considering
it should know this is the prior art and the GFW already has
detector code.