RTT estimation is used to correct for the propagation delay involved in transmitting a session ticket and later having it used for 0-RTT. This helps narrow the window we use for anti-replay. The way it is to set a value when the ServerHello is set, then use that as a reference point when sending NewSessionTicket. This only works when NewSessionTicket is sent at the end of the handshake. If SSL_SendSessionTicket is sent later, the RTT estimate is massively inflated. The fix is to finalize the calculation of the estimate during the handshake.
Bug 1656429 Comment 0 Edit History
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RTT estimation is used to correct for the propagation delay involved in transmitting a session ticket and later having it used for 0-RTT. This helps narrow the window we use for anti-replay. The way it currently works is that a value is set when the ServerHello is sent, then that is used as a reference point when sending NewSessionTicket. This only works when NewSessionTicket is sent at the end of the handshake. If SSL_SendSessionTicket is sent later, the RTT estimate is massively inflated. The fix is to finalize the calculation of the estimate during the handshake.