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A comment on TurboTLS: TLS connection establishment with 1 less round trip. Parent comment

Re:TurboTLS: TLS connection establishment with 1 less round ... by r1ch on Tuesday February 14, 2023 @04:39PM (#34796451)
There's a couple of "previously connected" bits with QUIC:

- The very first connection to a site is usually HTTP/2, which requires an additional RTT compared to QUIC, as the browser doesn't yet know if the server supports QUIC. In the response, the server can advertise the presence of QUIC support with the Alt-Svc header. This support flag can also be present in a HTTPS DNS record for the domain but that isn't queried by all browsers yet. Future connections to the same server will default to QUIC once the browser is aware of support, saving an additional RTT.

- Once connected to a QUIC server, the encryption keys can be cached for future connections, allowing the client to send data with the initial connection request (so called 0-RTT). This is only safe for idempotent requests though as this part of the protocol could be replayed by an attacker.

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Re:TurboTLS: TLS connection establishment with 1 less round ... by kixelated on Tuesday February 14, 2023 @07:22PM (#34798271)
You're right that HTTP/3 requires Alt-Svc at the moment. QUIC itself doesn't require a pre-established connection (1-RTT), which is notable for non-HTTP/3 protocols and WebTransport.
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