Re: [quicwg/base-drafts] Separate key/secret availability from usage (#1654)

[Christian Huitema <[e-mail]>]

huitema commented on this pull request.



> -CRYPTO frame in Handshake encryption) may send STREAM data (in 1-RTT
-encryption). However, if the Finished is lost, the client would have to
-retransmit the Finished, in which case it would use Handshake encryption.
-
+Although TLS only uses one encryption level at a time, QUIC may use more than
+one level. For instance, after sending its Finished message (using a CRYPTO
+frame at the Handshake encryption level) an endpoint can send STREAM data (in
+1-RTT encryption). If the Finished message is lost, the endpoint uses the
+Handshake encryption level to retransmit the lost message.
+
+In particular, server implementations need to be able to read packets at the
+Handshake encryption level before the final TLS handshake message at the 0-RTT
+encryption level (EndOfEarlyData) is available.  Though the content of CRYPTO
+frames at the Handshake encryption level cannot be forwarded to TLS before
+EndOfEarlyData is processed, the client could send ACK frames that the server
+needs to process in order to detect lost Handshake packets.
 

There is no requirement that QUIC guarantees ordering. In fact, it will deliver data from different streams in different order than they were received -- this is essential to avoid head of line blocking. The only guaranteed ordering is within a stream, or within a crypto stream.

Your paragraph develops the need for QUIC to handle the different Crypto contexts in parallel. That's fine, but in my mind that's not the same requirement as delivery of crypto-stream in specified order. In fact, just ordering them is not sufficient, because the QUIC implementation does not actually know how long a particular crypto stream is. There is no end mark. So how does it logically deduce that level N is now done, and that it is OK to proceed with N+1?

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