Establish a protected connection
03QUIC integrates a cryptographic handshake and transport-parameter negotiation. The cryptographic details are in RFC 9001.
Related RFCs and changes
“Updates” changes part of an earlier RFC. “Obsoletes” replaces it. This list shows selected related documents.
DIAGRAM§ 7 ↗
RFC 9000 · § 7EXAMPLE
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03
Protect established-connection traffic.
The connection can now carry application streams under application-data keys.
Protocol participantThreat or exceptionProtocol controlSimplified drawings · precise section references
RFC 9000 · QUIC version 1RFC 9369 § 3.2 · version 2
Version 2 changes long-header type encodings: Initial=01, 0-RTT=10, Handshake=11, Retry=00. These are wire-version differences, not RFC revision numbers.
Read the updated RFC section ↗Handshake progress establishes keys and transport context.
- Initial, Handshake, and 1-RTT packets have different protection contexts.
- Initial protection does not provide secrecy from an observer who can derive the public Initial keys.
- Before address validation, a server limits bytes sent to an address to three times bytes received from it.
0-RTT can reduce startup latency on resumed connections, but replay risks need application handling. Client Initial datagrams are padded to at least 1200 bytes.
Read the RFC section ↗Diagrams simplify the RFC. Read the linked sections for complete requirements.
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