Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

ServerHello "legacy_session_id_echo" field #298

Open
wants to merge 4 commits into
base: master
Choose a base branch
from
Open

ServerHello "legacy_session_id_echo" field #298

Changes from 2 commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
fa55c01
ServerHello "legacy_session_id_echo" field
hannestschofenig Mar 3, 2025
e41a49f
Update draft-ietf-tls-rfc9147bis.md
hannestschofenig Mar 3, 2025
62e1ea8
Update draft-ietf-tls-rfc9147bis.md
hannestschofenig Mar 3, 2025
e350b94
Update draft-ietf-tls-rfc9147bis.md
hannestschofenig Mar 3, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
15 changes: 11 additions & 4 deletions draft-ietf-tls-rfc9147bis.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -940,9 +940,16 @@ prevention mechanism for UDP-based protocols, unlike TCP-based protocols, for wh
TCP establishes return-routability as part of the connection establishment.

DTLS implementations do not use the TLS 1.3 "compatibility mode" described in
Appendix D.4 of {{!TLS13}}. DTLS servers MUST NOT echo the
"legacy_session_id" value from the client and endpoints MUST NOT send ChangeCipherSpec
messages.
Appendix D.4 of {{!TLS13}}. DTLS servers MUST NOT send ChangeCipherSpec messages
when negotiating DTLS 1.3.

Additionally, the "legacy_session_id_echo" field of the ServerHello
message, described in Section 4.1.3 of {{!TLS13}}, MUST be empty in DTLS
1.3. DTLS 1.3 servers MUST NOT echo the "legacy_session_id" value
from the ClientHello. DTLS 1.3 clients MUST abort the handshake with
an "illegal_parameter" alert if the field is not empty. This applies
even if the "legacy_session_id" field of the ClientHello is non-empty
due to a cached session set by a pre-DTLS 1.3 server.

With these exceptions, the DTLS message formats, flows, and logic are
the same as those of TLS 1.3.
Expand Down Expand Up @@ -1186,7 +1193,7 @@ dual-stack DTLS 1.2 / DTLS 1.3 client MUST, however, be prepared to
interact with a DTLS 1.2 server.


## ClientHello Message
## ClientHello Message {#ClientHelloMsg}

The format of the ClientHello used by a DTLS 1.3 client differs from the
TLS 1.3 ClientHello format, as shown below.
Expand Down