[TLS] Next steps for Large Record Sizes for TLS and DTLS

[John Mattsson <[e-mail]>]

Hi,

My summary from the TLS WG session yesterday:

- Let’s adopt and figure out the final details later.
- Show performance data.
- Should be new extension, i.e., not used together with "record size limit".
- The new extension should redefine the meaning of the uint16 length field in the TLSCiphertext to allow records larger than 2^16 bytes.

Simple suggestion:

In the new extension the client and server negotiate an uint8 value n. Client suggest a value n_max. Server selects n where 0 <= n <= n_max or rejects the extension. Agreeing on a value n means:

- The length field in the record means 2^n * length bytes instead of length bytes. I.e., left shifted similar to the TCP window scale option.
- The client and server are willing to receive records of size 2^n * (2^16 - 1) bytes.
- Up to 2^n - 1 bytes of padding might be required.
- AEAD limits are reduced with a factor 2^(n+2).

Thought?

Cheers,
John Preuß Mattsson

From: [e-mail] <[e-mail]>
Date: Tuesday, 5 March 2024 at 06:16
To: John Mattsson <[e-mail]>, Michael Tüxen <[e-mail]>, Hannes Tschofenig <[e-mail]>, Hannes Tschofenig <[e-mail]>, John Mattsson <[e-mail]>, Michael Tuexen <[e-mail]>
Subject: New Version Notification for draft-mattsson-tls-super-jumbo-record-limit-02.txt
A new version of Internet-Draft
draft-mattsson-tls-super-jumbo-record-limit-02.txt has been successfully
submitted by John Preuß Mattsson and posted to the
IETF repository.

Name:     draft-mattsson-tls-super-jumbo-record-limit
Revision: 02
Title:    Large Record Sizes for TLS and DTLS
Date:     2024-03-04
Group:    Individual Submission
Pages:    6
URL:      https://www.ietf.org/archive/id/draft-mattsson-tls-super-jumbo-record-limit-02.txt
Status:   https://datatracker.ietf.org/doc/draft-mattsson-tls-super-jumbo-record-limit/
HTML:     https://www.ietf.org/archive/id/draft-mattsson-tls-super-jumbo-record-limit-02.html
HTMLized: https://datatracker.ietf.org/doc/html/draft-mattsson-tls-super-jumbo-record-limit
Diff:     https://author-tools.ietf.org/iddiff?url2=draft-mattsson-tls-super-jumbo-record-limit-02

Abstract:

   RFC 8449 defines a record size limit extension for TLS and DTLS
   allowing endpoints to negotiate a record size limit smaller than the
   protocol-defined maximum record size, which is around 2^14 bytes.
   This document specifies a TLS flag extension to be used in
   combination with the record size limit extension allowing endpoints
   to use a record size limit larger than the protocol-defined maximum
   record size, but not more than about 2^16 bytes.



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