[Emu] Re: AD review draft-ietf-emu-eap-edhoc-06

[John Mattsson <[e-mail]>]

Hi Paul,

Thanks for the review.

>How does one determine the length of the EDHOC Message Length field?

This is described in the L field.


   L:  The L flag bits represent the binary encoding of the size of the
      EDHOC Message Length, which can range from 0 to 4 bytes.  When all
      three bits are set to 0, the EDHOC Message Length field is not
      present.  If the first two bits of the L field are set to 0 and
      the last bit is set to 1, then the size of the EDHOC Message
      Length field is 1 byte, and so on.  Values from 5 to 7 are not
      used in this specification.


Based on your question we should probably dd a sentence about this in the description of the “EDHOC Message Length” field. For example:


The EDHOC Message Length field, when present, has a size of one to four octets, as determined by the L flag bits. It is included only when the L flag bits indicate a value greater than zero and specifies the total length of the EDHOC message being fragmented. When fragmentation is not used, this field is omitted.



>I think RFC4137, RFC5216, RFC6677 should probably be normative references ?

I think making 4137 and 6677 normative make sense. I think RFC5216 should stay informative, the EAP-EDHOC packet format is just inspired by the EAP-TLS packet format.

Cheers,
John




From: Paul Wouters <[e-mail]>
Date: Tuesday, 27 January 2026 at 23:30
To: [e-mail] <[e-mail]>
Cc: [e-mail] <[e-mail]>
Subject: AD review draft-ietf-emu-eap-edhoc-06

AD review draft-ietf-emu-eap-edhoc-06

The draft looks generally fine and clear. I have one question and
one comment


 0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|     Code      |   Identifier  |            Length             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|     Type      |  R  |S|M|  L  |      EDHOC Message Length     ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                          EDHOC Data                           ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 7: EAP-EDHOC Request and Response Packet Format
4.1. EAP-EDHOC Request Packet



    The EDHOC Message Length field can have a size of one to four octets
    and is present only if the L flag bits represent a value greater than
    0. This field provides the total length of the EDHOC message that is
    being fragmented. When there is no fragmentation, it is not present.

EDHOC Data:

    The EDHOC data consists of the whole or a fragment of the transported EDHOC message.

How does one determine the length of the EDHOC Message Length field?



I think RFC4137, RFC5216, RFC6677 should probably be normative references ?

Paul