Re: [6lo] Éric Vyncke's Discuss on draft-ietf-6lo-ap-nd-13: (with DISCUSS and COMMENT)

["Pascal Thubert (pthubert)" <[e-mail]>]

Hello Eric : )

Many thanks for your review! I cc'ed SEC-DIR because we could really use their recommendation to solve some of your questions, more below.

Please see below:
 
> == DISCUSS ==
> 
> -- Section 4.4 --
> The length of the reserved field is not specified. Or am I missing something
> obvious ?

I concatenated the reserved fields in the picture and declared it as 40 bits. 
Also added the number of bits in the reserved fields of other structures.

> ----------------------------------------------------------------------
> COMMENT:
> ----------------------------------------------------------------------
> 
> == COMMENTS ==
> 
> -- Section 4.2 --
> While status is set to 0 when sending a NS, what is the expected behavior of a
> receiver ?

Changed to 
"
In NS messages it MUST be set to 0 by the sender and ignored by the receiver.
"
 
> -- Section 4.3 and 4.4 --
> Why is the Pad Length field a 8-bit field while the actual padding will always be
> less than 8 bytes. Suggest to make it a 3 or 4 bits field and extend the reserved
> field.

Actually I thought that if we want to extend the option in the future, it is better to indicate the length of the public key as follows:

   |     Type      |    Length     | Reserved|  Public Key Length  |

Where:

Public Key Length: 13-bit unsigned integer. The length of the Public Key field in bytes.
Public Key:  A variable-length field, size indicated in the Public Key Length field.
       	     JWK-Encoded Public Key [RFC7517]
>Padding:  A variable-length field completing the Public Key field to align to the next 8-bytes boundary.


Works?



> 
> -- Section 6.1 --
> About "Nonce option MUST contain a random Nonce value that was never used
> with this device", how can it be done? Keeping a local history? Giving some
> operational hints would bee welcome. Especially, when there are multiple 6LR in
> the LLN: how can they synchronize the nonce?

The nonce is used once, so there's no synchronization. A new pair is formed and exchanged at each validation.

The nonce game used here appear to be common practice. Yes, there's usually a need of local history, and the fact that we get a nonce from both side, apart from guaranteeing that the result is effectively unique to both parties, also makes the chances for history to repeat very low. 

CC'ing SEC-DIR: Please help: if there is a reference for that practice, what it takes to maintain a nonce, and why we have a nonce from both sides? Trying to reinvent that text does not look like a good idea for this draft.



> 
> -- References --
> Is there a reason why the crypto algorithms RFC 7748 and 8032 are not
> normative?

Interestingly they are informational. So that would be a downref. 

CC'ing SEC-DIR: Please help: should we make these refs normative? 


> 
> == NITS ==
> 
> -- Section 2.2 --
> To be honest, I am not a big fan of simply announcing concepts and referring to
> many other RFCs. Suggest to mention which terms and concepts are defined in
> each document. Else, the current section 2.2 mostly forces the readers to read
> all the references.

Yes and they are really there as additional reading, not normative.
I changed the text to 
" The reader may get additional context for this specification from the following references"
I also moved classical ND and SEND references to informational references.

Works?

> -- Section 6 --
> s/may use a same Crypto-ID/may use the same Crypto-ID/ ?

Done

Many thanks again Eric!

Let's see what SEC-DIR thinks

And a very happy new year (in France we have till Jan 31st to send wishes 😉)

Pascal