Subject: [lp-wan] Small point about calling it a "MIC"

From: Charlie Perkins <[email-masked]>
Date: Wed, 27 Mar 2019 07:21:34 -0700

Hello folks,

Yesterday I tried to describe some conversation about MIC versus FCS 
which happened during the recent IEEE 802.15 meeting.  The conclusion 
there, was that "MIC" isn't a good name for what SCHC specifies, because 
a MIC is considered to be something that offers a stronger guarantee of 
integrity than can be provided by the checksums recommended in the SCHC 
document.

I don't think FCS (i.e., "Frame Check Sequence") is exactly right 
either, because what is being checked is a reassembled packet, not a 
frame.  That is, if you think a frame is a layer-2 bitstring versus a 
packet being a layer-3 bitstring (I'm running out of words).

One possibility is to simply call it a checksum (abbreviated CHK?).

Regards,
Charlie P.

---

From: Carsten Bormann <[email-masked]>
Date: Wed, 27 Mar 2019 15:30:26 +0100

What are we protecting?

[_] Message [_] Frame [_] Packet [X] Datagram

What is it being used for? To…

[X] Check [_] Integrity check [as in security]

What is it?

[_] Sum [X] Sequence [x] Word [X] Bits [X] Value

What should we pick?

Grüße, Carsten

> On Mar 27, 2019, at 15:21, Charlie Perkins <[email-masked]> wrote:
> 
> Hello folks,
> 
> Yesterday I tried to describe some conversation about MIC versus FCS which happened during the recent IEEE 802.15 meeting.  The conclusion there, was that "MIC" isn't a good name for what SCHC specifies, because a MIC is considered to be something that offers a stronger guarantee of integrity than can be provided by the checksums recommended in the SCHC document.
> 
> I don't think FCS (i.e., "Frame Check Sequence") is exactly right either, because what is being checked is a reassembled packet, not a frame.  That is, if you think a frame is a layer-2 bitstring versus a packet being a layer-3 bitstring (I'm running out of words).
> 
> _______________________________________________
> lp-wan mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/lp-wan
> 
>

---

From: "Carles Gomez Montenegro" <[email-masked]>
Date: Thu, 28 Mar 2019 10:56:44 +0100

Hi,

Strictly speaking, our current "MIC" allows to validate the correctness of
a reassembled "SCHC Packet" (which is a term defined by the SCHC draft).

Perhaps we could talk in terms of a "SCHC Packet Check Sequence".

The acronym could be "SCS" or "SPCS", or even "PCS".

Thoughts?

Cheers,

Carles

---

From: <[email-masked]>
Date: Thu, 28 Mar 2019 10:27:23 +0000

I was leaning towards something similar to what Carles just suggested.
More specifically, in order to emphasise the fact the our "MIC" *only*
protects the Fragmentation/Reassembly process, I was thinking RCS
(Reassembly Check Sequence).
I believe it does not convey the wrong impression that an unfragmented
SCHC Packet is somehow covered by it.
I trust it looks close enough to FCS for IEEE to feel comfortable with it,
and it's easier to pronounce than SPCS.

Opinions?

Dominique

Le 28/03/19 10:56, « lp-wan on behalf of Carles Gomez Montenegro »
<[email-masked] on behalf of [email-masked]> a écrit :

>> What is it being used for? Toâ€¦
>>
>> GrÃ¼ÃŸe, Carsten

_________________________________________________________________________________________________________________________

Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc
pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce message par erreur, veuillez le signaler
a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques etant susceptibles d'alteration,
Orange decline toute responsabilite si ce message a ete altere, deforme ou falsifie. Merci.

This message and its attachments may contain confidential or privileged information that may be protected by law;
they should not be distributed, used or copied without authorisation.
If you have received this email in error, please notify the sender and delete this message and its attachments.
As emails may be altered, Orange is not liable for messages that have been modified, changed or falsified.
Thank you.

---

From: sivasothy shanmugalingam <[email-masked]>
Date: Thu, 28 Mar 2019 11:30:26 +0100

> a reassembled "SCHC Packet" (which is a term defined by the SCHC draft).

Correct.

> Perhaps we could talk in terms of a "SCHC Packet Check Sequence".

SCHC draft considers  "

Data unit out-of-sequence delivery does not occur between the
      entity performing fragmentation and the entity performing
      reassembly

"
SCHC fragment number is managed by Ack-always and Ack-on-Error. MIC can be
used to detect packet corrupt.
In No-Ack, that is not the case. In this case, MIC can be used to see
whether there is a fragment missing or not. It means some are missing.

so my proposal is "SCHC Packet Correctness Code".
Any thoughts?

Best regards
Sothy

---

From: Carsten Bormann <[email-masked]>
Date: Thu, 28 Mar 2019 12:11:23 +0100

On Mar 28, 2019, at 11:27, <[email-masked]> <[email-masked]> wrote:
> RCS

This.

Grüße, Carsten

---

From: Charlie Perkins <[email-masked]>
Date: Thu, 28 Mar 2019 04:35:42 -0700

+1

Regards,
Charlie P.

---

From: "Pascal Thubert (pthubert)" <[email-masked]>
Date: Thu, 28 Mar 2019 11:47:45 +0000

+1

All the best,

Pascal

> -----Original Message-----
> From: lp-wan <[email-masked]> On Behalf Of Charlie Perkins
> Sent: jeudi 28 mars 2019 12:36
> To: Carsten Bormann <[email-masked]>; [email-masked]
> Cc: lp-wan <[email-masked]>; Carles Gomez Montenegro
> <[email-masked]>
> Subject: Re: [lp-wan] Small point about calling it a "MIC"
> 
> +1
> 
> Regards,
> Charlie P.
>

---

From: "Carles Gomez Montenegro" <[email-masked]>
Date: Thu, 28 Mar 2019 13:28:08 +0100

+1 as well!

Carles

---

From: Alexander Pelov <[email-masked]>
Date: Thu, 28 Mar 2019 14:12:24 +0100

+1

Alexander

---

From: ana minaburo <[email-masked]>
Date: Thu, 28 Mar 2019 14:52:46 +0100

+1 for RCS

Ana

On Thu 28 Mar 2019 at 11:27, <[email-masked]> wrote:

> Ce message et ses pieces jointes peuvent contenir des informations
> confidentielles ou privilegiees et ne doivent donc
> pas etre diffuses, exploites ou copies sans autorisation. Si vous avez
> recu ce message par erreur, veuillez le signaler
> a l'expediteur et le detruire ainsi que les pieces jointes. Les messages
> electroniques etant susceptibles d'alteration,
> This message and its attachments may contain confidential or privileged
> information that may be protected by law;

---

From: Laurent Toutain <[email-masked]>
Date: Thu, 28 Mar 2019 14:59:24 +0100

+1

---

From: Juan Carlos Zuniga <[email-masked]>
Date: Thu, 28 Mar 2019 14:38:42 +0000

+1

From: lp-wan <[email-masked]> On Behalf Of Laurent Toutain
Sent: March 28, 2019 2:59 PM
To: ana minaburo <[email-masked]>
Cc: Charlie Perkins <[email-masked]>; lp-wan <[email-masked]>; Carsten Bormann <[email-masked]>; [email-masked]; BARTHEL Dominique IMT/OLPS <[email-masked]>
Subject: Re: [lp-wan] Small point about calling it a "MIC"

+1

On Thu, Mar 28, 2019 at 2:54 PM ana minaburo <[email-masked]<mailto:[email-masked]>> wrote:
+1 for RCS

Ana

On Thu 28 Mar 2019 at 11:27, <[email-masked]<mailto:[email-masked]>> wrote:

Opinions?

Dominique

Le 28/03/19 10:56, « lp-wan on behalf of Carles Gomez Montenegro »
<[email-masked]<mailto:[email-masked]> on behalf of [email-masked]<mailto:[email-masked]>> a écrit :

>>> On Mar 27, 2019, at 15:21, Charlie Perkins
>>> <[email-masked]<mailto:[email-masked]>> wrote:
>>>
>>> Hello folks,
>>>
>>> [email-masked]<mailto:[email-masked]>
>> [email-masked]<mailto:[email-masked]>
>[email-masked]<mailto:[email-masked]>

_______________________________________________
lp-wan mailing list
[email-masked]<mailto:[email-masked]>
https://www.ietf.org/mailman/listinfo/lp-wan
_______________________________________________
lp-wan mailing list
[email-masked]<mailto:[email-masked]>
https://www.ietf.org/mailman/listinfo/lp-wan