[Sls-sea-dls] Key Verification using CRC

Tue Apr 19 09:24:00 UTC 2016

Dear all,

I checked as well with our internal expert who provided the suggestion to 
change the key verification in the first place

He is fine with the suggested change as well. Thus I would suggest we 
adopt it.

Cheers,
Daniel

Dr. Daniel Fischer
----------------------------
Data Systems Manager
Ground Segment Engineering Support Office (OPS-GE)
Ground Systems Engineering Department
Directorate of Operations

European Space Agency - ESOC
Robert-Bosch-Str. 5
D-64293 Darmstadt - Germany
Tel: +49 (0) 6151 90 2718 - Fax: +49 (0) 6151 90 2718
Web: http://www.esa.int

From:   "Moury Gilles" <Gilles.Moury at cnes.fr>
To:     "Weiss, Howard" <Howard.Weiss at parsons.com>, "Saba Bruno" 
<Bruno.Saba at cnes.fr>, "Daniel.Fischer at esa.int" <Daniel.Fischer at esa.int>, 
"sls-sea-dls at mailman.ccsds.org" <sls-sea-dls at mailman.ccsds.org>
Date:   19/04/2016 10:46
Subject:        RE: [Sls-sea-dls] Key Verification using CRC

Shall we adopt Bruno?s proposal ? In that case, we probably do not need 
the challenge-response transaction.

Gilles

Gilles MOURY 
CNES Toulouse 
De : sls-sea-dls-bounces at mailman.ccsds.org [
mailto:sls-sea-dls-bounces at mailman.ccsds.org] De la part de Weiss, Howard
Envoyé : lundi 18 avril 2016 19:27
À : Saba Bruno; Daniel.Fischer at esa.int; sls-sea-dls at mailman.ccsds.org
Objet : RE: [Sls-sea-dls] Key Verification using CRC

I agree with Bruno.

Howie

Howard Weiss
Technical Director

PARSONS
7110 Samuel Morse Drive
Columbia, MD 21046
443-430-8089 (office)
410-262-1479 (cell)
443-430-8238 (fax)
howard.weiss at parsons.com
www.parsons.com

Please consider the environment before printing this message

From: sls-sea-dls-bounces at mailman.ccsds.org 
[sls-sea-dls-bounces at mailman.ccsds.org] on behalf of Saba Bruno 
[Bruno.Saba at cnes.fr]
Sent: Monday, April 18, 2016 9:48 AM
To: Daniel.Fischer at esa.int; sls-sea-dls at mailman.ccsds.org
Subject: RE: [Sls-sea-dls] Key Verification using CRC
Dear all,

One solution to avoid the use of a challenge-response system and stay with 
the simple CRC for on-board key checking is to compute the CRC on BOTH the 
Key-ID and the key itself.

Ideally, what we know as a ?key? would be a ?Meta-Key?, comprising :

-          The Key ID, unique identifier of the key for the whole mission 
duration,
-          The Key itself (secret random data)
-          The CRC, computed on the Key ID and the key itself.

This ?Meta-Key? should be considered as an single entity, not splittable, 
being stored, transferred and distributed as is (on-board AND at ground 
level, from generation to destruction).

Cheers,

Bruno Saba 
CNES 
DCT/TV/IN 
18 Avenue Edouard Belin 
31401 TOULOUSE Cedex 9 
Tel : + 33 (0) 5 61 28 28 76 
Fax : + 33 (0) 5 61 28 19 96 

De : sls-sea-dls-bounces at mailman.ccsds.org [
mailto:sls-sea-dls-bounces at mailman.ccsds.org] De la part de 
Daniel.Fischer at esa.int
Envoyé : dimanche 17 avril 2016 13:13
À : sls-sea-dls at mailman.ccsds.org
Objet : [Sls-sea-dls] Key Verification using CRC

Dear all, 

I was discussing our new approach to key verification using the 
onboard-stored CRCs with David, 

He came up with a keen observation.   

The CRC-based key verification is somewhat weaker than one based on a 
challenge-response. The reason is that the CRC ensues you that the key at 
a certain slot is still OK in terms of integrity. In contrast to the 
challenge-response approach it DOES NOT tell you that the key is the same 
as the key with same key ID on ground. 

Is this an issue for us? What do you think? The only way we have to check 
key synchronisation is to use a key for actual traffic protection and see 
if it works. 

What do you think? 

Cheers 
Daniel 

Dr. Daniel Fischer
----------------------------
Data Systems Manager
Ground Segment Engineering Support Office (OPS-GE)
Ground Systems Engineering Department
Directorate of Operations

European Space Agency - ESOC
Robert-Bosch-Str. 5
D-64293 Darmstadt - Germany
Tel: +49 (0) 6151 90 2718 - Fax: +49 (0) 6151 90 2718
Web: http://www.esa.int[esa.int]
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