[Sls-sea-dls] Key Verification using CRC

Tue Apr 19 13:49:01 UTC 2016

Bruno's proposal is a good technical solution by itself, but I have concerns about introducing additional requirements into ground crypto systems for generation and storage of meta-keys.

The CRC may not itself be a critical security parameter in the FIPS 140 sense (I think it is not, but I defer to others' judgment in this), but generation of the CRC requires access to critical security parameters, both the Key ID and the actual key itself.  So CRC generation would have to be performed within a validated crypto system, even if it were permissible to transmit and store the CRC outside the crypto system.

If Bruno's proposal were adopted as-is, it appears unlikely to me that any generic, commercially-available crypto systems could satisfy the requirement.  For flight systems, this may not be an issue since flight implementations tend to be custom by their very nature.  On the other hand, ground systems that otherwise might be able to integrate commercially-available crypto systems would be forced into procuring custom implementations requiring e.g. FIPS 140 validation along with its additional time and expense.

Craig

From: sls-sea-dls-bounces at mailman.ccsds.org [mailto:sls-sea-dls-bounces at mailman.ccsds.org] On Behalf Of Moury Gilles
Sent: Tuesday, April 19, 2016 3:46 AM
To: Weiss, Howard <Howard.Weiss at parsons.com>; Saba Bruno <Bruno.Saba at cnes.fr>; Daniel.Fischer at esa.int; sls-sea-dls at mailman.ccsds.org
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> [mailto:sls-sea-dls-bounces at mailman.ccsds.org] De la part de Weiss, Howard
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Objet : RE: [Sls-sea-dls] Key Verification using CRC

I agree with Bruno.

Howie

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From: sls-sea-dls-bounces at mailman.ccsds.org<mailto: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<mailto:Daniel.Fischer at esa.int>; sls-sea-dls at mailman.ccsds.org<mailto: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
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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> [mailto:sls-sea-dls-bounces at mailman.ccsds.org] De la part de Daniel.Fischer at esa.int<mailto:Daniel.Fischer at esa.int>
Envoyé : dimanche 17 avril 2016 13:13
À : sls-sea-dls at mailman.ccsds.org<mailto: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
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