[Sls-sea-dls] Question regarding the SDLS EP Standard

[David.Koisser at esa.int]

Dear SDLS WG members,

John and I have completed setting up the interoperability testing 
environment and now we are doing a few finishing touches. Whilst doing 
this a few questions arose regarding the SDLS EP standard:

1. In Section E4.2.2 (in the baseline mode description of Key Activation) 
and the following key procedures, it defines the Key ID fields to have a 
length of 16 bits. And then states:
"Values 0-65535 shall not be used to reference session keys."
Which would be all possible Key IDs and leave none for any session keys. 
Can you clarify?

2. While we are fairly sure it is implied: Does the M&C procedure Set ARC 
set the IV instead of the SN parameter in the regarding cases (e.g. 
AES-GCM)?

3. The standard is not addressing how to distinguish if a GVCID is 
regarding the TM or TC channels for the Start SA procedure. An example to 
clarify: 

A mission wants a different SA assigned on VC 0 for the uplink (e.g. 
authentication only) than the VC 0 for the downlink (e.g. authenticated 
encryption). To be able to set this with the Start SA procedure, it needs 
a way to distinguish between the TC and TM channel mapping to SPIs. As the 
GVCID is defined as:
GVCID = TFVN + SCID + VCID
And the 2 bits long TFVN may have the following values: 01 -> AOS; 10 -> 
Proximity-1; 00 -> TM- *or* TC-SDLP
The GVCID alone is not enough to distinguish between TC and TM and we are 
currently using a custom data structure for unambiguously identifying the 
channels in the Start SA procedure.

Best Regards,
David Koisser
This message and any attachments are intended for the use of the addressee or addressees only.
The unauthorised disclosure, use, dissemination or copying (either in whole or in part) of its
content is not permitted.
If you received this message in error, please notify the sender and delete it from your system.
Emails can be altered and their integrity cannot be guaranteed by the sender.

Please consider the environment before printing this email.


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.ccsds.org/pipermail/sls-sea-dls/attachments/20170301/617147dd/attachment.html>