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<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US">Dear Greg,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US">Please find hereafter the summary of our discussion within the SDLS WG regarding the applicability of SDLS to USLP truncated transfer frame. Feel free to complement with
your own notes/remarks:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l1 level1 lfo3"><![if !supportLists]><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US"><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US">USLP truncated transfer frames are meant to be used for sending short commands (as short as 2 octets) to the spacecraft. Those short commands are typically hardware
commands (bypassing OBSW) or immediate commands (triggering on-board procedures/sequences). Those commands are not necessarily emergency commands. They can be used during normal operations also. They are critical commands. Therefore, it is desirable that they
can benefit from SDLS security protection;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l1 level1 lfo3"><![if !supportLists]><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US"><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US">SDLS minimum overhead (corresponding to TC baseline mode) is : Security Header (6 octets), Security Trailer – MAC (16 octets). This minimum overhead means that
SDLS protection as is , is only applicable to truncated frames fitting into 1 LDPC(256,512) codeblock (32 octet) : Frame header (5 octets), Sec Hdr (6 oct), MAC (16 oct), leaving 5 octet maximum for the command itself. If BCH is used on the link, using SDLS
would require several codeblocks per frame (at least 5). This can be acceptable, possibly even for emergency commands (e.g. tumbling spacecraft);<o:p></o:p></span></p>
<p class="MsoListParagraph"><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l1 level1 lfo3"><![if !supportLists]><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US"><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US">Reducing the overhead of SDLS would imply reducing the level of security provided by the protocol and taking into account additional constraints (number of key
invocations, number of forged attempts, …). For example, MAC could be truncated to 64-bit (minimum length with AES) and the Sec Hdr could be reduced to 4 octet (with a reduced anti-replay counter). Nevertheless, the WG concluded that it was not advisable to
design an SDLS “reduced overhead” baseline mode for this USLP truncated frame mode, because recommending a reduced security mode for critical commands is not appropriate for a standard.<o:p></o:p></span></p>
<p class="MsoListParagraph"><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l1 level1 lfo3"><![if !supportLists]><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US"><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US">Clear mode implementation is always an option for a given mission, although not recommended security-wise, whenever operational safety or link constraints requires
it.<o:p></o:p></span></p>
<p class="MsoListParagraph"><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US">Best regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US">Gilles<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#1F497D">Gilles MOURY</span><span style="font-size:12.0pt;font-family:"Times New Roman",serif;color:#1F497D">
<br>
</span><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#1F497D">CNES Toulouse</span><span style="font-size:12.0pt;font-family:"Times New Roman",serif;color:#1F497D">
</span><span style="color:#1F497D;mso-fareast-language:EN-US"><o:p></o:p></span></p>
<div>
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<p class="MsoNormal"><b>De :</b> SLS-SLP <sls-slp-bounces@mailman.ccsds.org> <b>De la part de</b> Moury Gilles<br>
<b>Envoyé :</b> mardi 27 octobre 2020 12:13<br>
<b>À :</b> Kazz, Greg J (US 312B) <greg.j.kazz@jpl.nasa.gov><br>
<b>Cc :</b> sls-sea-dls@mailman.ccsds.org; sls-slp@mailman.ccsds.org<br>
<b>Objet :</b> Re: [Sls-slp] Does SDLS apply to USLP truncated transfer frame ?<o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="color:#1F497D;mso-fareast-language:EN-US">Dear Greg,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US">Sorry for not being able to join the SLP meeting yesterday but I had another meeting at the same time that lasted more than scheduled.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US">For the issue you raised concerning the applicability of SDLS to truncated USLP frames, I will add it to the discussion of the SDLS WG on Wednesday. My feeling is that,
also security would be needed on those emergency commands, the fact that minimum length for Security Header is something like 6 octets (TC baseline mode for SDLS) and minimum length for Security Trailer is something like 16 octets (TC baseline mode for SDLS)
would make it :<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo2"><![if !supportLists]><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US"><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US">impossible to fit a truncated USLP Transfer Frame into a 7 octets BCH codeblock (truncated USLP Transfer Frame header is 5 octets leaving only 2 octets for data
field)<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo2"><![if !supportLists]><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US"><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US">only possible to fit a truncated USLP Transfer Frame into a 32 octets LDPC codeblock (leaving only 27 octets for data field – 22 octets being taken by Security
and Trailer)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US">We will discuss it further with the SDLS WG. I do not know whether shorter Security Header and Trailer can be envisioned for those emergency commands carried in truncated
USLP Transfer Frames.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US">See you (virtually) this afternoon for the SLP webmeeting. I will provide input for the TM and AOS pink sheets regarding MCID/VCID validation in order to align TM/AOS with
TC/USLP regarding this validation.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US">Best regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US">Gilles
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#1F497D">Gilles MOURY</span><span lang="EN-US" style="font-size:12.0pt;font-family:"Times New Roman",serif;color:#1F497D">
<br>
</span><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#1F497D">CNES Toulouse</span><span lang="EN-US" style="font-size:12.0pt;font-family:"Times New Roman",serif;color:#1F497D">
</span><span lang="EN-US" style="color:#1F497D;mso-fareast-language:EN-US"><o:p></o:p></span></p>
<div>
<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span lang="EN-US">De :</span></b><span lang="EN-US"> Kazz, Greg J (US 312B) <<a href="mailto:greg.j.kazz@jpl.nasa.gov">greg.j.kazz@jpl.nasa.gov</a>>
<br>
<b>Envoyé :</b> lundi 26 octobre 2020 18:45<br>
<b>À :</b> Moury Gilles <<a href="mailto:Gilles.Moury@cnes.fr">Gilles.Moury@cne<span lang="FR">s.fr</span></a></span>>;
<a href="mailto:sls-sdls@mailman.ccsds.org">sls-sdls@mailman.ccsds.org</a><br>
<b>Cc :</b> Kazz, Greg J (US 312B) via SLS-SLP <<a href="mailto:sls-slp@mailman.ccsds.org">sls-slp@mailman.ccsds.org</a>><br>
<b>Objet :</b> Does SDLS apply to USLP truncated transfer frame ?<o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-US">Dear Gilles and SLDS WG,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">SLP WG has a question regarding the application of the SDLS protocol to truncated USLP Transfer Frames.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">These truncated frames are envisioned for very short length telecommands or forward link Proximity-1 link commanding. This frame type provides backward compatibility with TC hardware commands or immediate commands. These
commands are typically 2 octets long. We envision the truncated USLP frame length to be between 8 and 32 octets.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">In that context, does it make sense for SDLS header and possibly SDLS trailer to apply to the USLP truncated frame.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">The discussion of the proposed non-use of SDLS for truncated USLP frames is mentioned in Chapter 6, specifically in Section 6.3.2. The definition of the truncated USLP frame is in Annex G of the attached draft document<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">The SLP WG did not think SDLS should be applicable to truncated USLP frames, but we would like your opinion on this matter.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Best regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Greg Kazz<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Chair SLP WG<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span lang="EN-US" style="font-size:12.0pt;color:black">From:
</span></b><span lang="EN-US" style="font-size:12.0pt;color:black">SLS-SLP <<a href="mailto:sls-slp-bounces@mailman.ccsds.org">sls-slp-bounces@mailman.ccsds.org</a>> on behalf of Matthew Cosby <<a href="mailto:Matt.Cosby@Goonhilly.org">Matt.Cosby@Goonhilly.org</a>><br>
<b>Date: </b>Monday, October 26, 2020 at 9:27 AM<br>
<b>To: </b>"<a href="mailto:sls-slp@mailman.ccsds.org">sls-slp@mailman.ccsds.org</a>" <<a href="mailto:sls-slp@mailman.ccsds.org">sls-slp@mailman.ccsds.org</a>><br>
<b>Subject: </b>[EXTERNAL] [Sls-slp] Updated Book<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
</div>
<p class="MsoNormal"><span lang="EN-US">All,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Here is the updated book from the working group today.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Regards, Matt.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> <o:p></o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US" style="mso-fareast-language:EN-GB">Matthew Cosby</span></b><span lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US" style="mso-fareast-language:EN-GB">Chief Technology Officer
</span></b><span lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US" style="mso-fareast-language:EN-GB">Goonhilly Earth Station Ltd</span></b><span lang="EN-US"><o:p></o:p></span></p>
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