<span style=" font-size:10pt;font-family:sans-serif">Well,</span>
<br>
<br><span style=" font-size:10pt;font-family:sans-serif">I think the point
here is whether it is 'must' or 'MUST'.</span>
<br>
<br><span style=" font-size:10pt;font-family:sans-serif">Is there any intention
to keep some flexibility for IETF DTN here or not?</span>
<br>
<br><span style=" font-size:10pt;font-family:sans-serif">It's an important
point for (efficient) on-board implementations. CCSDS should be very clear
on CBOR serialisation. So, I see four options</span>
<br>
<br><span style=" font-size:10pt;font-family:sans-serif">1) IETF has a
MUST, CCSDS confirms this MUST</span>
<br><span style=" font-size:10pt;font-family:sans-serif">2) IETF has a
'must'--> CCSDS makes is a MUST</span>
<br><span style=" font-size:10pt;font-family:sans-serif">3) IETF has a
MUST --> CCSDS decides to implement a different serialisation (to guarantee
fixed block sizes independent from actual values)</span>
<br><span style=" font-size:10pt;font-family:sans-serif">4) IETF has a
'must'--> CCSDS decides to implement a different serialisation</span>
<br>
<br><span style=" font-size:10pt;font-family:sans-serif">Clearly, 3) needs
to avoided and I would hope that we do not need to go to 4) ( the initial
feedback is that deterministic CBOR is ok for on-board implementations,
TBC).</span>
<br><span style=" font-size:10pt;font-family:sans-serif">Ideally, we would
have 1) but in order to avoid 3) we might want to stay with 1)</span>
<br>
<br><span style=" font-size:10pt;font-family:sans-serif">On the indefinite-length
exception, I'm not sure. I think the requirement for deterministic CBOR
is on the blocks/fields and not the entire bundle (which is currently the
only indefinite length item).</span>
<br><span style=" font-size:10pt;font-family:sans-serif">So, we might allow
indefinite-length also in blocks (which may lead to slightly more efficient
encoding but might make decoding slightly more difficult). In this case,
we might want to extend the deterministic CBOR requirement (with the exception)
to the whole bundle.</span>
<br><span style=" font-size:10pt;font-family:sans-serif">Or we might not
allow in-definite length for blocks/fields and state explicitly that this
does not apply to the full bundle.</span>
<br>
<br><span style=" font-size:10pt;font-family:sans-serif">(I do hope, I
have not been to confusing. It's still quite early for me.)</span>
<br>
<br><span style=" font-size:10pt;font-family:sans-serif">Regards,</span>
<br><span style=" font-size:10pt;font-family:sans-serif">Felix</span>
<br>
<br>
<br>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">From:
</span><span style=" font-size:9pt;font-family:sans-serif">"Birrane,
Edward J." <Edward.Birrane@jhuapl.edu></span>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">To:
</span><span style=" font-size:9pt;font-family:sans-serif">"Dr.
Keith L Scott" <kscott@mitre.org>, "Scott Burleigh"
<scott.c.burleigh@jpl.nasa.gov></span>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Cc:
</span><span style=" font-size:9pt;font-family:sans-serif">"sis-dtn@mailman.ccsds.org"
<sis-dtn@mailman.ccsds.org></span>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Date:
</span><span style=" font-size:9pt;font-family:sans-serif">01/12/2021
21:30</span>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Subject:
</span><span style=" font-size:9pt;font-family:sans-serif">Re:
[Sis-dtn] [EXT] Canonical CBOR in BPv7 a MUST for block field encoding?</span>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Sent
by: </span><span style=" font-size:9pt;font-family:sans-serif">"SIS-DTN"
<sis-dtn-bounces@mailman.ccsds.org></span>
<br>
<hr noshade>
<br>
<br>
<br><span style=" font-size:12pt">I believe this is changed to deterministic
CBOR with the exception the indefinite length items are not prohibited.
</span>
<br>
<br><span style=" font-size:12pt">Sent with BlackBerry Work<br>
(</span><a href=www.blackberry.com><span style=" font-size:12pt">www.blackberry.com</span></a><span style=" font-size:12pt">)</span>
<br><span style=" font-size:12pt"><br>
</span>
<br><span style=" font-size:11pt"><b>From: </b>Dr. Keith L Scott <</span><a href=mailto:kscott@mitre.org><span style=" font-size:11pt;color:#0082bf"><u>kscott@mitre.org</u></span></a><span style=" font-size:11pt">></span>
<br><span style=" font-size:11pt"><b>Date: </b>Wednesday, Dec 01, 2021,
12:01 PM</span>
<br><span style=" font-size:11pt"><b>To: </b>Scott Burleigh <</span><a href=mailto:scott.c.burleigh@jpl.nasa.gov><span style=" font-size:11pt;color:#0082bf"><u>scott.c.burleigh@jpl.nasa.gov</u></span></a><span style=" font-size:11pt">>,
Birrane, Edward J. <</span><a href=mailto:Edward.Birrane@jhuapl.edu><span style=" font-size:11pt;color:#0082bf"><u>Edward.Birrane@jhuapl.edu</u></span></a><span style=" font-size:11pt">></span>
<br><span style=" font-size:11pt"><b>Cc: </b>sis-dtn@mailman.ccsds.org
<</span><a href="mailto:sis-dtn@mailman.ccsds.org"><span style=" font-size:11pt;color:#0082bf"><u>sis-dtn@mailman.ccsds.org</u></span></a><span style=" font-size:11pt">></span>
<br><span style=" font-size:11pt"><b>Subject: </b>[EXT] Canonical CBOR
in BPv7 a MUST for block field encoding?</span>
<br>
<table width=600 align=left style="border-collapse:collapse;">
<tr height=8>
<td width=600 bgcolor=#e0e0e0 style="border-style:none none none none;border-color:#000000;border-width:0px 0px 0px 0px;padding:0px 0px;"><span style=" font-size:12pt;color:red"><b>APL
external email warning: </b></span><span style=" font-size:12pt">Verify
sender kscott@mitre.org before clicking links or attachments</span></table>
<br><span style=" font-size:12pt"> </span>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">The
draft-31 spec says:</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri"> </span></p>
<br><span style=" font-size:10pt;font-family:Courier New">Cryptographic
verification of a block is possible only if the</span>
<br><span style=" font-size:10pt;font-family:Courier New"> sequence
of octets on which the verifying node computes its hash -</span>
<br><span style=" font-size:10pt;font-family:Courier New"> the
canonicalized representation of the block - is identical to the</span>
<br><span style=" font-size:10pt;font-family:Courier New"> sequence
of octets on which the hash declared for that block was</span>
<br><span style=" font-size:10pt;font-family:Courier New"> computed.
To ensure that blocks are always in canonical</span>
<br><span style=" font-size:10pt;font-family:Courier New"> representation
when they are transmitted and received, the CBOR</span>
<br><span style=" font-size:10pt;font-family:Courier New"> representations
of the values of all fields in all blocks </span><span style=" font-size:10pt;color:red;font-family:Courier New">must</span>
<br><span style=" font-size:10pt;font-family:Courier New"> conform
to the rules for Canonical CBOR as specified in [</span><a href=https://datatracker.ietf.org/doc/html/rfc8949><span style=" font-size:10pt;color:#0082bf;font-family:Courier New"><u>RFC8949</u></span></a><span style=" font-size:10pt;font-family:Courier New">].</span>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">Note
the non-capitalization of the MUST requirement. Was that intended
to be capitalized (and is it in the version that the RFC editor sent back)?
What are folks thoughts on capitalizing it as part of AUTH48?</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">
v/r,</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">
--keith</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri"> </span><tt><span style=" font-size:10pt">_______________________________________________<br>
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