Subject: [dtn] CRC: MAY/SHOULD/MUST and on what

From: "Marc Blanchet" <[email-masked]>
Date: Fri, 26 Jul 2019 12:51:26 -0400

Hello,
  from our AD review of BPBis, there was a question on whether a CRC 
MAY/SHOULD/MUST be implemented and on what (primary block, all blocks, 
payload). From the discussion in the room today, the draft currently 
says that if the source node is using BPSec, it does not have to use a 
CRC, since that integrity service is already done by BPsec. However, if 
the source node is not using BPsec, then it SHOULD/MUST do CRC. The 
question is whether the source node MUST ALWAYS provide a CRC (whether 
or not BPsec is used). If CRC is mandatory, then on which part of the 
bundle should it be applied? In the context of this discussion, recall 
that a primary block is immutable, while extension blocks are not.

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Does a CRC be always present in a) all Bundles, or b) only in bundles 
not using BPSec? (expected answer: a) or b))

If CRC is calculated, on which part of the Bundle: a) primary block, b) 
all blocks c) payload? (expected answer: a), b) or c))

Rationale for your answer?

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Regards, Marc.