[core] Roman Danyliw's No Objection on draft-ietf-core-echo-request-tag-12: (with COMMENT)

[Roman Danyliw via Datatracker <[e-mail]>]

Roman Danyliw has entered the following ballot position for
draft-ietf-core-echo-request-tag-12: No Objection

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COMMENT:
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Thank you for writing this mitigation for draft-mattsson-core-coap-actuators.

** Section 5.  Per “As each pseudorandom number most only be used once …”, how
will that be possible when echo values as small are 1-byte are possible?

** Section 5.
However, this may not be an issue if the
   communication is integrity protected against third parties and the
   client is trusted not misusing this capability.

-- Why is the use of integrity presented as only a possibility here?  Didn’t
Section 2.3 require it when assuring the freshness requirement – “When used to
serve freshness requirements including client aliveness and state
synchronizing), the Echo option value MUST be integrity protected between the
intended endpoints ...”

-- Would it be clearer here to say that this is mitigation against an on-path
attacker, not against rogue/compromised clients?

** Appendix A helpfully tries to lay out recommendations.  A few comments:

-- all of the recommendations here have option values much larger than the
permitted minimum of 1-byte.  In addition to the recommendations, could the
circumstances of the lower bound also be discussed

-- it would be helpful to explicitly state which methods apply to the specific
use cases (client aliveness, request freshness, state synchronization, network 
address reachability).  For example, method 3 (persistent counter) notes that
it can be used for state synchronization but not client aliveness