Re: [COSE] Robert Wilton's No Objection on draft-ietf-cose-hash-algs-04: (with COMMENT)

[Jim Schaad <[e-mail]>]

-----Original Message-----
From: Robert Wilton via Datatracker <[e-mail]> 
Sent: Tuesday, June 9, 2020 9:43 AM
To: The IESG <[e-mail]>
Cc: [e-mail]; [e-mail]; [e-mail]; Ivaylo Petrov <[e-mail]>; [e-mail]
Subject: Robert Wilton's No Objection on draft-ietf-cose-hash-algs-04: (with COMMENT)

Robert Wilton has entered the following ballot position for
draft-ietf-cose-hash-algs-04: No Objection

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COMMENT:
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Hi,

Thank you for this document, I found it easy to read and understand.  A few minor comments:

1.  Introduction

   Indirect signing of content is a paradigm where the content is not
   directly signed, but instead a hash of the content is computed and
   that hash value, along with the hash algorithm, is included in the
   content that will be signed.  Doing indirect signing allows for a
   signature to be validated without first downloading all of the
   content associated with the signature.  This capability can be of
   even greater importance in a constrained environment as not all of
   the content signed may be needed by the device.

Would it be better to write "along with an identifier for the hash algorithm"?
[JLS] Totally makes sense - done

1.  Introduction

   The use of hashes to identify objects is something that has been very
   common.  One of the primary things that has been identified by a hash
   function for secure message is a certificate.  Two examples of this
   can be found in [ESS] and the newly defined COSE equivalents in
   [I-D.ietf-cose-x509].

Perhaps drop "newly defined"?
[JLS] done

3.2.  SHA-2 Hash Algorithms

   *  *SHA-256* is probably the most common hash function used
      currently.  SHA-256 is an efficient hash algorithm for 32-bit
      hardware.

Is this intended to imply that SHA-256 is not an efficient hash algorithm when running on 64-bit hardware?  If so, that might be worth explicitly stating, although it is implied by the description for SHA-512/256.
[JLS] I don't think so, the algorithm is less efficient than SHA-512 on 64-bit hardware but without making the relative statement it is less useful.  I think that we are making statements about efficiency in the next line is sufficiently close.

3.3.  SHAKE Algorithms

Would this be more clear to be titled as SHA-3 Algorithms?
[JLS] No I don't think so.  The SHA-3 family defined SHA3-256 and SHAKE-256.  I think that using SHAKE in the title makes it clear we are not dealing with the first group of hash functions.

JIM


Thanks,
Rob