Subject: [Perc] Roman Danyliw's No Objection on draft-ietf-perc-dtls-tunnel-09: (with COMMENT)

From: Roman Danyliw via Datatracker <[email-masked]>
Date: Wed, 30 Jun 2021 13:11:17 -0700

Roman Danyliw has entered the following ballot position for
draft-ietf-perc-dtls-tunnel-09: No Objection

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COMMENT:
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Thank you to Shawn Emery for the SECDIR review, and to Russ Housley for the
security related feedback in the GENART review.

** Section 5.4.
   The Key Distributor MUST match the certificate fingerprint and
   "external_session_id" received from endpoint's "ClientHello" message
   with the values received from the SDP transmitted by the endpoint.

Consider adding a reference to RFC8122 to point to the guidance on the SDP
fingerprint attribute.

** On the topic of relying on the RFC8122 defined hashes, Section 5 allows for
the possibility of SHA-1 which is now past its prime.  The text there already
says “Implementations compliant with this specification MUST NOT use the MD2
and MD5 hash functions to calculate fingerprints or to verify received
fingerprints that have been calculated using them.”  Likewise, Section 5.1 also
notes the requirement of at least one of the hashes being SHA-256.  Consider
saying sometime along the lines of “Implementations using this tunneling
approach SHOULD NOT use SHA-1 hash functions to calculate or verify
fingerprints …”