Re: [DNSOP] Fwd: New Version Notification for draft-ietf-dnsop-algorithm-update-01.txt

Viktor Dukhovni <ietf-dane@dukhovni.org> Thu, 07 June 2018 06:39 UTC

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Subject: Re: [DNSOP] Fwd: New Version Notification for draft-ietf-dnsop-algorithm-update-01.txt
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On Tue, Jun 05, 2018 at 09:02:07PM +0200, Ondřej Surý wrote:

> Could I ask for more reviews, so we can progress this document forward?
> 

A couple of quick comments:

1.  Perhaps it might not be clear to all readers whether the
    table in Section 3.1 is *software* implementation advice or
    operational deployment advice?

    Seeing that Ed25519 is RECOMMENDED for signing makes me think that
    this software implementation advice, since signing zones with
    Ed25519 seems presently premature.

2.  I see that RSA-SHA512 (algorithm 10) is not recommended for
    signing, and indeed it is not very widely deployed.  Out of
    ~7.6 million signed domains I see ~72k with algorithm 10 ZSKs
    and KSKs, while algorithm 8 is used by ~3.6 million domains in
    KSKs and ZSKs (a ratio of 50:1 for alg 8 : alg 10).

    And yet, while it is not popular I don't see that any validators
    supporting RSA and SHA256 are at all likely not to support RSA
    and SHA512.  And furthermore, on 64-bit systems SHA512 tends
    to be somewhat faster (more with larger input sizes), because
    it processes input in 64-bit blocks.  On my x86_64 laptop,
    running OpenSSL 1.1.1 beta 'speed -evp', gives:

      type  16 bytes     64 bytes    256 bytes   1024 bytes   8192 bytes  16384 bytes
    sha256 39497.53k   114122.11k   266197.16k   395693.40k   461698.39k  469658.28k
    sha512 30863.64k   122424.60k   278926.37k   495961.09k   643754.67k  654338.73k

    So I am not sure that algorithm 10 warrants discouragement so
    long as 8 is required.  Everyone is going to have both, and
    they're basically the same...  While the case *for* 10 is not
    strong, the case against 10 looks somewhat weak (does supporting
    10 for signing carry a real cost?)

-- 
	Viktor.