Re: [openpgp] Sec. Considerations MUST about S2K [was: Re: I-D Action: draft-ietf-openpgp-crypto-refresh-02.txt]

Peter Gutmann <pgut001@cs.auckland.ac.nz> Sun, 28 February 2021 03:46 UTC

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From: Peter Gutmann <pgut001@cs.auckland.ac.nz>
To: Daniel Kahn Gillmor <dkg@fifthhorseman.net>, "Neal H. Walfield" <neal@walfield.org>, Paul Wouters <paul@nohats.ca>
CC: "openpgp@ietf.org" <openpgp@ietf.org>
Thread-Topic: [openpgp] Sec. Considerations MUST about S2K [was: Re: I-D Action: draft-ietf-openpgp-crypto-refresh-02.txt]
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Date: Sun, 28 Feb 2021 03:46:06 +0000
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Archived-At: <https://mailarchive.ietf.org/arch/msg/openpgp/Jr0MBbuBsSBZeY17qa169tW8SJc>
Subject: Re: [openpgp] Sec. Considerations MUST about S2K [was: Re: I-D Action: draft-ietf-openpgp-crypto-refresh-02.txt]
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Daniel Kahn Gillmor <dkg@fifthhorseman.net> writes:

>I'm not sure about this at all.  For example, consider a system that knows
>that the string is high-entropy ("good key equivalent") -- should they be
>prohibited from using Simple or Salted S2K?  Is this MUST really an
>interoperability concern as §6 of RFC 2119 suggests?

Agreed, but it's a pretty simple fix:

  Where it's likely that a low-entropy secret is being employed, a compliant
  application SHOULD use [...]

Peter.