Re: [openpgp] Wording/meaning (draft-06, 5.13.1)

[Justus Winter <[e-mail]>]

Bruce Walzer <[e-mail]> writes:

> At the end of section 5.13.1, at the end of the "NON-NORMATIVE
> EXPLANATION" is the following text:
>
>>However, no update will be needed because the MDC has been replaced
>>by the AEAD encryption described in this document.
>
> Which seems to refer to the previous text somehow but it is not clear
> how as there is no discussion of any sort of an update in the
> previous text.

The text with a little bit of context is:

  Note also that unlike nearly every other OpenPGP subsystem, there are
  no parameters in the MDC system. It hard-defines SHA-1 as its hash
  function. This is not an accident. It is an intentional choice to
  avoid downgrade and cross-grade attacks while making a simple, fast
  system. (A downgrade attack would be an attack that replaced SHA2-256
  with SHA-1, for example. A cross-grade attack would replace SHA-1 with
  another 160-bit hash, such as RIPEMD-160, for example.)

  However, no update will be needed because the MDC has been replaced by
  the AEAD encryption described in this document.

The text talking about not needing to update refers to the fact that the
MDC system is not parameterized.

Previously, in RFC4880, the paragraph you quoted read:

      However, given the present state of hash function cryptanalysis
      and cryptography, it may be desirable to upgrade the MDC system to
      a new hash function.  See Section 13.11 in the "IANA
      Considerations" for guidance.

Does that clear things up?  Maybe you can suggest some text to make this
clearer?

Best,
Justus