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Re: [Curdle] Martin Duke's No Objection on draft-ietf-curdle-ssh-kex-sha2-19: (with COMMENT)

Mark Baushke <mbaushke@gmail.com> Tue, 20 July 2021 02:59 UTC

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From: Mark Baushke <mbaushke@gmail.com>
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Date: Mon, 19 Jul 2021 19:59:23 -0700
Cc: draft-ietf-curdle-ssh-kex-sha2@ietf.org, curdle-chairs@ietf.org, curdle@ietf.org, Daniel Migault <mglt.ietf@gmail.com>
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To: Martin Duke <martin.h.duke@gmail.com>
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Subject: Re: [Curdle] Martin Duke's No Objection on draft-ietf-curdle-ssh-kex-sha2-19: (with COMMENT)
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Hi Martin,

> On Jul 19, 2021, at 7:36 AM, Martin Duke <martin.h.duke@gmail.com> wrote:
> 
> SHA2-256 is a reasonable hash for use in both the KDF and integrity check. It is reasonable for both gss and non-gss uses of curve25519 key exchange methods.

Ah. I think I understand your confusion. That said, it is not an integrity check, rather it is a way of ensuring that the session integrity is maintained across many different rekeying events. As such, something like this may be closer to what you want:

            SHA2-256 is a reasonable hash for use in both the KDF and
            session integrity. It is reasonable for both gss and
            non-gss uses of curve25519 key exchange methods.

A similar paragraph is provided for the SHA2-512 hash.

        Be safe, stay healthy
        -- Mark

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