Re: [Curdle] Genart last call review of draft-ietf-curdle-rsa-sha2-10

Hello Russ,

thank you for the review. Comments:

> I think that a better title for this document would be:
> Use of RSA Keys with SHA-256 and SHA-512 in Secure Shell (SSH)

I can make this change, but I should note this is not universally agreed
on. In a previous specification, which became RFC 6668:

https://www.ietf.org/rfc/rfc6668.txt

... the original draft called for e.g. "hmac-sha256", but there were
immediate concerns about ambiguity which led to "hmac-sha2-256" and
"hmac-sha2-512" being specified.

> The current wording seems to include SHA-224 and SHA-384,
> and that is not the intent of the author.

True, but in this case as well, I point out RFC 6668, where we have the
title:

"SHA-2 Data Integrity Verification for the Secure Shell (SSH) Transport
Layer Protocol"

... even though the document only specifies "hmac-sha2-256" and
"hmac-sha2-512".

It appears to me that it may not be necessary for a document to specify use
of all versions of SHA-2, in order to be accurately described as specifying
the use of SHA-2 in a context.

> I did not propose changing the strings in case people have
> already implemented against this specification.  If no one
> has implemented yet, then I would change those too.

This intuition is correct. It has been widely implemented and is deployed
on, very possibly, millions of systems. One can launch an off-the-shelf
Amazon instance that has a long-term-support edition of Ubuntu with a
version of OpenSSH that implements this.

> Section 5.1 should be expanded to say that following the NIST
> advice on key sizes and SHA-1 outside the US Government is
> prudent.

I can do this.

As instructed, I await instructions from the document shepherd.

denis

On Fri, Sep 1, 2017 at 8:55 AM, Russ Housley <housley@vigilsec.com> wrote:

> Reviewer: Russ Housley
> Review result: Almost Ready
>
> I am the assigned Gen-ART reviewer for this draft. The General Area
> Review Team (Gen-ART) reviews all IETF documents being processed
> by the IESG for the IETF Chair. Please wait for direction from your
> document shepherd or AD before posting a new version of the draft.
>
> For more information, please see the FAQ at
> <http://wiki.tools.ietf.org/area/gen/trac/wiki/GenArtfaq>.
>
> Document: draft-ietf-curdle-rsa-sha2-10
> Reviewer: Russ Housley
> Review Date: 2017-09-01
> IETF LC End Date: 2017-09-11
> IESG Telechat date: unknown
>
> Summary: Almost Ready
>
> Major Concerns: None
>
>
> Minor Concerns:
>
> I think that a better title for this document would be:
>
>    Use of RSA Keys with SHA-256 and SHA-512 in Secure Shell (SSH)
>
> These are two of the hash function in the SHA2 family, and there is no
> ambiguity about them being part of the SHA3 family.  Similarly, I think
> that the Abstract and Section 1 should explicitly names these two hash
> functions.  The current wording seems to include SHA-224 and SHA-384,
> and that is not the intent of the author.
>
> In Section 3, I suggest:
>    s/using SHA-2 [SHS] as hash./using SHA-256 or SHA-512 [SHS] as hash./
>    s/the hash used is SHA-2 256./the hash used is SHA-256./
>    s/the hash used is SHA-2 512./the hash used is SHA-512./
>
> Note:  I did not propose changing the strings in case people have already
> implemented against this specification.  If no one has implemented yet,
> then I would change those too.
>
>
> Section 5.1 should be expanded to say that following the NIST advice on
> key sizes and SHA-1 outside the US Government is prudent.
>
>
> Nits: None
>
>
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