[tcpm] Re: Feedback on draft-ietf-tcpm-tcp-ao-algs-00

[Tony Li <[e-mail]>]

I prefer having at least two.  

Tony


> On Apr 28, 2026, at 10:42 AM, Bonica Ron <ronald.bonica=[e-mail]> wrote:
> 
> Folks,
> 
> I would be happy to trim the draft down to 1 KDF (HMAC-SHA236) and one MAC (HMAC-SHA256-128).
> 
> Does the WG agree?
> 
>                                                          Ron
> From: Eric Biggers <ebiggers=[e-mail] <mailto:ebiggers=[e-mail]>>
> Sent: Tuesday, April 28, 2026 1:16 PM
> To: Bonica, Ron <ronald.bonica=[e-mail] <mailto:ronald.bonica=[e-mail]>>
> Cc: Eric Biggers <ebiggers=[e-mail] <mailto:ebiggers=[e-mail]>>; [e-mail] <mailto:[e-mail]> <[e-mail] <mailto:[e-mail]>>
> Subject: [tcpm] Re: Feedback on draft-ietf-tcpm-tcp-ao-algs-00
>  
> On Tue, Apr 28, 2026 at 03:23:59PM +0000, Bonica, Ron wrote:
> > Eric,
> > 
> > Thanks for the review. I suspect that we will trim the list of proposed algorithms. Version-00 of the draft was just a starting point.
> > 
> > You say:
> > 
> > "I suggest simplifying the proposal to just HMAC-SHA256 for now.  That's the only one that seems like an obvious choice.  Indeed, SHA-256 is the usual replacement for the outdated SHA-1."
> > 
> > Do you mean HMAC-SHA256-128? Or do you really mean HMAC-SHA256?
> > 
> > I propose HMAC-SHA256 in draft-bonica-tcpm-tcp-ao-long-algs<https://urldefense.com/v3/__https://datatracker.ietf.org/doc/draft-bonica-tcpm-tcp-ao-long-algs/__;!!NpxR!ibHEtcU57NxmKdu5whL8_6s1wUbjBsR7qPAFLrNdke5w3vsAIt5w7fVNN7MW3xVHj_Vg_ZvX7QCqOxUoVyyuWWCBmS3zv_3s$ >. But if we go there, we need to solve the problem identified in TCP Extended Options<https://urldefense.com/v3/__https://datatracker.ietf.org/doc/draft-bonica-tcpm-extended-options/__;!!NpxR!ibHEtcU57NxmKdu5whL8_6s1wUbjBsR7qPAFLrNdke5w3vsAIt5w7fVNN7MW3xVHj_Vg_ZvX7QCqOxUoVyyuWWCBmVcDn5IJ$ >.
> 
> By "HMAC-SHA256-128" you just mean HMAC-SHA256 with the output truncated
> to 128 bits, right?  I wasn't implying that you wouldn't need to do that
> truncation.  The TCP options header doesn't have enough space for the
> full output, after all.
> 
> Note that the full HMAC-SHA256 output still must be used in the KDF.
> 
> - Eric
> 
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