Re: [Emu] [TLS] Fwd: Benjamin Kaduk's Discuss on draft-ietf-emu-eap-tls13-13: (with DISCUSS and COMMENT)

[Joseph Salowey <[e-mail]>]

On Tue, Jan 5, 2021 at 8:31 AM Alan DeKok <[e-mail]> wrote:

> On Jan 5, 2021, at 11:13 AM, Mohit Sethi M <[e-mail]>
> wrote:
> >
> > Hi Alan,
> >
> > Cleaning up the email. The current draft says the exporter should be
> called once as:
> >
> >>    Key_Material = TLS-Exporter("EXPORTER_EAP_TLS_Key_Material",
> >>                                Type-Code, 128)
> >>
> > and then split the 128 into MSK (64) and EMSK (64). As said, from
> initial glance, it seems the exporter is called twice (once in
> eap_tls_get_emsk and once in eap_tls_getKey). Both the calls are with
> exactly the same context, context length, and labels. In getKey, the EMSK
> parts are cleared with
> >> os_memset(eapKeyData + EAP_TLS_KEY_LEN, 0, EAP_EMSK_LEN);
> > while in get_emsk, they are read with
> >
> >
> >>              os_memcpy(emsk, eapKeyData + EAP_TLS_KEY_LEN,
> >>
> >>
> >> EAP_EMSK_LEN);
> > Maybe we can live with this. But if exporter is called twice, we should
> use different labels as suggested by Martin?
>
>   Yes.
>
>   Perhaps as Joe suggested: EXPORTER_EAP_TLS_MSK and
> EXPORTER_EAP_TLS_EMSK, which seem simple enough.
>
> [Joe] I created a pull request (
https://github.com/emu-wg/draft-ietf-emu-eap-tls13/pull/17)  with the
proposed labels.  Is this change going to cause significant problems for
implementation?


>   Alan DeKok.
>
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