Forwarded this conversation from the TLS list. The question is about changing the key derivation.
Joe ---------- Forwarded message --------- From: Joseph Salowey <[email protected]> Date: Tue, Jan 5, 2021 at 10:24 PM Subject: Re: [TLS] [Emu] Fwd: Benjamin Kaduk's Discuss on draft-ietf-emu-eap-tls13-13: (with DISCUSS and COMMENT) To: Alan DeKok <[email protected]> Cc: Mohit Sethi M <[email protected]>, EMU WG <[email protected]>, Benjamin Kaduk <[email protected]>, [email protected] <[email protected]> On Tue, Jan 5, 2021 at 8:31 AM Alan DeKok <[email protected]> wrote: > On Jan 5, 2021, at 11:13 AM, Mohit Sethi M <[email protected]> > 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. > > _______________________________________________ > TLS mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/tls >
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