Michael: These words were first used by IPsec; see RFC 4307. They have gained broader acceptance. I see no problem just using them here.
Russ > On Jun 6, 2018, at 7:32 PM, Michael Richardson <mcr+i...@sandelman.ca> wrote: > > > In draft-ietf-ace-coap-est, we would like to specify some mandatory to > implement algorithms for DTLS. > > We write: > The mandatory cipher suite for DTLS in EST-coaps is > TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8 defined in [RFC7251] which is the > mandatory-to-implement cipher suite in CoAP. > > Additionally, the curve secp256r1 MUST be supported [RFC4492]; this curve > is equivalent to the NIST P-256 curve. > > And this is fine for now, but we'd like to signal that Curve25519 should be > considered as an alternative, but we don't want to make it a MUST *today*, > and we don't want to force implementations 15 years down the road that have > it to include secp256r1. > > IPsec(ME) has published things like: https://datatracker.ietf.org/doc/rfc8247/ > which include language like: > > SHOULD+ This term means the same as SHOULD. However, it is likely > that an algorithm marked as SHOULD+ will be promoted at > some future time to be a MUST. > > SHOULD- This term means the same as SHOULD. However, an algorithm > marked as SHOULD- may be deprecated to a MAY in a future > version of this document. > > MUST- This term means the same as MUST. However, it is expected > at some point that this algorithm will no longer be a MUST > in a future document. Although its status will be > determined at a later time, it is reasonable to expect that > if a future revision of a document alters the status of a > MUST- algorithm, it will remain at least a SHOULD or a > SHOULD- level. > > I don't think TLS has done this... maybe TLS plans to. > We think that we'd like to use SHOULD+ for Curve25519 and MUST- for > secp256r1, but we aren't sure that the WG will like us to use so many > words as IPsec to say so. > > -- > ] Never tell me the odds! | ipv6 mesh networks [ > ] Michael Richardson, Sandelman Software Works | network architect [ > ] m...@sandelman.ca http://www.sandelman.ca/ | ruby on rails > [ > > > _______________________________________________ > Ace mailing list > Ace@ietf.org > https://www.ietf.org/mailman/listinfo/ace
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