On 8/15/2014 1:48 PM, Pete Resnick wrote: > Hatless... > > On 8/15/14 3:26 PM, Dave Crocker wrote: >> On 8/15/2014 1:15 PM, Paul Wouters wrote: >> >> >>> The draft's definition of opportunism is "encrypt where possible, even >>> without authentication, but mandate authenticated encryption when >>> advertised". >>> >> It does not say the first part, though that language looks quite good >> to me. >> >> The second part isn't opportunisticx. If authenticated is mandated, >> there is nothing to be opportunistic about. If mandated is included in >> opportunistic, then there is no actual meaning to the term other than >> something trivial like "we like encryption". > > Disagree. Paul's definition still missed a bit, and I think it was the > word "mandate" that confused things. That's merely one of several examples that demonstrate the problem of conflating a portion of the scenario that allows no flexibility, which a portion that does. > Opportunism here is to take the opportunity to do the *best* encryption Right. Hence the phrase "best effort" makes sense. In any case, this entire topic is notably being pursued in response to the problem of having scenarios that are overly demanding, with either authenticated encryption or no encryption (or no session.) That is, the entire point behind this exercise is to specify scenarios that say "try to do authenticated encryption, but if you can't, then do unauthenticated." > you can do. If the other end advertises authenticated encryption, you > take the opportunity to do authenticated encryption. If that's > unavailable but you can do unauthenticated encryption, that's the best > you can do and you opportunistically do that. The difference from the > past is that you don't simply give up on encryption if you can't do > authenticated strong encryption; you opportunistically use whatever > encryption you are able to. Yup. You use encryption. Keep that point in mind. Opportunistic is about choices in encryption. It is not about 'no encryption'. It is not about "requiring only and exactly one kind of encryption'. >> My definition: >> >> Opportunism is the flexibility to use less-stringent protection, >> hen stronger protection is not possible. >> > > Using less-stringent protection when stronger protection is not > available is not an "opportunity". It's a compromise. Clever language play, but entirely the wrong focus. Worse, the idea that you could put forward such a different perspective on use the word opportunistic than I've been using -- that is, that we could have such a basic disconnect -- speaks, yet again, to the failure of this draft to be clear about its nature and its choices. The focus on "opportunity" is permitting fallback, rather than choosing cleartext of no session. Note the subtitle: Some Protection Most of the Time. > The opportunity is > to go *up* from what you currently do, not to go down from what you > might have done had circumstances been different. That's simply inaccurate, in terms of how this topic has been consistently discussed, and more especially in terms of what problem it is trying to fix. d/ -- Dave Crocker Brandenburg InternetWorking bbiw.net