Right but that's why I'm asking why not just put the limit on code_challange rather than inferring it from code_verifyer + challenge algorithm, which probably bounds it but doesn't necessarily do so? It's not a big deal but would read more clearly, I think.
On Mon, May 12, 2014 at 3:48 PM, John Bradley <ve7...@ve7jtb.com> wrote: > I think octets is more consistent with other JW* and OAuth specs. > > The code_challange is the same length as the code_verifyer or is a hash of > the code_verifyer so likely smaller than 128octets (43 ish for base64 256 > bit) > > Limiting the code_verifyer size sets the upper bound for code_challange, > unless someone comes up with a really creative code challenge algorithm. > > I will talk to nat about changing it to octets when I see him tomorrow. > > John B. > > On May 12, 2014, at 11:15 PM, Derek Atkins <warl...@mit.edu> wrote: > > > Brian Campbell <bcampb...@pingidentity.com> writes: > > > >> I notice that code_verifier is defined as "high entropy cryptographic > random > >> string of length less than 128 bytes" [1], which brought a few > questions and > >> comments to mind. So here goes: > >> > >> Talking about the length of a string in terms of bytes is always > potentially > >> confusing. Maybe characters would be an easier unit for people like me > to wrap > >> their little brains around? > > > > It depends if it really is characters or bytes. For example there are > > many multi-byte UTF-8 characters, so if it really is bytes then saying > > characters is wrong because it could overflow. So let's make sure we > > know what we're talking about. Historically, if we're talking bytes the > > IETF often uses the phrase "octets". Would that be less confusing? > > > >> Why are we putting a length restriction on the code_verifier anyway? It > seems > >> like it'd be more appropriate to restrict the length of the > code_challenge > >> because that's the thing the AS will have to maintain somehow (store in > a DB > >> or memory or encrypt into the code). Am I missing something here? > >> > >> Let me also say that I hadn't looked at this document since its early > days in > >> draft -00 or -01 last summer but I like the changes and how it's been > kept > >> pretty simple for the common use-case while still allowing for crypto > agility/ > >> extension. Nice work! > >> > >> [1] http://tools.ietf.org/html/draft-sakimura-oauth-tcse-03#section-3.3 > > > > -derek > > > >> _______________________________________________ > >> OAuth mailing list > >> OAuth@ietf.org > >> https://www.ietf.org/mailman/listinfo/oauth > > > > -- > > Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory > > Member, MIT Student Information Processing Board (SIPB) > > URL: http://web.mit.edu/warlord/ PP-ASEL-IA N1NWH > > warl...@mit.edu PGP key available > > -- [image: Ping Identity logo] <https://www.pingidentity.com/> Brian Campbell Portfolio Architect @ bcampb...@pingidentity.com [image: phone] +1 720.317.2061 Connect with us… [image: twitter logo] <https://twitter.com/pingidentity> [image: youtube logo] <https://www.youtube.com/user/PingIdentityTV> [image: LinkedIn logo] <https://www.linkedin.com/company/21870> [image: Facebook logo] <https://www.facebook.com/pingidentitypage> [image: Google+ logo]<https://plus.google.com/u/0/114266977739397708540> [image: slideshare logo] <http://www.slideshare.net/PingIdentity> [image: flipboard logo] <http://flip.it/vjBF7> [image: rss feed icon]<https://www.pingidentity.com/blogs/> [image: Register for Cloud Identity Summit 2014 | Modern Identity Revolution | 19–23 July, 2014 | Monterey, CA]<https://www.cloudidentitysummit.com/>
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