Yeah, I agree with John here. There are a few good reasons to restrict the length of the code_challenge. One is trying to keep the authorization request URI to reasonable size as it will eventually run into various limits on clients and/or servers. The other is constraining the amount of data that an AS needs to store per code.
On Fri, May 16, 2014 at 7:41 AM, John Bradley <ve7...@ve7jtb.com> wrote: > From the AS side you probably want to know what the max size you need to > store per code. > > On the call to the token endpoint it is a POST so size should not be an > issue. > > > On May 16, 2014, at 3:10 PM, Nat Sakimura <sakim...@gmail.com> wrote: > > Now that I cannot remember what limit we were hitting, it might be a good > idea to remove the constraint and see if anyone protests. > > What do you think? > > Nat > > > 2014-05-14 20:46 GMT+09:00 Brian Campbell <bcampb...@pingidentity.com>: > >> That too would suggest that the length limit be on code_challenge because >> that's the parameter that will be on URIs getting passed around. The >> code_verifier is sent directly in the POST body from client to AS. >> >> >> On Tue, May 13, 2014 at 12:52 AM, Nat Sakimura <sakim...@gmail.com>wrote: >> >>> +1 for octet. We used to have "bytes" in JW* so I used "bytes" here, >>> while at the same time complaining in Jose that it should be "octet". JW* >>> changed to "octet" but I failed to sync with it in the last few edits. >>> >>> I do not quite remember which platform, but the reason for the limit was >>> that some platform had some limitations as to the length of the sting to be >>> passed to it through URI and we did not want the challenges to be truncated >>> by that limit. >>> >>> Best, >>> >>> Nat >>> >>> >>> 2014-05-13 6:56 GMT+09:00 Brian Campbell <bcampb...@pingidentity.com>: >>> >>> And it'd give the AS some direct guidance on protecting itself from >>>> crazy long code_challenge values rather than relying on the client not to >>>> do something creative. >>>> >>>> >>>> On Mon, May 12, 2014 at 3:54 PM, Brian Campbell < >>>> bcampb...@pingidentity.com> wrote: >>>> >>>>> 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/> >>>>> >>>>> >>>> >>>> >>>> -- >>>> [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/> >>>> >>>> >>>> _______________________________________________ >>>> OAuth mailing list >>>> OAuth@ietf.org >>>> https://www.ietf.org/mailman/listinfo/oauth >>>> >>>> >>> >>> >>> -- >>> Nat Sakimura (=nat) >>> Chairman, OpenID Foundation >>> http://nat.sakimura.org/ >>> @_nat_en >>> >> >> >> >> -- >> [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/> >> >> > > > -- > Nat Sakimura (=nat) > Chairman, OpenID Foundation > http://nat.sakimura.org/ > @_nat_en > > >
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