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 _______________________________________________ OAuth mailing list OAuth@ietf.org https://www.ietf.org/mailman/listinfo/oauth
